Gestational Age-specific Mortality Research Articles

Neonatal mortality in singleton pregnancies: a 20-year retrospective study from a tertiary perinatal unit in Hong Kong.

The global neonatal death (NND) rate has been declining in recent decades, but there are no comprehensive data concerning the characteristics of NNDs in Hong Kong. This study investigated the trends and aetiologies of NNDs among singleton pregnancies in Hong Kong. This study included all cases of NND from singleton pregnancies in a tertiary hospital in Hong Kong between 2000 and 2019. The rates, clinical characteristics, and aetiologies of NND were compared between the first (2000-2009) and the second (2010-2019) decades. The NND rate decreased from 1.66/1000 livebirths (97 cases) in the first decade to 1.32/1000 livebirths (87 cases) in the second decade. Congenital or genetic abnormalities (82 cases) caused 44.6% of all NNDs. There was a significant reduction from 0.82/1000 livebirths in the first decade to 0.52/1000 livebirths in the second decade (P=0.037). Other causes of NND were prematurity (69 cases; 37.5%), sepsis (16 cases; 8.7%), hypoxic-ischaemic encephalopathy (15 cases; 8.2%), and sudden infant death syndrome (2 cases; 1.1%). Gestational age-specific neonatal mortality for moderately preterm neonates (31-33 weeks of gestation) significantly decreased from 34.73/1000 in 2000-2009 to 8.63/1000 in 2010-2019 (P=0.001), but there were no significant changes in neonatal mortality for other gestations. The NND rate in Hong Kong is among the lowest worldwide. Neonatal deaths in our centre declined over the past two decades, mainly because of improvements in the prenatal diagnosis and treatment of congenital or genetic abnormalities, as well as an improved survival rate among moderately preterm neonates.

Gestational age-specific neonatal mortality in Hong Kong: a population-based retrospective study.

The neonatal period is the most vulnerable period during childhood, with the risk of death being the highest even in developed countries/regions. Hong Kong's neonatal mortality (1‰) is among the world's lowest and has remained similar for 15years. This study aimed to explore neonatal deaths in Hong Kong in detail and determine whether neonatal mortality is reducible at such a low level. Live births in public hospitals in Hong Kong during 01 Jan 2006-31 Dec 2017 were included. Relevant data were extracted from the electronic medical records. Gestational age-specific mortality was calculated, and the trends were analyzed using the Cochran-Armitage trend test. Causes of death were summarized, and risk factors were identified in multivariate logistic regression analysis. In 490,034 live births, 755 cases (1.54‰) died during the neonatal period, and 293 (0.6‰) died during the post-neonatal period. The neonatal mortality remained similar overall (P = 0.17) and among infants born at 24-29weeks' gestation (P = 0.4), while it decreased in those born at 23 (P = 0.04), 30-36 (P < 0.001) and ≥ 37 (P < 0.001) weeks' gestation. Neonates born at < 27weeks' gestation accounted for a significantly increased proportion among cases who died (27.6%to 51.9%), with hemorrhagic conditions (24%) being the leading cause of death. Congenital anomalies were the leading cause of death in neonates born ≥ 27weeks' gestation (52%), but its cause-specific mortality decreased (P = 0.002, 0.6‰ to 0.41‰), with most of the decrease attributed to trisomy 13/18 and multiple anomalies. Reduction of neonatal mortality in developed regions may heavily rely on improved quality of perinatal and neonatal care among extremely preterm infants.

Changes in mortality rates among extremely preterm infants born before 25 weeks' gestation: Comparison between the 2005 and 2010 nationwide surveys in Japan

BackgroundThere is no consensus as to whether the outcomes of extremely preterm infants born <25 weeks' gestation have been constantly improving. AimsOur study aimed to clarify changes in mortality during hospitalization among extremely preterm infants. Study designComparison of mortality rates between the 2005 and 2010 retrospective nationwide surveys in Japan. SubjectsExtremely preterm infants born <25 weeks' gestation in Japan and registered in the nationwide surveys, 802 infants in 2005 and 797 in 2010, respectively. OutcomesMortality rates stratified by gestational age. Results and conclusionMortality rates <25 weeks' gestation decreased from 36.4% to 25.6% (difference − 10.8% [95% confidence interval {CI}: −15.3%, −6.2%]) in 2010 compared to 2005. Gestational age-specific mortality rates were lower in 2010 compared to 2005, except for 24 weeks' gestation: 66.0% vs. 50.0% (difference: −16% [95% CI: −29.8%, −21.2%]) and 45.7% vs. 25.5% (difference: −20.2%, [95% CI: −28.1, −12.3%]) at 22, and 23 weeks' gestation, respectively. After adjusting for explanatory variables, the probability of death during hospitalization in 2010 was significantly lower in infants born <25 weeks' gestation (adjusted odds ratio [aOR] 0.597 [95% CI: 0.471, 0.757], but when stratified by gestational age, it was only significant for infants born at 23 weeks' gestation (aOR 0.439 [95% CI: 0.303, 0.636]). In conclusion, the mortality rates among infants born <25 weeks' gestation have been steadily improving from 2005 to 2010 in Japan, but the practice for infants born at 22 weeks' gestation is still challenging.

What do the numbers say? - Introduction of the WHO ICD-PM classification and fetuses-at risk approach in perinatal audit, South India

Objective: In India, despite a reduction in perinatal mortality rate from 2014 to 2019, still birth rate is still the same at the national average of 4/1000 live births. As yet there is no nation-wide audit in India except for facility based audits. Hence the need for a simplified yet effective audit process exists. The aim of this study was to perform a qualitative perinatal audit and devise methods for future audits. Methods: We conducted a one year audit for all perinatal deaths using WHO ICD PM and 3-delay classification. Gestational age (GA) specific mortality was calculated for significant underlying factors using fetuses-at risk approach. Results: We recorded a perinatal mortality rate of 6.1/1000 births among booked cases and 21.32/1000 births among referred cases. Fetal growth restriction was the most common antenatal condition, accounting to 33.3% of antepartum deaths. Prematurity accounted to 52% of neonatal deaths. Phase 2 delay with delayed referrals in severe pre-eclampsia and Phase 1 delay with late visit (&gt; 24 h) to hospital after experiencing absent fetal movements were the most common identifiable delays. Hypertension stood out to be the single most common risk-factor. GA specific mortalities, calculated using fetuses-at risk approach, show a peak mortality rate at 30 weeks, 37 weeks and 38 weeks in pregnancies with early-onset preeclampsia, severe fetal growth restriction and medically treated gestational diabetes respectively. Conclusion: The audit identified significant contributing factors to the mortality. ICD-PM and 3-delay classification was simpler and easier to apply with wide areas of opportunities for secondary analysis.

Birthweight and gestational age-specific neonatal mortality rate in tertiary care facilities in Eastern Central Uganda.

BackgroundAn estimated 2.8 million neonatal deaths occur each year globally, which accounts for at least 45% of deaths in children aged less than 5 years. Birthweight and gestational age‐specific mortality estimates are limited in low‐resource countries like Uganda. A deeper analysis of mortality by birthweight and gestational age is critical in identifying the cause and potential solutions to decrease neonatal mortality.ObjectivesWe studied mortality before discharge in relation to birthweight and gestational age using a large sample size from selected tertiary care facilities in Uganda.MethodsWe used secondary data from the East Africa Preterm Birth Initiative study conducted in six tertiary care facilities. Birth records of infants born between October 2016 and March 2019 with a gestational age greater than or equal to 24 weeks and/or birthweight greater than or equal to 500 g were reviewed for inclusion in the analysis. Newborn death before discharge was the outcome variable of interest. Multivariable Poisson regression modeling was used to explore birthweight and gestational age‐specific mortality rate.ResultsWe analysed 50 278 birth records. Among these 95.3% (47 913) were live births and 4.8% (2365) were stillbirths. Of the 47 913 live births, 50% (24 147) were males. Overall, pre‐discharge mortality was 13.0 per 1000 live births. For each 1 kg increase in birthweight, mortality before discharge decreased by −0.016. As birthweight increases, the mortality before discharge decreased from 336 per 1000 live births among infants born between 500 and 999 g, to 4.7 per 1000 live births among infants born weighing 3500 to 3999 g, and increased again to 11.2 per 1000 live births among infants weighing more than 4500 g.ConclusionsOur study highlights the need for further research to understand newborn survival across different birthweight and gestational categories.

Gestational age-related neonatal survival at a tertiary health institution in Nigeria: The age of fetal viability dilemma

Background: Although the official age of fetal viability in Nigeria is 28 weeks, there are pockets of reports some anecdotal, of survival of babies delivered at younger gestational age (GA) from different parts of the country. The routine resuscitation and management of premature infants born before the official age of fetal viability (28 weeks) is likely to generate important ethical and medical concerns that are bound to influence our approach to the management of such infants.&#x0D; Aim: To determine the GAspecific neonatal mortality and survival among preterm deliveries at the National Hospital Abuja.&#x0D; Subjects and Methods: A retrospective review of relevant data from the National Hospital Neonatal Registry Database based on the Research Electronic Data Capture software (REDCap) was undertaken to determine the mortality rate of preterm babies managed in the neonatal intensive care unit (NICU) from January 2017 to February 2018. Disaggregated GA specific mortality rates were also computed to determine the fetal age at which extra uterine neonatal survival rate was at least 50%. Gestational age estimation was based on mothers’ last menstrual period (LMP) in over 96% of cases.Results: Sixty-three (63) of 305 preterm babies admitted died during hospitalization giving a mortality rate of 20.7%. This was significantly higher than the mortality rate among term babies (7.5%, P=0.01) hospitalized over the same period. Antenatal corticosteroid use was low (11.2%), 188 (25.8%) received CPAP for Respiratory Distress Syndrome (RDS), and none of the babies received surfactant or mechanical ventilation. There were no survivors among babies delivered at GA of 22-25 weeks (11, 3.6%). However, the survival rate at 26 weeks gestation was 53.8%, and this subsequently increased, reaching a peak of 96.5% survival at 35 weeks. RDS accounted for 53.9% of all deaths.&#x0D; Conclusion: It is concluded that the survival rate (53.8%) of babies at GA of 26 weeks despite minimal antenatal interventions and limited postnatal respiratory support was reasonably high, and this could serve the basis for discussions for a downward review of the age of fetal viability in Nigeria.&#x0D; Key words: Gestational age. Fetal viability

A new record linkage for assessing infant mortality rates in Ontario, Canada

ObjectiveInfant mortality statistics for Canada have routinely omitted Ontario—Canada’s most populous province—as a high proportion of Vital Statistics infant death registrations could not be linked with their corresponding Vital Statistics live birth registrations. We assessed the feasibility of linking an alternative source of live birth information with infant death registrations.MethodsAll infant deaths occurring before 365 days of age registered in Ontario’s Vital Statistics in 2010–2011 were linked with birth records in the Canadian Institute for Health Information’s hospitalization database. Crude birthweight-specific and gestational age-specific infant mortality rates were calculated, and rates examined according to maternal and infant characteristics.ResultsOf 1311 infant death registrations, only 47 (3.6%) could not be linked to a hospital birth record. The overall crude infant mortality rate was 4.7 deaths per 1000 live births (95% CI, 4.4 to 4.9), the same as previously reported for the rest of Canada in 2011. Infant mortality was higher in women < 20 years (5.8 per 1000 live births) and ≥ 40 years (5.9 per 1000 live births), and lowest among those aged 25–29 years (3.9 per 1000 live births). Infant mortality was notably higher in the lowest (5.1 per 1000 live births) residential income quintile than the highest (3.4 per 1000 live births).ConclusionUse of birth hospitalization records resulted in near-complete linkage of all Vital Statistics infant death registrations. This approach could enhance the conduct of representative surveillance and research on infant mortality when direct linkage of live birth and infant death registrations is not achievable.

Temporal trends in neonatal mortality and morbidity following spontaneous and clinician-initiated preterm birth in Washington State, USA: a population-based study

ObjectiveAfter a decade of increase, the preterm birth (PTB) rate has declined in the USA since 2006, with the largest decline at late preterm (34–36 weeks). We described concomitant changes...

Gestational age-specific perinatal mortality rates for assisted reproductive technology (ART) and other births.

Is perinatal mortality rate higher among births born following assisted reproductive technology (ART) compared to non-ART births? Overall perinatal mortality rates in ART births was higher compared to non-ART births, but gestational age-specific perinatal mortality rate of ART births was lower for very preterm and moderate to late preterm births. Births born following ART are reported to have higher risk of adverse perinatal outcomes compared to non-ART births. This population-based retrospective cohort study included 407 368 babies (391 952 non-ART and 15 416 ART)-393 491 singletons and 10 877 twins or high order multiples. All births (≥20 weeks of gestation and/or ≥400 g of birthweight) in five states and territories in Australia during the period 2007-2009 were included in the study, using National Perinatal Data Collection (NPDC). Primary outcome measures were rates of stillbirth, neonatal and perinatal deaths. Adjusted odds ratio (AOR) and 95% confidence interval (CI) were used to estimate the likelihood of perinatal death. Rates of multiple birth and low birthweight were significantly higher in ART group compared to the non-ART group (P < 0.01). Overall perinatal mortality rate was significantly higher for ART births (16.5 per 1000 births, 95% CI 14.5-18.6), compared to non-ART births (11.3 per 1000 births, 95% CI 11.0-11.6) (AOR 1.45, 95% CI 1.26-1.68). However, gestational age-specific perinatal mortality rate of ART births (including both singletons and multiples) was lower for very preterm (<32 weeks' gestation) and moderate to late preterm births (32-36 weeks' gestation) (AOR 0.61, 95% CI 0.53-0.70 and AOR 0.61, 95% CI 0.53-0.70, respectively) compared to non-ART births. Congenital abnormality and spontaneous preterm were the most common causes of neonatal deaths in both ART and non-ART group. Due to different cut-off limit for perinatal period in Australia, the results of this study should be interpreted with cautions for other countries. Australian definition of perinatal period commences at 20 completed weeks (140 days) of gestation and ends 27 completed days after birth which is different from the definition by World Health Organisation (commences at 22 completed weeks (154 days) of gestation and ends seven completed days after birth) and by Centers for Disease Control and Prevention (includes infant deaths under age 7 days and fetal deaths at 28 weeks of gestation or more). Preterm birth is the single most important contributing factor to increased risk of perinatal mortality among ART singletons compared to non-ART singletons. Further research on reducing early preterm delivery, with the aim of reducing the perinatal mortality among ART births is needed. Couples who access ART treatment should be fully informed regarding the risk of preterm birth and subsequent risk of perinatal death. There was no funding associated with this study. No conflict of interest was declared.

Explaining the recent decrease in US infant mortality rate, 2007–2013

The US infant mortality rate has been steadily decreasing in recent years as has the preterm birth rate; preterm birth is a major factor associated with death during the first year of life. The degree to which changes in gestational age-specific mortality and changes in the distribution of births by gestational age have contributed to the decrease in the infant mortality rate requires clarification. The objective of the study was to better understand the major contributors to the 2007-2013 infant mortality decline for the total population and for infants born to non-Hispanic black, non-Hispanic white, and Hispanic women. We identified births and infant deaths from 2007 and 2013 Centers for Disease Control and Prevention National Vital Statistics System's period linked birth and infant death files. We included all deaths and births for which there was a reported gestational age at birth on the birth certificate of 22 weeks or greater. The decrease in the infant mortality rate was disaggregated such that all of the change could be attributed to improvements in gestational age-specific infant mortality rates and changes in the distribution of gestational age, by week of gestation, using the Kitagawa method. Sensitivity analyses were performed to account for records in which the obstetric estimate of gestational age was missing and for deaths and births less than 22 weeks' gestation. Maternal race and ethnicity information was obtained from the birth certificate. The infant mortality rates after exclusions were 5.72 and 4.92 per 1000 live births for 2007 and 2013, respectively, with an absolute difference of -0.80 (14% decrease). Infant mortality rates declined by 11% for non-Hispanic whites, by 19% for non-Hispanic blacks, and by 14% for Hispanics during the period. Compared with 2007, the proportion of births in each gestational age category was lower in 2013 with the exception of 39 weeks during which there was an increase in the proportion of births from 30.1% in 2007 to 37.5% in 2013.Gestational age-specific mortality decreased for each gestational age category between 2007 and 2013 except 33 weeks and >42 weeks. About 31% of the decrease in the US infant mortality rate from 2007through 2013 was due to changes in the gestational age distribution, and 69% was due to improvements in gestational age-specific survival.Improvements in the gestational age distribution from 2007 through 2013 benefited infants of non-Hispanic white women (48%) themost, followed by infants of non-Hispanic black (31%) and Hispanic (14%) women. Infant mortality improved between 2007 and 2013 as a result of both improvements in the distribution of gestational age at birth and improvements in survival after birth. The differential contribution of improvements in the gestational age distribution at birth by race and ethnicity suggests that preconception and antenatal health and health care aimed at preventing or delaying preterm birth may not be reaching all populations.

240: Explaining the recent decrease in US infant mortality rate, 2007-2013

ObjectiveBetween 2007 and 2013 the US infant mortality rate declined steadily, along with a decline in the preterm birth rate, from 6.75 to 5.96 deaths per 1000 live births. The aim of this study was to explain the decrease in infant mortality by decomposing the rate difference between 2013 and 2007 into the proportion due to change in the distribution of gestational age and the proportion due to change in gestational age-specific mortality.Study DesignThe US period linked birth-infant death files were used to enumerate births and infant deaths for 2007 and 2013 at each week of gestational age. The proportion of births at each gestational week and the gestational age-specific mortality for each week were calculated. Births and deaths were excluded if gestational age was missing. The Kitagawa decomposition method was used to partition the changes at each gestational week and the overall reduction in infant mortality into the fractions due to change in the distribution of gestational age at birth and to change in the gestational age-specific mortality.ResultsInfant mortality rates were 6.62 and 5.90 for 2007 and 2013 respectively (-0.72 per 1000 livebirths). In general, the proportion of births at preterm gestational ages and the gestational-age specific mortality rates at each gestational age decreased between 2007 and 2013. Decomposing the overall decrease in infant mortality resulted in apportioning 36 percent of the decline to changes in the distribution of gestational age and 64 percent to decreases in gestational age-specific mortality (Table). Patterns were not explained by births and deaths missing gestational age data.Conclusion ObjectiveBetween 2007 and 2013 the US infant mortality rate declined steadily, along with a decline in the preterm birth rate, from 6.75 to 5.96 deaths per 1000 live births. The aim of this study was to explain the decrease in infant mortality by decomposing the rate difference between 2013 and 2007 into the proportion due to change in the distribution of gestational age and the proportion due to change in gestational age-specific mortality. Between 2007 and 2013 the US infant mortality rate declined steadily, along with a decline in the preterm birth rate, from 6.75 to 5.96 deaths per 1000 live births. The aim of this study was to explain the decrease in infant mortality by decomposing the rate difference between 2013 and 2007 into the proportion due to change in the distribution of gestational age and the proportion due to change in gestational age-specific mortality. Study DesignThe US period linked birth-infant death files were used to enumerate births and infant deaths for 2007 and 2013 at each week of gestational age. The proportion of births at each gestational week and the gestational age-specific mortality for each week were calculated. Births and deaths were excluded if gestational age was missing. The Kitagawa decomposition method was used to partition the changes at each gestational week and the overall reduction in infant mortality into the fractions due to change in the distribution of gestational age at birth and to change in the gestational age-specific mortality. The US period linked birth-infant death files were used to enumerate births and infant deaths for 2007 and 2013 at each week of gestational age. The proportion of births at each gestational week and the gestational age-specific mortality for each week were calculated. Births and deaths were excluded if gestational age was missing. The Kitagawa decomposition method was used to partition the changes at each gestational week and the overall reduction in infant mortality into the fractions due to change in the distribution of gestational age at birth and to change in the gestational age-specific mortality. ResultsInfant mortality rates were 6.62 and 5.90 for 2007 and 2013 respectively (-0.72 per 1000 livebirths). In general, the proportion of births at preterm gestational ages and the gestational-age specific mortality rates at each gestational age decreased between 2007 and 2013. Decomposing the overall decrease in infant mortality resulted in apportioning 36 percent of the decline to changes in the distribution of gestational age and 64 percent to decreases in gestational age-specific mortality (Table). Patterns were not explained by births and deaths missing gestational age data. Infant mortality rates were 6.62 and 5.90 for 2007 and 2013 respectively (-0.72 per 1000 livebirths). In general, the proportion of births at preterm gestational ages and the gestational-age specific mortality rates at each gestational age decreased between 2007 and 2013. Decomposing the overall decrease in infant mortality resulted in apportioning 36 percent of the decline to changes in the distribution of gestational age and 64 percent to decreases in gestational age-specific mortality (Table). Patterns were not explained by births and deaths missing gestational age data. Conclusion

Nationwide Birth Weight and Gestational Age-specific Neonatal Mortality Rate in Taiwan

There are limited nationwide data relating to neonatal mortality rate in Taiwan. This study aims to provide updated national birth weight/gestational age-specific neonatal mortality reference rates. We abstracted the birth registration database from the Ministry of Interior in Taiwan from 1998 to 2002 and linked the data to the death registration database from the Ministry of Health and Welfare in Taiwan between 1998 and 2003. We included 1,331,785 infants born between 20 weeks and 44 weeks of gestation and weighing within the median ± 2 interquartile ranges in their age group in this study. We calculated the birth weight/gestational age-specific neonatal mortality rates of different genders by birth weight increments of 250g and at gestational age intervals of 1 week. A Poisson regression model was used in modeling the mortality data. A total of 4,169 deaths occurred within 28 days of life out of a total of 1,331,785 live births between 20 weeks and 44 weeks of gestation, giving a neonatal mortality rate (0-27 days) of 3.39 per 1000 live births for males and 2.80 per 1000 for females. The infant mortality rate remained higher in the male (5.91 per 1000) than the female (5.10 per 1000) population within the 1(st) year of life. Birth weight/gestational age-specific neonatal mortality rates were plotted with curves representing the 10(th) and 90(th) birth weight percentiles. The risk of an early neonatal death (0-6 days) does not exceed 50% except for female neonates<500g and ≤ 23 weeks, which implies that the limit of viability is now at 23 weeks for females. We have provided an easy-to-use birth weight/gestational age-specific neonatal mortality rate chart as a reference document that physicians and parents can use to make decisions based on ethical considerations relating to whether to give palliative care or further invasive management. The normative data are crucial for public health policies on neonatal care in Taiwan.

Understanding declines in stillbirth and neonatal mortality in Europe

Background Fetal and neonatal mortality rates declined in most countries of Europe between 2004 and 2010. We investigated the contribution of changing gestational age distributions and gestational-age specific mortality rates to these declines. Methods Aggregate data on live births, fetal and neonatal deaths by gestational age were collected using a common protocol from countries and regions in the Euro-Peristat project …

169: A Detailed Examination of Infant Mortality Rates in Canada and Selected High Income Countries

Infant mortality rate is a key perinatal health indicator, widely used as an index of population health status. International comparisons of infant mortality rates need to be interpreted with caution. Differences in birth registration criteria are a recognised problem, especially for preterm infants at the borderline of viability. Variations in the reporting of stillbirths/live births are another concern. Varied definitions are used to calculate perinatal mortality rates and this is further complicated by whether induced abortions and terminations of pregnancy are included or excluded. We examined perinatal and infant mortality rates in selected high income countries for evidence of differences in registration practices, classification of stillbirths and live births and selective registration of extremely preterm infants who survive. We carried out a retrospective population-based cohort study using national data from Canada, the United States, Denmark, Finland, Iceland, Norway, and Sweden for the period 1995 to 2005. The main outcome measures included live birth distribution by gestational age and birth weight; gestational age- and birth weight-specific fetal, neonatal, and post-neonatal mortality; and cause-specific (congenital anomalies, immaturity-related and other conditions) infant mortality. Our results show country-specific live birth distributions by birth weight and gestational age, birth weight- and gestational age-specific mortality and cause-specific mortality over a 11 year period, from 1995 to 2005. We observed differences between countries when crude neonatal mortality rates were compared to neonatal mortality excluding near-viable births. Similar results were obtained for stillbirths but not for postneonatal mortality which were essentially unaffected by the exclusion of near-viable births. These findings provide a comprehensive perspective of infant mortality rates in these countries by using specific birth weight and gestational age cut-off values, to preclude artefacts that often arise from such international comparisons. It also highlights the need for standardizing birth registration and infant death registration procedures globally, in order for international comparisons of fetal and infant mortality rates to be more meaningful.

Does advanced maternal age confer a survival advantage to infants born at early gestation?

BackgroundRecent studies have shown that older mothers who deliver at preterm gestation have lower neonatal mortality rates compared with younger mothers who deliver at preterm gestation. We examined the effect of maternal age on gestational age-specific perinatal mortality.MethodsWe compared fetal, neonatal and perinatal mortality rates among singleton births in the United States, 2003–2005, to mothers aged ≥35 versus 20–29 years. The analysis was stratified by gestational age and perinatal mortality rates were contrasted by maternal age at earlier (22–33 weeks) and later gestation (≥34 weeks). Gestational age-specific perinatal mortality rates were calculated using the traditional perinatal formulation (deaths among births at any gestation divided by total births at that gestation) and also the fetuses-at-risk model (deaths among births at any gestation divided by fetuses-at-risk of death at that gestation).Logistic regression was used to estimate adjusted odds ratios (AOR) for perinatal death.ResultsUnder the traditional approach, fetal death rates at 22–33 weeks were non-significantly lower among older mothers (AOR 0.97, 95% confidence interval [CI] 0.91-1.03), while rates were significantly higher among older mothers at ≥34 weeks (AOR 1.66, 95% CI 1.56-1.76). Neonatal death rates were significantly lower among older compared with younger mothers at 22–33 weeks (AOR=0.93, 95% CI 0.88-0.98) but higher at ≥34 weeks (AOR 1.26, 95% CI 1.21-1.31). Under the fetuses-at-risk model, both rates were higher among older vs younger mothers at early gestation (AOR for fetal and neonatal mortality 1.35, 95% CI 1.27-1.43 and 1.31, 95% CI 1.24-1.38, respectively) and late gestation (AOR for fetal and neonatal mortality 1.66, 95% CI 1.56-1.76) and 1.21, 95% CI 1.14-1.29, respectively).ConclusionsAlthough the traditional prognostic perspective on the risk of perinatal death among older versus younger mothers varies by gestational age at birth, the causal fetuses-at-risk model reveals a consistently elevated risk of perinatal death at all gestational ages among older mothers.

Gestational Age Patterns of Fetal and Neonatal Mortality in Europe: Results from the Euro-Peristat Project

BackgroundThe first European Perinatal Health Report showed wide variability between European countries in fetal (2.6–9.1‰) and neonatal (1.6–5.7‰) mortality rates in 2004. We investigated gestational age patterns of fetal and neonatal mortality to improve our understanding of the differences between countries with low and high mortality.Methodology/Principal FindingsData on 29 countries/regions participating in the Euro-Peristat project were analyzed. Most European countries had no limits for the registration of live births, but substantial variations in limits for registration of stillbirths before 28 weeks of gestation existed. Country rankings changed markedly after excluding deaths most likely to be affected by registration differences (22–23 weeks for neonatal mortality and 22–27 weeks for fetal mortality). Countries with high fetal mortality ≥28 weeks had on average higher proportions of fetal deaths at and near term (≥37 weeks), while proportions of fetal deaths at earlier gestational ages (28–31 and 32–36 weeks) were higher in low fetal mortality countries. Countries with high neonatal mortality rates ≥24 weeks, all new member states of the European Union, had high gestational age-specific neonatal mortality rates for all gestational-age subgroups; they also had high fetal mortality, as well as high early and late neonatal mortality. In contrast, other countries with similar levels of neonatal mortality had varying levels of fetal mortality, and among these countries early and late neonatal mortality were negatively correlated.ConclusionsFor valid European comparisons, all countries should register births and deaths from at least 22 weeks of gestation and should be able to distinguish late terminations of pregnancy from stillbirths. After excluding deaths most likely to be influenced by existing registration differences, important variations in both levels and patterns of fetal and neonatal mortality rates were found. These disparities raise questions for future research about the effectiveness of medical policies and care in European countries.

Perinatal care at the limit of viability between 22 and 26 completed weeks of gestation in Switzerland

Perinatal care of pregnant women at high risk for preterm delivery and of preterm infants born at the limit of viability (22-26 completed weeks of gestation) requires a multidisciplinary approach by an experienced perinatal team. Limited precision in the determination of both gestational age and foetal weight, as well as biological variability may significantly affect the course of action chosen in individual cases. The decisions that must be taken with the pregnant women and on behalf of the preterm infant in this context are complex and have far-reaching consequences. When counselling pregnant women and their partners, neonatologists and obstetricians should provide them with comprehensive information in a sensitive and supportive way to build a basis of trust. The decisions are developed in a continuing dialogue between all parties involved (physicians, midwives, nursing staff and parents) with the principal aim to find solutions that are in the infant's and pregnant woman's best interest. Knowledge of current gestational age-specific mortality and morbidity rates and how they are modified by prenatally known prognostic factors (estimated foetal weight, sex, exposure or nonexposure to antenatal corticosteroids, single or multiple births) as well as the application of accepted ethical principles form the basis for responsible decision-making. Communication between all parties involved plays a central role. The members of the interdisciplinary working group suggest that the care of preterm infants with a gestational age between 22 0/7 and 23 6/7 weeks should generally be limited to palliative care. Obstetric interventions for foetal indications such as Caesarean section delivery are usually not indicated. In selected cases, for example, after 23 weeks of pregnancy have been completed and several of the above mentioned prenatally known prognostic factors are favourable or well informed parents insist on the initiation of life-sustaining therapies, active obstetric interventions for foetal indications and provisional intensive care of the neonate may be reasonable. In preterm infants with a gestational age between 24 0/7 and 24 6/7 weeks, it can be difficult to determine whether the burden of obstetric interventions and neonatal intensive care is justified given the limited chances of success of such a therapy. In such cases, the individual constellation of prenatally known factors which impact on prognosis can be helpful in the decision making process with the parents. In preterm infants with a gestational age between 25 0/7 and 25 6/7 weeks, foetal surveillance, obstetric interventions for foetal indications and neonatal intensive care measures are generally indicated. However, if several prenatally known prognostic factors are unfavourable and the parents agree, primary non-intervention and neonatal palliative care can be considered. All pregnant women with threatening preterm delivery or premature rupture of membranes at the limit of viability must be transferred to a perinatal centre with a level III neonatal intensive care unit no later than 23 0/7 weeks of gestation, unless emergency delivery is indicated. An experienced neonatology team should be involved in all deliveries that take place after 23 0/7 weeks of gestation to help to decide together with the parents if the initiation of intensive care measures appears to be appropriate or if preference should be given to palliative care (i.e., primary non-intervention). In doubtful situations, it can be reasonable to initiate intensive care and to admit the preterm infant to a neonatal intensive care unit (i.e., provisional intensive care). The infant's clinical evolution and additional discussions with the parents will help to clarify whether the life-sustaining therapies should be continued or withdrawn. Life support is continued as long as there is reasonable hope for survival and the infant's burden of intensive care is acceptable. If, on the other hand, the health care team and the parents have to recognise that in the light of a very poor prognosis the burden of the currently used therapies has become disproportionate, intensive care measures are no longer justified and other aspects of care (e.g., relief of pain and suffering) are the new priorities (i.e., redirection of care). If a decision is made to withhold or withdraw life-sustaining therapies, the health care team should focus on comfort care for the dying infant and support for the parents.

The natural history of pregnancy: diseases of early and late gestation

To identify the disease processes underlying the increasing rate of gestational age-specific perinatal mortality observed under the fetuses-at-risk model. Retrospective cohort study. USA and Nova Scotia, Canada. Births in the USA (1995 and 2005) and Nova Scotia, Canada (1988-2007). Incidence rates of perinatal death and serious neonatal morbidity were calculated using the fetuses-at-risk approach (e.g. cumulative incidence of stillbirth during any gestational week per 1000 fetuses at risk of stillbirth). Perinatal mortality and serious neonatal morbidity. Perinatal mortality rates increased with advancing gestation. Rates of bronchopulmonary dysplasia, intraventricular haemorrhage, periventricular leucomalacia and retinopathy of prematurity were highest in early gestation, whereas rates of meconium aspiration syndrome and aspiration pneumonitis were highest at late term and post-term gestation. Respiratory depression (i.e. delay in initiating and maintaining respiration after birth, low 5-minute Apgar score or seizures caused by neonatal encephalopathy) showed an increase from 34 weeks onwards. The increase in perinatal mortality rates at late gestation was congruent with increases in respiratory depression. Other findings included a high incidence of respiratory distress syndrome at late gestation, a nonspecific pattern in the gestational age-specific rates of necrotising enterocolitis and high rates of sudden infant death syndrome at late gestation. The natural history of pregnancy is characterised by diseases of early and late gestation, with the latter largely determining patterns of gestational age-specific perinatal mortality. These findings have implications for obstetric theory and provide insight into various contemporary phenomena, including the rise in iatrogenic late preterm birth.

Extremely Preterm Infant Mortality Rates and Cesarean Deliveries in the United States

To estimate trends in infant mortality rates and cesarean delivery rates for extremely preterm infants born in the United States. This national population-based study used public data from the Centers for Disease Control and Prevention to investigate extremely preterm infants born alive between 22 0/7 and 27 6/7 weeks of gestational age from 1999 to 2005. There were 177,552 extremely preterm infant births (fewer than 1% of all births) from 1999 to 2005. The number of annual extremely preterm births increased by 7% compared with a 4.5% increase for births at all gestations. During the study years, the extremely preterm infant mortality rate (percentage of infants who died in the first year) remained steady (range 33-34%; P=.22), whereas the cesarean delivery rate increased from 43% to 54% (P<.001). The infant mortality rate after cesarean delivery increased from 24% to 26% (P=.012). At each gestational age, the annual cesarean delivery rate increased over time (P<.001 for each), whereas gestational age-specific infant mortality rates were unchanged except for a 2% decline from 2004 to 2005 for infants born at 24 weeks of gestation (P=.01). A significant rise in the cesarean delivery rate in the United States from 1999 to 2005 for infants born at less than 28 weeks of gestation was not associated with an improvement in the infant mortality rate.

A nationwide investigation on gestational age specific birthweight and mortality among Japanese twins

Gestational age specific birthweight has been used as an important indicator to identify the health status of neonates and to provide appropriate neonatal care services to those at high risk. To identify the gestational age specific birthweight of twins born in secondary and tertiary hospitals in Japan and to explore factors affecting mortality, we used a nationwide obstetric database in Japan. Liveborn twins from 2001 to 2005 in the database, which was established with the national Perinatal Health Care Project, were enrolled (n=22,240). Obstetric data from the medical records were collected and analysed. Approximately 60% of liveborn twins were delivered between weeks 33 and 38, most frequently at 36 and 37 weeks. The mean birthweight of liveborn twins was 2084 g and the mean gestational age was 34.9 weeks. Intrauterine growth differed by parity, mode of delivery, birth order, chorionicity and sex. Using logistic regression, lower gestational age, small for gestational age, monochorionic twins and vaginal delivery tended to have higher risks of mortality.