Gestational Age Distribution Research Articles

Guidelines on transfusion for fetuses, neonates and older children.

Guidelines on transfusion for fetuses, neonates and older children.

Preterm Births in Peking Union Medical College Hospital in the Past 25 Years.

Objective To investigate the changes in preterm birth rate,its gestational age distribution,and possible contributors in Peking Union Medical College Hospital (PUMCH) over the last 25-year period. Methods The clinical data of premature deliveries,both singleton and twins,in PUMCH from January 1,1990 to December 31,2014 were retrospectively analyzed. We counted the number of premature fetuses and assessed the changes of preterm birth rate and its gestational age distribution (including extremely preterm birth,early preterm birth,and late preterm birth) over time. The etiologies (including spontaneous and iatrogenic) of preterm birth were also surveyed. Results The overall preterm birth rate was 7.8% in PUMCH,showing a slightly up-trend in both singletons and twins. Twin prematurity accounted for 23.8% of total preterm births,increased from 15.1% to 28.5%. Preterm births subgrouped by gestational age included 26 cases (0.7%) of extreme prematurity (<28 weeks),1199 cases (33.9%) of early preterm birth (28- 33+6 weeks),and 2310 cases (65.3%) of late preterm birth (34- 36+6 weeks). The gestational age distribution in singletons and twins showed no significant difference(z=0.844,P=0.398). Changes in the proportion of preterm birth before 28 weeks was little,gradually increased in the 28- 33+6 weeks group (from 23.8% to 36.1%) and gradually decreased in the 34- 36+6 weeks group (from 75.5% to 63.3%). Trends of gestational age distribution of singleton and twins were similar to that of the total. Spontaneous preterm labor,preterm premature rupture of membrane,and medically indicated (iatrogenic) preterm birth accounted for 20.2%,38.9%,and 40.9% respectively. There was no difference in singletons and twins(χ2=1.071,P=0.301).The proportion of iatrogenic preterm was increased. Common reasons for iatrogenic preterm birth included gestational hypertension,fetal indications (including fetal distress,fetal growth restriction),placenta previa,and pregnancy complicated by heart disease. Conclusions The overall preterm birth rate shows an upward trend in the general hospital as a result of more multifetal gestations and more medically indicated preterm births. Reducing multifetal gestations and effective control of pregnancy complications should be the priorieties in preterm birth intervention.

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.

Commensurate Priors on a Finite Mixture Model for Incorporating Repository Data in Clinical Trials

ABSTRACTDocosahexaenoic acid (DHA) is a good source of fat that can be taken up through food, such as fish, or taken as a supplement. Evidence is building that DHA provides a high-yield, low-risk strategy to reduce preterm birth and/or low birth weight. These births are great costs to society. A recently completed Phase III trial revealed that higher birth weight and gestational age were associated with DHA dosed at 600 mg/day. In this article, we take a posterior predictive approach to assess impacts of these findings on public health. Simple statistical models are not adequate for accurate posterior predictive distribution estimation. Of particular interest is that the joint distribution of birth weight and gestational age is well modeled by a finite mixture of three normal distributions. Data from our own clinical trial exhibit similar features. Using the mean and variance-covariance matrices from a previous study and flexible commensurate priors for the mixing parameters, we estimate the effect of DHA supplementation on over 20,000 infants born in hospitals demographically similar to the hospital where the clinical trial was conducted.

Delivery room management of extremely preterm infants: the EPIPAGE-2 study

ObjectiveTo analyse the delivery room management of babies born between 22 and 26 weeks of completed gestational age and to identify the factors associated with the withholding or withdrawal of...

Clinical features of infants treated for severe retinopathy of prematurity: 8-yearstudy from a large tertiary neonatal intensive care unit in Turkey.

The aim of this study was to report the gestational age (GA) and birth weight (BW) distribution of premature babies who needed treatment for retinopathy of prematurity (ROP) and to assess the timing of the treatment. The records of 9008 infants who were screened for ROP were examined and 556 infants who underwent laser therapy for ROP were reviewed. Sex, GA, BW, postnatal age, and postmenstrual (PM) age at the time of laser therapy were recorded. The babies were classified as in-born (Group 1) and out-born infants (Group 2). The mean GA was 27.3 weeks (range: 22-33 weeks) and the mean BW was 991.1 g (range: 520-2160 g). Of the treated infants, 7.0% were born later than 32 weeks and 8.3% were born over 1500 g. The mean postnatal age was 9.48 weeks (range: 5-22 weeks) and the mean PM age was 36.72 weeks (range: 29-48 weeks) at the time of treatment. Mean BWs and GAs were significantly higher and the mean postnatal age at the time of laser therapy was significantly earlier in Group 2. Infants with severe ROP had a wider range of BWs and GAs compared to those from developed countries and earlier treatment was needed for out-born infants.

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

447: Increased in planned deliveries contribute to a reduction pregnancy hypertension rates in Australia

To explore whether increases in planned deliveries explain declining rates of pregnancy hypertension in Australia. Population-based record linkage cohort study. From 2001 through 2012, among 1,076,122 deliveries, the rate of pregnancy hypertension (including gestational hypertension, preeclampsia and eclampsia) declined by 22% from 9.9% to 7.7% and preeclampsia by 27% from 3.3% to 2.4% (trend P<0.001). Contemporaneously, planned deliveries (labor induction and prelabor cesarean) increased from 38% to 46% of all deliveries and the proportion occurring at 37-39 weeks increased from 47% to 59%. During the study period, changes in the maternal risk factors for pregnancy hypertension were mostly in a direction that would likely increase the rate of pregnancy hypertension, including increased (P<0.01) nulliparity, age ≥35 years, diabetes, overweight/obesity, and use of assisted reproductive technologies. However trends that might decrease pregnancy hypertension rates also occurred with a decrease in multi-fetal pregnancies, age <20 years, autoimmune diseases and previous pregnancy hypertension. Among women who did not develop pregnancy hypertension, the established risk factors for pregnancy hypertension were positively associated with planned births at 37-39 weeks. An overall left shift in the gestational age distribution was not observed among women with pregnancy hypertension, rather a decline in birth rates at all gestations was seen from 38 weeks. Gestational age-specific pregnancy hypertension rates declined from 38 weeks onwards, most steeply at ≥41 weeks (see Figure). Based on changes in the prevalence of maternal risk factors, the pregnancy hypertension rate was predicted to increase to 10.5%. At least 36% of the decline in pregnancy hypertension was explained by early planned births. Increases in early planned delivery for reasons other than hypertension explain part of the observed decline in pregnancy hypertension rates in Australia.

Linkage of population-level administrative hospital data to assess maternal factors affecting infant and child health

BackgroundLinkage of longitudinal administrative data for mothers and babies allows assessment of maternal factors that affect child health outcomes. Linkage between maternity and children's datasets in England is being developed by the Health and Social Care Information Centre and will add to evidence from similar linked data in smaller populations including Scotland, UK, and Ontario, Canada, but will only include prospective data. We established the feasibility of creating a retrospective, linked birth-cohort using non-disclosive clinical variables in administrative data from English hospitals. MethodsRecords of babies and mothers admitted to English National Health Service hospitals from April 1, 2012, to March 31, 2013, were extracted from Hospital Episode Statistics. Baby and maternal records were linked using delivery information shared in both records, and the success of deterministic and probabilistic linkage methods was compared. Erroneous values of birth weight and gestation were identified with gestation-specific reference values. Representativeness of the linked birth cohort was assessed by comparison of key characteristics with national published data (Office for National Statistics). χ2 tests were used to compare proportions of records in each group. Linkage was performed with code written in Stata (version 13); computational effort was insubstantial for the number of records involved. FindingsOf the 672 644 baby records extracted, 280 470 (42%) were linked deterministically to a maternal record when indirect identifiers were used: hospital, general practice, maternal age, birthweight, gestation, birth order, and sex. After probabilistic methods incorporating additional variables that could differ between mother and baby records (admission dates, ethnicity, three or four-character postcode district) or included missing values (delivery data), the final linked cohort captured about 97% of the 678 712 births in English hospitals during 2012. After data cleaning, no significant differences were seen between distributions of sex, gestational age, birthweight, and maternal age according to published national data. InterpretationProbabilistic linkage of indirect identifiers allowed information on maternal and baby health-care trajectories to be combined on a national level without increasing disclosure. These linked data have the potential to provide insight into how prenatal and postnatal maternal health affects child health outcomes. The large sample size and representative population offer power to investigate important subgroups such as preterm birth. FundingThis work was supported by funding from the Wellcome Trust (grant number WT103975/Z/14/).

Increased planned delivery contributes to declining rates of pregnancy hypertension in Australia: a population-based record linkage study

ObjectiveSince the 1990s, pregnancy hypertension rates have declined in some countries, but not all. Increasing rates of early planned delivery (before the due date) have been hypothesised as the reason...

The association between temporal changes in the use of obstetrical intervention and small-for-gestational age live births.

BackgroundThe literature attributes secular declines in small-for-gestational age (SGA) live births to changes in maternal smoking and other maternal characteristics. However, there are reasons to believe that the observed reductions in SGA may be a consequence of early delivery following obstetric intervention.MethodsWe examined temporal trends in obstetrical intervention and SGA among singleton live births in the United States from 1990 to 2010. The modified Kitagawa decomposition, based on the fetuses-at-risk approach, was used to assess the relative contribution of changes in the gestational age distribution and gestational age-specific SGA to overall changes in SGA. Reductions in SGA rates due to a left shift in the gestational age distribution were assumed to primarily reflect increased obstetrical intervention, whereas decreases in overall SGA due to decreases in gestational-age-specific SGA rates were assumed to reflect declines in risk factors.ResultsTemporal trends in SGA followed a non-linear pattern, with substantial declines from 10.1 % in 1990–92 to 8.9 % in 2002–04, followed by a small increase to 9.1 % in 2008–10. Rates of maternal smoking steadily decreased throughout the same time period and changes in SGA rates were more consistent with changes in the gestational age distribution. The modified Kitagawa decomposition analysis also attributed the initial decline in SGA rates to changes in the gestational age distribution.ConclusionsComplex temporal pattern in SGA rates cannot be explained by the linear pattern of changes in factors like maternal smoking. Changes in the gestational age distribution are more consistent with the observed secular trends in SGA rates.

G537(P) Prospective re-audit of central line associated bloodstream infections on the neonatal unit following guideline implementation

Context This audit was carried out in Wrexham Maelor Hospital’s (WMH) neonatal unit (NNU) and conducted by the authors (two FY2 doctors and Staff Grade paediatrician). The guideline which has been implemented was approved by both medical and nursing teams. Problem A prospective audit performed in 2010–2011 showed that Wrexham Maelor Hospital’s (WMH) neonatal unit (NNU) had a high rate of central-line associated bloodstream infections (CLABSI) as compared to the rate reported by Centres for Disease Control and Prevention (USA). CLABSI have a high cost in terms of both morbidity and financial expenditure, and are preventable. Assessment of problem and analysis of its causes To quantify the problem the infection rate was expressed as number of central lines days per one CLABSI. CLABSI was defined as growth of the same organism in blood and central line tip cultures (obtained within 48 hrs of each other). The causes of CLABSI were assessed using CDC recommendations (Guideline for the prevention of intravascular catheter-related infections, 2011, CDC, USA). To impose the changes, CDC recommendations were adapted, local guideline developed and medical and nursing staff educated. Intervention A guideline was introduced in January 2013 that recommended use of 0.5% chlorhexidine in 70% alcohol (Hydrex® Pink), “check and do” list for clinicians, purchase of bundled supplies, continuous staff education, and nurse empowerment to stop non-urgent insertions if proper procedures were not followed. Study design This was a prospective re-audit. Strategy for change The “check-and-do” list was approved by the medical and nursing teams. The results of the initial audit were presented to the paediatric team along with the new guideline. It was agreed that the guideline would be followed and completed and list inserted into the notes of every patient who had a central line inserted from June 2013 onwards. The re-audit looked at the rate of CLABSI for all central lines (long lines, umbilical venous catheters [UVCs] and umbilical arterial catheters [UACs]) inserted between June 2013 and May 2014, and was prospective. Measurement of improvement The results of these pre- and post-guideline audits were compared. The CLABSI rate in the pre-guideline audit was 10 in 179 long line days. In the re-audit, the CLABSI rate was 0 in 201 long line days, and 3 in 530 all central line days (long lines, UVCs and UACs; Note the pre-guideline audit only looked at infections associated with long lines). The difference between the distributions of gestational age in the audits was non-significant (Mann-Whitney test). Effects of changes The re-audit data showed that the rate of CLABSI in the NNU have significantly decreased since the implementation of the guideline. CLABSI-associated morbidity and mortality have also decreased, which clearly benefited the patient group. Lessons learnt It is helpful when implementing change and new guidance to work as a multi-disciplinary team. We found that by doing so, the new guidance was well received and adhered to. Message for others We would recommend that all neonatal units establish an ongoing audit of CLABSI, and produce a guideline and check and do list if there is not already one in use. Our experience showed that significant reduction in CLABSI rate can be achieved in a relatively small NNU, over a relatively short time scale with similar effectiveness to that shown in larger NNUs and with close to zero additional costs.

Spatial and temporal patterns in preterm birth in the United States.

Despite years of research, the etiologies of preterm birth remain unclear. In order to help generate new research hypotheses, this study explored spatial and temporal patterns of preterm birth in a large, total-population dataset. Data on 145 million US births in 3,000 counties from the Natality Files of the National Center for Health Statistics for 1971-2011 were examined. State trends in early (<34 wk) and late (34-36 wk) preterm birth rates were compared. K-means cluster analyses were conducted to identify gestational age distribution patterns for all US counties over time. A weak association was observed between state trends in <34 wk birth rates and the initial absolute <34 wk birth rate. Significant associations were observed between trends in <34 wk and 34-36 wk birth rates and between white and African American <34 wk births. Periodicity was observed in county-level trends in <34 wk birth rates. Cluster analyses identified periods of significant heterogeneity and homogeneity in gestational age distributional trends for US counties. The observed geographic and temporal patterns suggest periodicity and complex, shared influences among preterm birth rates in the United States. These patterns could provide insight into promising hypotheses for further research.

The Association Between HIV Status and Antenatal Care Attendance Among Pregnant Women in Rural Hospitals in Lesotho

Early and frequent antenatal clinic (ANC) attendance is important for promotion of healthy outcomes for mother and child. This study explored the relationship between HIV status at the first ANC visit and subsequent ANC attendance among pregnant women in Lesotho. A retrospective review of ANC records from a cohort of pregnant women attending their first ANC visit in December 2009 to May 2010 in 3 rural hospitals was conducted. Wilcoxon rank sum tests compared the distribution of gestational age (GA) and ANC visit number by HIV status. Records from 728 women were reviewed with mean GA at the first ANC visit of 22.3 weeks (SD = 7.2) and 2.7 (SD = 1.4) mean number of ANC visits per woman. Neither number of visits nor GA at first visit differed between HIV-positive and HIV-negative women. In total, 33.9% of women completed 4 ANC visits. Women with documented HIV-positive status before ANC were more likely to present early to ANC than all other women (18.8 vs. 22.6 weeks, adjusted odds ratio = 2.54, 95% confidence interval: 1.41 to 4.57). Geographical region, increasing maternal age, and lower parity were associated with completion of expected ANC visits among all women. Increasing maternal age and CD4 count were associated with completion of expected visits among HIV-positive women. In Lesotho, number of subsequent visits did not differ between women testing HIV-positive and HIV-negative in ANC. However, women with documented HIV-positive status attended ANC earlier than women who were tested in ANC. HIV testing and counseling, particularly for HIV-positive women before pregnancy, can promote early ANC attendance.

Commentary: from estimation to translation: interpreting mediation analysis results in perinatal epidemiology.

Commentary: from estimation to translation: interpreting mediation analysis results in perinatal epidemiology.

Heat, Air Pollution and Preterm Birth: Which Weeks of Gestation Are Susceptible? The Rome and Barcelona Birth Cohorts

INTRODUCTION Environmental exposures have been linked to preterm birth but which weeks of gestation (WOG) are more susceptible is still unexplored. OBJECTIVE To estimate the effect of maximum apparent temperature (MAT) and air pollution levels on preterm birth risk by WOG and the distribution of WOG under different MAT scenarios. MATERIALS AND METHODS All singleton live-births born in the warm season in Rome (2001-2010) and Barcelona (2007-2012) were used. A Cox regression model was used to link MAT, PM10, O3 and NO2 to preterm birth adjusting for temporal, demographic and maternal variables. Hazard Ratios (HR) of giving birth per 1 unit increase of each exposure are reported by WOG. We included Inverse Probability Weights (IPW) to adjust for variations of at risk population over WOG. Finite mixture model (FMM) estimated gestational age distributions under different MAT average values. RESULTS We observed 132,691 and 67,030 births in Rome and Barcelona (5.5% preterm).The effect of MAT significantly decreased with increasing gestational age in both cities. The HR between the 22nd- 26th WOG were 1.065 (95%CI: 1.047-1.083) and 1.077 (95%CI: 1.053-1.102) in Rome and Barcelona, while in the 36th WOG they decreased to 1.026 (95%CI: 1.021-1.032) and 1.024 (IC95%: 1.017-1.030). The effects of PM10, NO2 and O3 also showed a significant decreasing trend with gestational age. The FMM showed a change in the distribution of gestational age when comparing average MAT of 20°C with 37°C in both cities, with a shift towards shorter gestation in the hotter temperature scenario. CONCLUSION Earliest WOG resulted to be more susceptible to environmental exposures for preterm risk. Public health and clinicians should consider this information to better target prevention.

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 …

Exposure to elevated temperatures and risk of preterm birth in Valencia, Spain

BackgroundPrematurity is the second-leading cause of death in children under the age of 5 worldwide. It is predicted that the future climate will have more intense, longer lasting and frequent extreme heat episodes, and so the temperature effect on the risk of preterm birth is generating considerable interest in the public health field. Our aim was to explore the potential short-term effects of elevated temperatures on the risk of preterm birth in Valencia (Spain). MethodsAll singleton natural births born in the metropolitan area of Valencia during the warm season (May–September, 2006–2010) were included (N=20,148). We applied time-series quasi-Poisson generalized additive models to evaluate the risk of preterm birth at different maximum apparent and minimum temperature values (50th, 90th and 99th percentiles of the warm season) up to 3 weeks before delivery (reference: overall annual median value). In addition, three temperature-interval-specific estimates were obtained for changes between each of these temperature values. We took into account the pregnancies at risk adjusted by the gestational age distribution of the set in each day. We used distributed-lag non-linear models with a flexible function in the shape of the relationship and lag structure. ResultsRisk of preterm birth increased up to 20% when maximum apparent temperature exceeded the 90th percentile two days before delivery and 5% when minimum temperature rose to the 90th percentile in the last week. Differences between interval-specific risk estimates across lags were observed. ConclusionExposure to elevated temperatures was associated with an increased risk of preterm birth in the following three weeks.

Amnioinfusion in very early preterm prelabor rupture of membranes (AMIPROM): pregnancy, neonatal and maternal outcomes in a randomized controlled pilot study

To assess short- and long-term outcomes of pregnant women with very early rupture of membranes randomized to serial amnioinfusion or expectant management, and to collect data to inform a larger, more definitive clinical trial. This was a prospective non-blinded randomized controlled trial with randomization stratified for pregnancies in which the membranes ruptured between 16 + 0 and 19 + 6 weeks' gestation and 20 + 0 and 23 + 6 weeks' gestation to minimize the risk of random imbalance in gestational age distribution between randomized groups. Intention-to-treat analysis was used. The study was conducted in four UK hospital-based fetal medicine units (Liverpool Women's NHS Trust, St Mary's Hospital Manchester, Birmingham Women's NHS Foundation Trust and Wirral University Hospitals Trust). The participants were women with confirmed preterm prelabor rupture of membranes at 16 + 0 to 24 + 0 weeks' gestation. Women with multiple pregnancy, fetal abnormality or obstetric indication for immediate delivery were excluded. Participants were randomly allocated to either serial weekly transabdominal amnioinfusions if the deepest pool of amniotic fluid was < 2 cm or expectant management until 37 weeks' gestation. Short-term maternal, pregnancy and neonatal and long-term outcomes for the child were studied. Long-term respiratory morbidity was assessed using validated respiratory questionnaires at 6, 12 and 18 months of age and infant lung function test at around 12 months of age. Neurodevelopment was assessed using the Bayley Scales of Infant Development, second edition (BSID-II) at corrected age of 2 years. Fifty-eight women were randomized to the study. Two babies were excluded from the analysis because of termination of pregnancy for lethal anomaly, leaving 56 participants (28 assigned to serial amnioinfusion and 28 to expectant management) recruited between 2002 and 2009. There was no significant difference in perinatal mortality (19/28 vs 19/28; relative risk (RR) 1.0 (95% CI, 0.70-1.43)) and maternal or neonatal morbidity. The overall chance of surviving without long-term respiratory or neurodevelopmental disability was 4/56 (7.1%); 4/28 (14.3%) in the amnioinfusion group and 0/28 in the expectant group (RR 9.0 (95% CI, 0.51-159.70)). This pilot study found no major differences in maternal, perinatal or pregnancy outcomes. The study was not designed to show a difference between the groups and the number of survivors was too small to draw any conclusions about long-term outcomes. It does, however, signal that a larger definitive study to evaluate amnioinfusion for improvement in healthy survival is needed. The pilot suggests that, with appropriate funding, such a study is feasible.

Too heavy, too late: investigating perinatal health outcomes in immigrants residing in Spain. A cross-sectional study (2009–2011)

BackgroundStudies have shown that immigrants residing in Spain have lower risks of delivering low birthweight (LBW) and preterm babies despite their socioeconomic disadvantages (the healthy migrant paradox). However, less is...