Changes in the distribution of maternal age and parity and increasing trends in the low birth weight rate in Korea between 1995 and 2005

Objectives

This study measured the impact of shifts in maternal age and parity on the increase in the low birth weight (LBW) rate in Korea.

Methods

We obtained raw data for all 6 397 945 live births registered at the Korea National Statistical Office between 1995 and 2005. We calculated the proportion of increment in the LBW rate due to changes in the distribution of maternal age and parity (AP-dis) and the proportion due to changes in the age- and parity-specific LBW rate (AP-spe).

Results

The LBW rate increased from 3.02% in 1995 to 4.28% in 2005. The multiple birth rate increased from 1.32% to 2.19% during the same period. Of the 1.26% points increment in the LBW rate, 0.64% points occurred among singleton births and 0.62% points occurred among multiple births. Changes in the AP-dis accounted for 50% of the increase in the LBW rate among singleton births, but did not contribute to the increase in the LBW rate among multiple births. The remainder of the total increment in the LBW rate was explained by the increase in the AP-spe.

Conclusions

This study demonstrated that shifts in maternal age and parity among singleton births and increased multiple births were important contributors to the increment in the LBW rate. This study also revealed that the increase in the AP-spe was an equally important contributor as the shifts in maternal age and parity to the increment in the LBW rate among singleton births and was a major contributor among multiple births.     

Community-based surveillance of maternal deaths in rural Ghana

Objective

To examine the feasibility and effectiveness of community-based maternal mortality surveillance in rural Ghana, where most information on maternal deaths usually comes from retrospective surveys and hospital records.

Methods

In 2013, community-based surveillance volunteers used a modified reproductive age mortality survey (RAMOS 4+2) to interview family members of women of reproductive age (13–49 years) who died in Bosomtwe district in the previous five years. The survey comprised four yes–no questions and two supplementary questions. Verbal autopsies were done if there was a positive answer to at least one yes–no question. A mortality review committee established the cause of death.

Findings

Survey results were available for 357 women of reproductive age who died in the district. A positive response to at least one yes–no question was recorded for respondents reporting on the deaths of 132 women. These women had either a maternal death or died within one year of termination of pregnancy. Review of 108 available verbal autopsies found that 64 women had a maternal or late maternal death and 36 died of causes unrelated to childbearing. The most common causes of death were haemorrhage (15) and abortion (14). The resulting maternal mortality ratio was 357 per 100 000 live births, compared with 128 per 100 000 live births derived from hospital records.

Conclusion

The community-based mortality survey was effective for ascertaining maternal deaths and identified many deaths not included in hospital records. National surveys could provide the information needed to end preventable maternal mortality by 2030.     

The Japan Environment and Children’s Study (JECS): A Preliminary Report on Selected Characteristics of Approximately 10 000 Pregnant Women Recruited During the First Year of the Study

Background

The Japan Environment and Children’s Study (JECS) is an ongoing nationwide birth cohort study launched in January 2011. In this progress report, we present data collected in the first year to summarize selected maternal and infant characteristics.

Methods

In the 15 Regional Centers located throughout Japan, the expectant mothers were recruited in early pregnancy at obstetric facilities and/or at local government offices issuing pregnancy journals. Self-administered questionnaires were distributed to the women during their first trimester and then again during the second or third trimester to obtain information on demographic factors, physical and mental health, lifestyle, occupation, environmental exposure, dwelling conditions, and socioeconomic status. Information was obtained from medical records in the first trimester and after delivery on medical history, including gravidity and related complications, parity, maternal anthropometry, and infant physical examinations.

Results

We collected data on a total of 9819 expectant mothers (mean age = 31.0 years) who gave birth during 2011. There were 9635 live births. The selected infant characteristics (singleton births, gestational age at birth, sex, birth weight) in the JECS population were similar to those in national survey data on the Japanese general population.

Conclusions

Our final birth data will eventually be used to evaluate the national representativeness of the JECS population. We hope the JECS will provide valuable information on the impact of the environment in which our children live on their health and development.Key words: birth cohort, pregnant women, children, environmental chemicals, Japan     

Distribution of birth weight for gestational age in Japanese infants delivered by cesarean section

Background

Neonatal anthropometric charts of the distribution of measurements, mainly birth weight, taken at different gestational ages are widely used by obstetricians and pediatricians. However, the relationship between delivery mode and neonatal anthropometric data has not been investigated in Japan or other countries.

Methods

The subjects were selected from the registration database of the Japan Society of Obstetrics and Gynecology (2003–2005). Tenth centile, median, and 90th centile of birth weight by sex, birth order, and delivery mode were observed by gestational age from 22 to 42 weeks among eligible singleton births.

Results

After excluding 248 outliers and 5243 births that did not satisfy the inclusion criteria, 144 980 births were included in the analysis. The distribution of 10th centile curves was skewed toward lower birth weights during the preterm period among both first live births and second and later live births delivered by cesarean section. More than 40% of both male and female live births were delivered by cesarean section at 37 weeks or earlier.

Conclusions

The large proportion of cesarean sections influenced the skewness of the birth weight distribution in the preterm period.Key words: birth weight, distribution, gestational age, cesarean section, preterm     

Correcting vital information: estimating infant mortality,Brazil, 2000-2009

OBJECTIVE

To propose a simplified method of correcting vital information and estimating the coefficient of infant mortality in Brazil.

METHODS

Vital data in the information systems on mortality and live births were corrected using correction factors, estimated based on events not reported to the Brazilian Ministry of Health and obtained by active search. This simplified method for correcting vital information for the period 2000-2009 for Brazil and its federal units establishes the level of adequacy of information on deaths and live births by calculating the overall coefficient of mortality standardized by age and the ratio between reported and expected live births, respectively, in each Brazilian municipality. By applying correction factors to the number of deaths and live births reported in each county, the vital statistics were corrected, making it possible to estimate the coefficient of infant mortality.

RESULTS

The highest correction factors were related to infant deaths, reaching values higher than 7 for municipalities with very precarious mortality information. For deaths and live births, the correction factors exhibit a decreasing gradient as indicators of adequacy of the vital information improve. For the year 2008, the vital information corrected by the simplified method per state were similar to those obtained in the research of active search. Both the birth rate and the infant mortality rate decreased in the period in all Brazilian regions. In the Northeast, the annual rate of decline was 6.0%, the highest in Brazil (4.7%).

CONCLUSIONS

The active search of deaths and births allowed correction factors to be calculated by level of adequacy of mortality information and live births. The simplified method proposed here allowed vital information to be corrected per state for the period 2000-2009 and the progress of the coefficient of infant mortality in Brazil, its regions and states to be assessed.     

Rural-urban differentials in pregnancy-related mortality in Zambia: estimates using data collected in a census

Background

The use of census data to measure maternal mortality is a recent phenomenon, implemented in settings with non-functional vital registration systems and driven by needs for trend data. The 2010 round of population and housing censuses recorded a significant increase in the number of countries collecting maternal mortality data. The objective of this study was to estimate rural-urban differentials in pregnancy-related mortality in Zambia using census data.

Methods

We used data from the Zambia 2000 and 2010 censuses. Both censuses recorded the female population by age, the number of children ever born, and live births 12 months prior to the census. The 2010 census further recorded, by age, household, and pregnancy-related deaths 12 months prior to the census. We evaluated and adjusted recorded live births using the cohort Parity Fertility ratio method, and household deaths using deaths distribution methods (General Growth Balance and Synthetic Extinct Generation). Adult female mortality and pregnancy-related mortality for rural and urban areas were estimated for the period October 2009 to October 2010.

Results

Data evaluation showed errors in recorded population age, age-at-death, live births, and deaths, and appropriate adjustments were made. Adjusted adult female mortality was high; an adolescent aged 15 years had a one-in-three chance of dying before her 50th birthday in rural areas and one-in-four chance in urban areas. Pregnancy-related deaths comprised 15.3 % of all deaths among reproductive-age women overall; 17.9 % in rural areas and 9.8 % in urban areas. The pregnancy-related mortality ratio for the period was 789 deaths/100,000 live births overall: 960/100,000 live births in rural areas and 470/100,000 live births in urban areas.

Conclusions

Census-based estimates show very high adult female mortality and particularly high pregnancy-related mortality in both rural and urban areas of Zambia 12 months prior to the 2010 census. Future censuses should pay greater attention to strategies for improving data quality.

     

The Effect of an Increase in the Rate of Multiple Births on Low-Birth-Weight and Preterm Deliveries during 1975–2008

Background

Despite the rapid increase in the rate of multiple births due to the growth of reproductive medicine, there have been no epidemiologic studies of the secular trends in the impact of multiple births on the rates of low-birth-weight and preterm deliveries in Japan.

Methods

Japanese vital statistics for multiple live births were obtained from the Ministry of Health, Labour and Welfare and reanalyzed. With singletons as the reference group, an analysis was performed of secular trends in relative risk and population attributable risk percent of low-birth-weight (<2500 grams), very-low-birth-weight (<1500 grams), and extremely-low-birth-weight (<1000 grams) deliveries, using 1975–2008 vital statistics, and of preterm deliveries (ie, before 37, 32, and 28 weeks), using 1979–2008 vital statistics.

Results

The rate of multiple births doubled during the past 2 decades, and about 2% of all neonates are now multiples. The population attributable risk percent tended to increase during the same period for all variables, and was approximately 20% in 2008.

Conclusions

The public health impact of the rapid increase in multiple births remains high in Japan.Key words: multiple births, low birth weight, preterm delivery, relative risk, population attributable risk percent     

Birth Weight among Singletons Born to Foreign-Born Mothers in Taiwan: A Population-Based Birth Register Study

Background

We compared the birth weight of newborns born to foreign-born mothers (FBMs) and Taiwan-born mothers (TBMs), using data from the 2005–2006 Taiwan Birth Registry of singleton live births.

Methods

The Wilcox–Russell method, data restriction, and multiple linear regression were used to analyze the data. The rates of low birth weight (<2500 g) with 95% confidence intervals were computed for TBMs, and for each of the nationalities of FBMs.

Results

The mean birth weight of newborns of FBMs was 3157 g, which was higher than that of newborns of TBMs (3109 g). On analysis using the Wilcox–Russell method, both the rate and residual proportion of low-birth-weight (LBW) births were lower among newborns of FBMs (4.1% and 1.1%, respectively) than among newborns of TBMs (5.9% and 1.7%, respectively). After adjusting for sex, mode of delivery, maternal age, smoking status, predisposing maternal risk factors, and condition during pregnancy, the newborns of FBMs weighed 72.9 g (95% CI, 68.8 g to 77.0 g) more than the newborns of TBMs. When data were restricted to mothers without any adverse conditions and adjusted for maternal age, the differences in birth weight between the 2 groups remained unchanged. The rates of LBW deliveries among FBMs in Taiwan were significantly lower than those in their respective countries of origin.

Conclusions

In Taiwan, newborns of FBMs had a higher birth weight than those of TBMs, even after accounting for potential confounding factors, and had lower rates of LBW deliveries than did mothers in their respective countries of origin.Key words: birth weight, transnational marriage, foreign-born mothers     

Estimating pregnancy-related mortality from census data: experience in Latin America

Objective

To assess the feasibility of measuring maternal mortality in countries lacking accurate birth and death registration through national population censuses by a detailed evaluation of such data for three Latin American countries.

Methods

We used established demographic techniques, including the general growth balance method, to evaluate the completeness and coverage of the household death data obtained through population censuses. We also compared parity to cumulative fertility data to evaluate the coverage of recent household births. After evaluating the data and adjusting it as necessary, we calculated pregnancy-related mortality ratios (PRMRs) per 100 000 live births and used them to estimate maternal mortality.

Findings

The PRMRs for Honduras (2001), Nicaragua (2005) and Paraguay (2002) were 168, 95 and 178 per 100 000 live births, respectively. Surprisingly, evaluation of the data for Nicaragua and Paraguay showed overreporting of adult deaths, so a downward adjustment of 20% to 30% was required. In Honduras, the number of adult female deaths required substantial upward adjustment. The number of live births needed minimal adjustment. The adjusted PRMR estimates are broadly consistent with existing estimates of maternal mortality from various data sources, though the comparison varies by source.

Conclusion

Census data can be used to measure pregnancy-related mortality as a proxy for maternal mortality in countries with poor death registration. However, because our data were obtained from countries with reasonably good statistical systems and literate populations, we cannot be certain the methods employed in the study will be equally useful in more challenging environments. Our data evaluation and adjustment methods worked, but with considerable uncertainty. Ways of quantifying this uncertainty are needed.     

Is the Prevalence of Down Syndrome Births in Hawai‘i Increasing?

Purpose

In response to a study published by the Centers for Disease Control and Prevention (CDC) in 2009, which indicated that the prevalence of Down syndrome births was increasing in the 10 regions studied, this study examined whether a similar trend was occurring in Hawai‘i.

Methods

Data were obtained from the Hawai‘i State Department of : Health Birth Defects Program for the years 1997–2005. The information was analyzed by numbers of live births and outcomes of Down syndrome pregnancies, by ratio of terminations to live births, by age of mother (< 35 years or ≥ 35 years), by maternal ethnicity, and by whether the baby was born with a congenital heart defect (a frequent concomitant condition of babies born with Down Syndrome). These results were compared with previously published studies on the prevalence of Down syndrome births and pregnancies in Hawai‘i and were also compared with recently published data of the CDC.

Findings

The study found that the prevalence of Down syndrome : births for Hawai‘i over the nine-year period did not change significantly. Thus, this finding did not match the findings of the CDC study. Additionally, the data showed that the prevalence of congenital heart defects was higher in Hawai‘i than in other areas. However, because of changes in the resources available to the Hawai‘i Birth Defects Program, fully comparing in all respects data from the 1997–2005 period with studies conducted earlier in Hawai‘i was not possible.

Conclusions

The data identified a number of areas in need of further : study. These areas include the following: 1) an examination of the kinds of information and counseling given by primary care providers to women following a prenatal diagnosis of Down syndrome; 2) analysis of the characteristics, values, and choices made by these women to terminate the pregnancy or continue it to term; and 3) determination of why the prevalence of congenital heart defects appears higher among births of babies with Down syndrome in Hawai‘i than elsewhere.     

Prenatal exposure to perfluorooctanoate (PFOA) and perfluorooctanesulfonate (PFOS) and maternally reported developmental milestones in infancy

Background

Perfluorooctanesulfonate (PFOS) and perfluorooctanoate (PFOA) are fluorinated organic compounds present in the general population at low concentrations. Animal studies have shown that they may affect neuromuscular development at high concentrations.

Objectives

We investigated the association between plasma levels of PFOS and PFOA in pregnant women and motor and mental developmental milestones of their children.

Methods

We randomly selected 1,400 pairs of pregnant women and their children from the Danish National Birth Cohort. PFOS and PFOA were measured in maternal blood samples taken in early pregnancy. Apgar score was abstracted from the National Hospital Discharge Register in Denmark. Developmental milestones were reported by mothers using highly structured questionnaires when the children were around 6 months and 18 months of age.

Results

Mothers who had higher levels of PFOA and PFOS gave birth to children who had similar Apgar scores and reached virtually all of the development milestones at the same time as children born to mothers with lower exposure levels. Children who were born to mothers with higher PFOS levels were slightly more likely to start sitting without support at a later age.

Conclusion

We found no convincing associations between developmental milestones in early childhood and levels of PFOA or PFOS as measured in maternal plasma early in pregnancy.     

Maternal Exposure to a Brominated Flame Retardant and Genitourinary Conditions in Male Offspring

Background

The upward trend in industrial nations in the incidence of male genitourinary (GU) conditions may be attributed to increased exposure to endocrine disruptors. Polybrominated biphenyl (PBB), a brominated flame retardant, is one such suspected endocrine disruptor.

Objective

We investigated the relationship between maternal serum levels of PBBs and GU conditions among male offspring exposed in utero.

Methods

In this cohort study of sons born to women accidentally exposed to PBBs during 1973–1974, we examined self-reported data on GU conditions among male offspring in relation to maternal serum PBB levels. We used generalized estimating equations to calculate odds ratios (ORs), controlling for gestational age at birth.

Results

Of 464 sons, 33 reported any GU condition (13 hernias, 10 hydroceles, 9 cryptorchidism, 5 hypospadias, and 1 varicocele). Four reported both hernia and hydrocele, and one both hernia and cryptorchidism. After adjustment for gestational age at birth, sons of highly exposed women (> 5 ppb) were twice as likely to report any GU condition compared with sons of the least exposed women [≤1 ppb; OR = 2.0; 95% confidence interval (CI), 0.8–5.1]. This risk was increased when we excluded sons born after the exposure but before the mother’s serum PBB measurement (OR = 3.1; 95% CI, 1.0–9.1). We found evidence of a 3-fold increase in reported hernia or hydrocele among sons with higher PBB exposure (test of trend p-value = 0.04). Neither hypospadias nor cryptorchidism was individually associated with PBB exposure.

Conclusions

Although cryptorchidism and hypospadias were not associated with in utero PBB exposure, this study suggests that other GU conditions may be associated with exposure to endocrine-disrupting chemicals during development.     

Mendelian Randomization Analysis of the Effect of Maternal Homocysteine During Pregnancy,as Represented by Maternal MTHFR C677T Genotype,on Birth Weight

Background

We used Mendelian randomization analysis to investigate the causal relationship between maternal homocysteine level, as represented by maternal methylenetetrahydrofolate reductase (MTHFR) C677T genotype, with the birth weight of offspring.

Methods

We recruited women at 24 to 28 weeks’ gestation who visited Ewha Womans University Hospital for prenatal care during the period from August 2001 to December 2003. A total of 473 newborns with a gestational age of at least 37 weeks were analyzed in this study. We excluded twin births and children of women with a history of gestational diabetes, gestational hypertension, or chronic renal disease. The association of maternal homocysteine concentration with the birth weight of infants was analyzed using 2-stage regression.

Results

MTHFR C677T genotype showed a dose–response association with homocysteine concentration for each additional T allele (P_trend < 0.01). Birth weight decreased from 120 to 130 grams as maternal homocysteine level increased, while controlling for confounding factors; however, the association was of marginal significance (P = 0.06).

Conclusions

Our results suggest an adverse relationship between maternal homocysteine level and birth weight. A reduction in homocysteine levels might positively affect birth outcomes.Key words: birth weight, homocysteine, intrauterine environment, Mendelian randomization, methylenetetrahydrofolate reductase     

Maternal mortality estimation at the subnational level: a model-based method with an application to Bangladesh

Objective

To provide a model-based method of estimating maternal mortality at the subnational level and illustrate its use in estimating maternal mortality rates (MMrates) and maternal mortality ratios (MMRs) in all 64 districts of Bangladesh.

Methods

Knowing that mortality is more pronounced among the poorer segments of a population, in rural areas and in areas with poor availability and utilization of maternal care, we used an empirical Bayesian prediction method to estimate maternal mortality at the subnational level from the spatial distribution of such factors.

Findings

MMRs varied significantly by district in Bangladesh, from 158 maternal deaths per 100 000 live births at Dhaka district to 782 in the northern coastal regions. Maternal mortality was consistently higher in the eastern and northern regions, which are known to be culturally conservative and to have poor transportation systems.

Conclusion

Bangladesh has made noteworthy strides in reducing maternal mortality since 1990, even though the utilization of skilled birth attendants has increased very little. However, several areas still show alarmingly high maternal mortality figures and need to be prioritized and targeted by health administrators and policy-makers.     

Time trends and regional differences in maternal mortality in China from 2000 to 2005

Objective

To examine trends and variations in maternal mortality in China between 2000 and 2005.

Methods

We used Poisson regression analysis of data from the Chinese National Maternal and Child Health Routine Reporting System between 2000 and 2005 to identify time trends in the maternal mortality ratio (MMR) by province and region.

Findings

The MMR declined by an average of 5% per year (crude relative risk, RR: 0.95; 95% confidence interval, CI: 0.94–0.97). There was no interaction between region and year (P = 0.2311). Mortality declined by 5% per year in the eastern region (crude RR: 0.95; 95% CI: 0.92–0.97), by 5% per year in the central region (crude RR; 0.95; 95% CI: 0.94–0.96), and by 4% per year in the western region (crude RR: 0.96; 95% CI: 0.94–0.98). The absolute difference in MMR between the western and eastern regions declined from 65.4 deaths per 100 000 live births in 2000 to 49.4 per 100 000 live births in 2005.

Conclusion

China is making good progress towards achieving the fifth Millennium Development Goal, and there is no evidence of a widening gap between better-off and economically more deprived provinces.     

Estimation of maternal and child mortality one year after user-fee elimination: an impact evaluation and modelling study in Burkina Faso

Objective

To estimate the impact on maternal and child mortality after eliminating user fees for pregnant women and for children less than five years of age in Burkina Faso.

Methods

Two health districts in the Sahel region eliminated user fees for facility deliveries and curative consultations for children in September 2008. To compare health-care coverage before and after this change, we used interrupted time series, propensity scores and three independent data sources. Coverage changes were assessed for four variables: women giving birth at a health facility, and children aged 1 to 59 months receiving oral rehydration salts for diarrhoea, antibiotics for pneumonia and artemesinin for malaria. We modelled the mortality impact of coverage changes in the Lives Saved Tool using several scenarios.

Findings

Coverage increased for all variables, however, the increase was not statistically significant for antibiotics for pneumonia. For estimated mortality impact, the intervention saved approximately 593 (estimate range 168–1060) children’s lives in both districts during the first year. This lowered the estimated under-five mortality rate from 235 deaths per 1000 live births in 2008 to 210 (estimate range 189–228) in 2009. If a similar intervention were to be introduced nationwide, 14 000 to 19 000 (estimate range 4000–28 000) children''s lives could be saved annually. Maternal mortality showed a modest decrease in all scenarios.

Conclusion

In this setting, eliminating user fees increased use of health services and may have contributed to reduced child mortality.     

Population Physiologically Based Pharmacokinetic Modeling for the Human Lactational Transfer of PCB-153 with Consideration of Worldwide Human Biomonitoring Results

Background

One of the most serious human health concerns related to environmental contamination with polychlorinated biphenyls (PCBs) is the presence of these chemicals in breast milk.

Objectives

We developed a physiologically based pharmacokinetic model of PCB-153 in women, and predict its transfer via lactation to infants. The model is the first human, population-scale lactational model for PCB-153. Data in the literature provided estimates for model development and for performance assessment.

Methods

We used physiologic parameters from a cohort in Taiwan and reference values given in the literature to estimate partition coefficients based on chemical structure and the lipid content in various body tissues. Using exposure data from Japan, we predicted acquired body burden of PCB-153 at an average childbearing age of 25 years and compared predictions to measurements from studies in multiple countries. We attempted one example of reverse dosimetry modeling using our PBPK model for possible exposure scenarios in Canadian Inuits, the population with the highest breast milk PCB-153 level in the world.

Results

Forward-model predictions agree well with human biomonitoring measurements, as represented by summary statistics and uncertainty estimates.

Conclusion

The model successfully describes the range of possible PCB-153 dispositions in maternal milk, suggesting a promising option for back-estimating doses for various populations.     

Maternal exposure to ambient levels of benzene and neural tube defects among offspring: Texas, 1999-2004

Background

Previous studies have reported positive associations between maternal exposure to air pollutants and several adverse birth outcomes. However, there have been no studies assessing the association between environmental levels of hazardous air pollutants, such as benzene, and neural tube defects (NTDs), a common and serious group of congenital malformations.

Objective

Our goal was to conduct a case–control study assessing the association between ambient air levels of benzene, toluene, ethylbenzene, and xylene (BTEX) and the prevalence of NTDs among offspring.

Methods

The Texas Birth Defects Registry provided data on NTD cases (spina bifida and anencephaly) delivered between 1999 and 2004. The control group was a random sample of unaffected live births, frequency matched to cases on year of birth. Census tract–level estimates of annual BTEX levels were obtained from the U.S. Environmental Protection Agency 1999 Assessment System for Population Exposure Nationwide. Restricted cubic splines were used in mixed-effects logistic regression models to determine associations between each pollutant and NTD phenotype.

Results

Mothers living in census tracts with the highest benzene levels were more likely to have offspring with spina bifida than were women living in census tracts with the lowest levels (odds ratio = 2.30; 95% confidence interval, 1.22–4.33). No significant associations were observed between anencephaly and benzene or between any of the NTD phenotypes and toluene, ethylbenzene, or xylene.

Conclusion

In the first study to assess the relationship between environmental levels of BTEX and NTDs, we found an association between benzene and spina bifida. Our results contribute to the growing body of evidence regarding air pollutant exposure and adverse birth outcomes.     

Perfluorinated chemicals and fetal growth: a study within the Danish National Birth Cohort

Background

Perfluorooctanesulfonate (PFOS) and perfluorooctanoate (PFOA) are man-made, persistent organic pollutants widely spread throughout the environment and human populations. They have been found to interfere with fetal growth in some animal models, but whether a similar effect is seen in humans is uncertain.

Objectives

We investigated the association between plasma levels of PFOS and PFOA in pregnant women and their infants’ birth weight and length of gestation.

Methods

We randomly selected 1,400 women and their infants from the Danish National Birth Cohort among those who completed all four computer-assisted telephone interviews, provided the first blood samples between gestational weeks 4 and 14, and who gave birth to a single live-born child without congenital malformation. PFOS and PFOA were measured by high performance liquid chromatography–tandem mass spectrometer.

Results

PFOS and PFOA levels in maternal plasma were on average 35.3 and 5.6 ng/mL, respectively. Only PFOA levels were inversely associated with birth weight (adjusted β = −10.63 g; 95% confidence interval, −20.79 to −0.47 g). Neither maternal PFOS nor PFOA levels were consistently associated with the risk for preterm birth or low birth weight. We observed no adverse effects for maternal PFOS or PFOA levels on small for gestational age.

Conclusion

Our nationwide cohort data suggest an inverse association between maternal plasma PFOA levels and birth weight. Because of widespread exposure to these chemicals, our findings may be of potential public health concern.