Fetal Infant Mortality Research Articles

Refreshing the Perinatal Periods of Risk: A New Reference Group and Nationwide Large-County-Level Analyses.

The Perinatal Periods of Risk approach (PPOR) is designed for use by communities to assess and address the causes of high fetal-infant mortality rates using vital records data. The approach is widely used by local health departments and their community and academic partners to inform and motivate systems changes. PPOR was developed and tested in communities based on data years from 1995 to 2002. Unfortunately, a national reference group has not been published since then, primarily due to fetal death data quality limitations. This paper assesses data quality and creates a set of unbiased national reference groups using 2014-2016 national vital records data. Phase 1 and Phase 2 analytic methods were used to divide excess mortality into six components and create percentile plots to summarize the distribution of 100 large US counties for each component. Eight states with poor fetal death data quality were omitted from the reference groups to reduce bias due to missing maternal demographic information. There are large Black-White disparities among reference groups with the same age and education restrictions, and these vary by component. PPOR results vary by region, maternal demographics, and county. The magnitude of excess mortality components varies widely across US counties. New national reference groups will allow more communities to do PPOR. Percentile plots of 100 large US counties provide an additional benchmark for new communities using PPOR and help emphasize problem areas and potential solutions.

566: Optimal timing of delivery in women age 40 and over

The number of women of advanced maternal age is increasing. In order to determine optimal delivery timing, the risk of stillbirth and infant death in women aged 40 and over was calculated for each gestational age at term. This is a population-based retrospective cohort study using US birth certificate data. Singleton live births and stillbirths of women aged ≥ 40 who delivered at term between January 2007 and December 2013 were included. Women with pre-gestational diabetes, hypertension or fetal anomalies were excluded. Maternal age was stratified into two groups: women aged 40-44 and women aged ≥ 45. At each gestational age the prospective stillbirth risk, the infant mortality risk, and the composite fetal-infant mortality risk of each additional week of expectant management were calculated (Figure 1). We considered the optimal gestational age of delivery to be when the infant mortality was less than the composite risk of expectant management for one additional week. There were 23,589,521 births included in the analysis; 23,519,868 live births, 22,234 stillbirths, and 47,419 infant deaths. In women ≥ 40 years, the composite risk of expectant management until 40 weeks exceeded the risk of infant death at 39 weeks (63.2 composite risk vs 15.6 infant deaths per 10,000, p< 0.001). When the data was stratified by maternal age, the risk beyond 39 weeks was greater in women ≥ 45years (113.4 composite risk vs 14.7 infant deaths per 10,000, p< 0.001) as well as in women age 40-44 (60.4 composite risk vs 15.6 infant deaths per 10,000, p< 0.001). For women aged ≥45, the number of women was small, and our data suggests a trend toward increasing risk of mortality with expectant management beyond 38 weeks, although this was not statistically significant (29.8 composite risk vs 18.8 infant deaths per 10,000, p=0.130). Delivery at 39 weeks minimizes stillbirth and infant mortality risk for women age over 40, and in particular in women aged over 45. This study suggests a trend favoring delivery at 38 weeks in women aged over 45 in order to minimize risk of fetal and infant death.View Large Image Figure ViewerDownload Hi-res image Download (PPT)

Optimal time of delivery to reduce the risk of infant mortality in small and normally grown fetuses: A national cohort study in Korea.

PurposeTo examine the competing risks of stillbirth versus infant death and to evaluate the optimal time of delivery in the population of small for gestational age (SGA) and non-SGA late preterm and term fetuses.MethodsThis was a retrospective national cohort study of all singleton births between 34 0/7 and 42 6/7 weeks of gestation using the Korean vital statistics (n = 2,106,159). We compared the risk of infant mortality with a composite of fetal–infant mortality risk that would occur after expectant management for one additional week and evaluated the optimal time of delivery, in SGA and non-SGA pregnancies.ResultsIn the total population, the risk of expectant management became significantly higher than the risk of delivery, at 39 weeks and beyond, similar with non-SGA group. In the SGA group, the risk of stillbirth was significantly greater at all GAs than for non-SGA pregnancies, and the risk of infant death was significantly increased until 38 weeks (25.8 per 10,000 live births, 95% CI 20.11–32.47), and the risk of stillbirth was significantly increased at 41 weeks (11.65 per 10,000 ongoing pregnancies, 95% CI 6.95–18.09), compared to 39 weeks (12 per 10,000 live births, 95% CI 8.98–15.64 and 5.12 per 10,000 ongoing pregnancies, 95% CI 3.84–6.66, respectively).ConclusionIn Korean women, delivery between 39 and 41 weeks minimizes fetal/infant mortality, in non-SGA pregnancies. In uncomplicated SGA pregnancies, delivery between 39 and 40 weeks can be considered to decrease risk of infant death and stillbirths.

Practice of pathological examinations in stillbirths: A 10-year retrospective study

To describe the practice of fetal and placental pathological examinations in a large series of spontaneous stillbirths over 10 years. Inclusion of cases recorded by the Lower Normandy Regional Fetal-Infant Mortality Observatory (observatoire régional de mortalité fœto-infantile) from January 1, 2005 to December 31, 2014. The possible cause of death was coded in accordance with the ReCoDe classification system. Seven hundred and forty-four cases were recorded. The placental examinations were conducted in 93.7% of cases (CI95%[91.7-95.3]), increasing over the study period, and an autopsy was proposed in 87.2% of cases (CI95%[84.8-89.6]). Autopsy was conducted less frequently during the most recent period, with parental refusal increasing over time. In multivariate analysis, no factor was associated with a higher frequency of placental examinations, while autopsy was proposed more often under certain circumstances: less than 4 pregnancies (P<10-2), birth weight from 1000 to 1500 grams (P=0.05), singleton (P<10-2), clinical context not suggesting a cause (P<10-3), type 1 or 2 maternity ward (P<10-2), antepartum death (P<10-3). Placental analysis was almost systematically realized, as suggested by international guidelines. Fetal autopsy was often performed, however only in some specific circumstances. New practice guidance to realize customized fetal autopsies appear to be necessary.

Three alternative methods to resolve paradoxical associations of exposures before term.

To propose three methods to estimate associations between pregnancy exposures and outcomes before term, including the association between preeclampsia and preterm fetal-infant mortality, while avoiding the selection bias found in conventional analytic designs. Population-level analysis of 1,099,839 women who delivered live or stillborn infants in Quebec hospitals from 1989 to 2012, covering nearly a quarter of Canadian births. The exposure of interest was preeclampsia at 20-29, 30-33, 34-36, and ≥37weeks of gestation. We compared preeclamptic with non-preeclamptic pregnancies in parametric survival models with a Weibull distribution using three analytic designs: (1) fetuses-at-risk; (2) bias correction factors; and (3) analysis of pregnancies at high risk of preterm delivery. Main outcome measures were occurrence of fetal or postnatal infant death before discharge. In models affected by bias due to selection of preterm births, women with preeclampsia early in gestation had paradoxically lower risks of fetal and infant mortality than women without preeclampsia. All three analytic approaches reversed the associations, showing a harmful effect of preeclampsia before term. At 20-29weeks, for example, preeclampsia was associated with 1.35 times the risk of infant mortality (95% confidence interval 1.14-1.60) and 1.40 times the risk of stillbirth (95% confidence interval 1.18-1.67) with the fetuses-at-risk approach. Paradoxically protective benefits of exposures such as preeclampsia before term are artifacts of inappropriate analytic design. Outcomes before term should be analyzed with care, using methods that address bias due to selection of preterm deliveries.

Improving surveillance for the hidden half of fetal-infant mortality: a pilot study of the expansion of the Pregnancy Risk Assessment Monitoring System to include stillbirth

PurposeIn the United States, stillbirths (fetal deaths ≥ 20 weeks' gestation) are now more common than infant deaths. Nationally available data are limited, and little is known about women's experiences around the time of a loss. The Pregnancy Risk Assessment Monitoring System (PRAMS), a state-based survey of women with a recent live birth, could be expanded to include women who experienced a stillbirth. We aimed to determine whether women with a recent stillbirth would be amenable to a PRAMS-like survey. MethodsEligible women were Georgia residents aged ≥18 years with a reported stillbirth from December 1, 2012–February 28, 2013 identified through fetal death certificates. Women received a handwritten sympathy card, followed by a mailed questionnaire about their health and experiences around the time of the loss. Nonresponders received two additional mailings and up to three phone calls. ResultsDuring the study period, 149 eligible women had a reported stillbirth. Forty-nine (33%) women responded. Excluding women with invalid contact information (n = 26) yields an adjusted response rate of 40%. Response differed by race and/or ethnicity, but not by fetal, delivery, or other maternal characteristics. ConclusionsWomen appear willing to respond to a survey regarding a recent stillbirth. Further studies of the expansion of PRAMS to include stillbirth are warranted.

Thinking outside the curve, part II: modeling fetal-infant mortality.

BackgroundGreater epidemiologic understanding of the relationships among fetal-infant mortality and its prognostic factors, including birthweight, could have vast public health implications. A key step toward that understanding is a realistic and tractable framework for analyzing birthweight distributions and fetal-infant mortality. The present paper is the second of a two-part series that introduces such a framework.MethodsWe propose estimating birthweight-specific mortality within each component of a normal mixture model representing a birthweight distribution, the number of components having been determined from the data rather than fixed a priori.ResultsWe address a number of methodological issues related to our proposal, including the construction of confidence intervals for mortality risk at any given birthweight within a component, for odds ratios comparing mortality within two different components from the same population, and for odds ratios comparing mortality within analogous components from two different populations. As an illustration we find that, for a population of white singleton infants, the odds of mortality at 3000 g are an estimated 4.15 times as large in component 2 of a 4-component normal mixture model as in component 4 (95% confidence interval, 2.04 to 8.43). We also outline an extension of our framework through which covariates could be probabilistically related to mixture components. This extension might allow the assertion of approximate correspondences between mixture components and identifiable subpopulations.ConclusionsThe framework developed in this paper does not require infants from compromised pregnancies to share a common birthweight-specific mortality curve, much less assume the existence of an interval of birthweights over which all infants have the same curve. Hence, the present framework can reveal heterogeneity in mortality that is undetectable via a contaminated normal model or a 2-component normal mixture model.

Thinking outside the curve, part I: modeling birthweight distribution.

BackgroundGreater epidemiologic understanding of the relationships among fetal-infant mortality and its prognostic factors, including birthweight, could have vast public health implications. A key step toward that understanding is a realistic and tractable framework for analyzing birthweight distributions and fetal-infant mortality. The present paper is the first of a two-part series that introduces such a framework.MethodsWe propose describing a birthweight distribution via a normal mixture model in which the number of components is determined from the data using a model selection criterion rather than fixed a priori.ResultsWe address a number of methodological issues, including how the number of components selected depends on the sample size, how the choice of model selection criterion influences the results, and how estimates of mixture model parameters based on multiple samples from the same population can be combined to produce confidence intervals. As an illustration, we find that a 4-component normal mixture model reasonably describes the birthweight distribution for a population of white singleton infants born to heavily smoking mothers. We also compare this 4-component normal mixture model to two competitors from the existing literature: a contaminated normal model and a 2-component normal mixture model. In a second illustration, we discover that a 6-component normal mixture model may be more appropriate than a 4-component normal mixture model for a general population of black singletons.ConclusionsThe framework developed in this paper avoids assuming the existence of an interval of birthweights over which there are no compromised pregnancies and does not constrain birthweights within compromised pregnancies to be normally distributed. Thus, the present framework can reveal heterogeneity in birthweight that is undetectable via a contaminated normal model or a 2-component normal mixture model.

Assessing Maternal Risk for Fetal-Infant Mortality: A Population-Based Study to Prioritize Risk Reduction in a Healthy Start Community

Study goals were to distinguish between maternal risk factors for fetal versus infant mortality, and to identify which maternal characteristics contributed the greatest risk of mortality overall. This case-control retrospective study abstracted data on more than forty maternal characteristics from 261 prenatal and delivery records: all 26 fetal deaths, all 40 infant deaths and 195 randomly selected surviving births in a high-mortality Healthy Start community. Bivariate and multivariate analyses were conducted. The fetal-mortality population was significantly more likely than the infant-mortality population to have no insurance (P = .047), inadequate prenatal care (P = .039) and previous fetal death (P = .021). Comparing the combined mortality population with the surviving sample, two tiers of risk emerged: Rare-but-lethal risks, including no prenatal care (P < .001) and Child-Protective-Service involvement (P = .001), and common-and-dangerous risks, including inadequate maternal weight gain (OR = 13.55), drug or alcohol abuse (OR = 8.67), obesity (OR = 2.77) and anemia (OR = 3.61). Both fetal and infant mortality groups must be considered when identifying maternal risks. Inadequate prenatal weight gain, obesity and anemia contribute as much to feto-infant mortality as substance abuse. Public health efforts to improve maternal nutrition and healthy weight should be redoubled.

Excess Hispanic fetal-infant mortality in a midwestern community.

We assessed excess fetal-infant mortality for Hispanic, non-Hispanic white, and non-Hispanic black populations in five contiguous counties of Missouri and Kansas. We conducted a perinatal periods of risk (PPOR) assessment of fetal-infant mortality using electronic linked birth-death record files from 2001 through 2005. We generated an internal reference group in accordance with established PPOR protocol. We used Kitagawa analysis to determine whether excess deaths were due to birthweight distribution (a higher frequency of prematurity or growth retardation) or to higher mortality rates once born at that birthweight (birthweight-specific mortality). We found the excess fetal-infant death rates for Hispanic and non-Hispanic white populations to be similar and considerably lower than that for non-Hispanic black populations. Among Hispanic children, we judged 21.6% of fetal-infant mortality to be excess in relation to the reference population. Within the PPOR matrix, Hispanic excess mortality rates were distributed differently from those of non-Hispanic white and non-Hispanic black populations. Among Hispanic children, 93.6% of the excess mortality could be explained by low birthweight and birthweight-specific mortality, with the greatest contribution attributable to low birthweight. The excess fetal-infant mortality experience of Hispanic people in the five-county region was similar to that of the non-Hispanic white population, but was distributed differently in the PPOR model, which has significance regarding interventions targeting reductions in fetal-infant mortality.

Reducing Infant Mortality Rates Using the Perinatal Periods of Risk Model

Despite decreases in the last 50 years, infant mortality rates in the United States remain higher than in other industrialized countries. Using overall infant mortality rates to determine the effectiveness of interventions does not help communities focus on particular underlying factors contributing to static, and sometimes increasing, community rates. This study was designed to determine and rank contributing factors to fetal-infant mortality in a specific community using the Perinatal Periods of Risk (PPOR) model. The PPOR model was used to map fetal-infant mortality for 1995 to 1998 in the Tulsa, Oklahoma, Healthy Start Program as compared to traditional calculation methods. The overall fetal-infant mortality rate using the PPOR model was 12.7 compared to 7.11 calculated using the traditional method. The maternal health cell rate was 5.4, maternal care cell rate was 2.9, newborn care cell was 1.9 compared to a 4.1 neonatal death rate calculated using the traditional method, and the infant health cell was 2.4 compared to a 2.9 postneonatal rate calculated using the traditional method. Because the highest infant mortality was in the maternal health cell, intervention strategies were designed to promote the health of women prior to and between pregnancies. The PPOR model was helpful in targeting interventions to reduce fetal-infant mortality based on the prioritization of contributing factors.

La mortalité infantile en Europe et au Canada : un problème résolu?

"Tendencies in foetal-infant mortality in countries characterized by very low overall mortality rates should be set forth in terms of health. First with respect to physical health, greater use of technology in reproductive matters is translated by an increase in both survival rates of very low birth weight infants and, in certain countries, in multiple deliveries. Next concerning social health, given the persistence and potential deepening of social inequalities, it is unlikely that overall rates have reached a peak. Several indicators can be developed with vital statistics, including incidence of low and very low birth weight, specific risks by birth weight, and differential risks by social characteristics of the parents. These phenomena can be monitored and, to a certain extent, compared in [Canada and] a large number of European countries." (SUMMARY IN ENG AND SPA)

Changes in the registration of stillbirths < 500 g in Canada, 1985-95. Fetal-Infant Mortality Study Group of the Canadian Perinatal Surveillance System.

We assessed recent temporal trends in the registration of stillbirths in Canada, with particular regard to stillbirths < 500 g. Data from the Statistics Canada live birth and stillbirth databases for the period 1985-95 were used for the study. The primary analysis was restricted to data from 10 of the 12 provinces and territories of Canada. Data from Newfoundland were excluded because birthweight distributions were not available prior to 1990, and data from Ontario were excluded because of concerns about data quality. The proportion of stillbirths < 500 g increased by 47% [95% confidence interval (CI) 32, 63%], from 12.7% of stillbirths with known birthweight in 1985-7 to 18.7% in 1993-5. Similarly, the rate of stillbirths < 500 g increased by 36% [95% CI 21, 53%], from 7.2 to 9.8 per 10,000 total births from 1985-7 to 1993-5. Similar increases in stillbirth rates were not observed in other low birthweight categories. Live births < 500 g increased 53% [95% CI 33, 77%], from 4.6 to 7.0 per 10,000 live births. Some provinces and territories had low rates of stillbirths < 500 g and no increasing trend, whereas other provinces showed higher rates and increases over time. These regional differences were consistent with differences in stillbirth definitions across the provinces and territories of Canada. Spatio-temporal comparisons of crude stillbirth rates are likely to be compromised unless differences and changes in birth registration practices are addressed.

The impact of extreme prematurity and congenital anomalies on the interpretation of international comparisons of infant mortality

To identify the potential impact that different definitions of live births and practice patterns have on infant mortality rates in England and Wales, France, Japan, and the United States. United States data were obtained from the 1986 linked national birth-infant death cohort, and those for the other countries came from either published sources or directly from the Ministries of Health. In 1986 in the United States, infants weighing less than 1 kg accounted for 36% of deaths (32% white and 46% black); 32% resulted from fatal congenital anomalies. These rates were much higher in both categories than in England and Wales in 1990 (24 and 22%, respectively), France in 1990 (15 and 25%, respectively), and Japan in 1991 (9% for infants weighing less than 1 kg, percentage of fatal congenital anomalies unknown). These cases are more likely to be excluded from infant mortality statistics in their countries than in the United States. In 1990, the United States infant mortality rate was 9.2 per 1000 live births, ranking the United States 19th internationally. However, infant mortality provides a poor comparative measure of reproductive outcome because there are enormous regional and international differences in clinical practices and in the way live births are classified. Future international and state comparisons of reproductive health should standardize the definition of a live birth and fatal congenital anomaly, and use weight-specific fetal-infant mortality ratios and perinatal statistics.