Maternal and cord blood manganese (Mn) levels and birth weight: The MIREC birth cohort study

Epidemiological studies have hypothesized that both insufficient and excess blood manganese (Mn) levels during pregnancy are associated with reduced fetal growth. This literature is characterized by inconsistent results and a limited focus on women with exposures representative of the general North American population. We examined the relationship between maternal and cord blood Mn levels and fetal growth among women enrolled in the Maternal-Infant Research on Environmental Chemicals Study (MIREC). Mothers with singleton, term infants and complete maternal first and third trimester blood Mn data were eligible for inclusion in the present study (n?=?1519). Mean birth weight and odds ratios of small for gestational age (SGA) births according to maternal and cord blood Mn levels (low (<10), referent (10–<90), high (≥90) percentiles) were estimated. We also evaluated the association between the ratio of cord and maternal blood Mn and birth weight. Women with low (<0.82?μg/dL) maternal blood third trimester Mn levels had infants that weighed an average of 64.7?g (95% CI: ?142.3,12.8) less than infants born to women in the referent exposure group. This association was strengthened and became statistically significant when adjusted for toxic metals (lead, mercury, arsenic, and cadmium) [?83.3?g (95% CI: ?162.4, ?4.1)]. No statistically significant associations were observed in models of maternal first trimester or cord blood Mn. A one unit increase in the cord/maternal blood Mn ratio was associated with a 29.4?g (95% CI: ?50.2, ?8.7), when adjusted for maternal and neonatal characteristics. Our findings motivate additional research regarding the relation between Mn exposure and fetal growth. Further inquiry is necessary to determine whether an exposure threshold exists, how growth related effects of maternal and fetal Mn may differ, and how concurrent exposure to other toxic metals may impact the association between Mn and growth.     

The Spanish Environment and Childhood Research Network (INMA study)

Prenatal and early life exposure to environmental agents, including dietary exposure, is associated with child health and human development and predisposes to late adult effects. Children are more vulnerable than adults to chemical, physical and biological hazards in air, water and soil, because they are still growing and their immune system and detoxification mechanisms are not fully developed. The physical, social and intellectual development of children from conception to the end of adolescence requires a protected environment that is also protective of their health. Following WHO and European Union recommendations, the Cooperative Environment and Childhood Research Network was funded by the Spanish Ministry of Health to study effects of environment and diet on foetal and early childhood development in different geographical areas of Spain. This network integrates different multidisciplinary research groups and is comprised of six cohorts--three pre-existing and three de novo--which will prospectively follow up 3600 pregnant women from start of pregnancy until the children are 4-6-year old.     

Fear itself: The effects of distressing economic news on birth outcomes

I use new administrative data on mass layoffs and plant closings to study the effects of distressing economic news. Exposure to stressful events during pregnancy can impair fetal development. I find that announcement of impending job losses leads to a transient decrease in the mean birth weight within the firm's county one to four months before the job losses. A loss of 500 jobs corresponds roughly to a decrease of 15–20 g and 16 percent greater risk of low birth weight. Layoffs announced late in pregnancy are most strongly linked to decreased birth outcomes.     

孕期甲状腺激素敏感性与出生结局关系的队列研究

目的  研究孕期妇女甲状腺激素敏感性与出生结局的关系。方法  依托武汉市大型出生队列,以符合入选标准的5 411对孕妇-新生儿为研究对象。利用孕期体检的血清三碘甲状腺素(free triiodothyronine, FT3)、游离甲状腺素(free thyroxine, FT4)和甲状腺刺激激素(thyroid stimulating hormone, TSH),计算甲状腺激素中枢敏感性的指标：促甲状腺激素指数(thyroid stimulating hormone index, TSHI)、促甲状腺激素细胞-T4抵抗指数(thyrotroph thyroxine resistance index, TT4RI)和甲状腺反馈分位数指数(thyroid feedback quantile-based index, TFQI)。结局指标包括出生体重、出生孕周、出生体重Z评分,以及低出生体重、早产和小于胎龄儿(small for gestational age, SGA)。分别利用多元线性回归、logistic回归分析模型对甲状腺指标和出生结局中的连续型变量、分类变量进行回归分析,并控制可能混杂因素。结果  FT4、TSHI、TFQI与出生体重和出生体重Z评分呈负相关(均P≤0.01);甲状腺激素敏感性指标TSHI、TT4RI、TFQI与SGA存在统计学意义的正相关(TSHI: OR=1.52, 95% CI: 1.12~2.06, P＜0.01; TT4RI: OR=1.15, 95% CI: 1.03~1.29, P=0.02; TFQI: OR=1.41, 95% CI: 1.10~1.81, P＜0.01);甲状腺功能和甲状腺激素敏感性与低出生体重、早产的差异均无统计学意义。将妊娠合并甲状腺功能减退(甲减)人群排除后进行敏感性分析,研究结果一致。结论  孕期妇女甲状腺激素敏感性受损是不良出生结局SGA的独立风险因素。     

Mercury (Hg) and oxidative stress status in healthy mothers and its effect on birth anthropometric measures

This study was conducted to: (a) investigate the antagonistic interaction between selenium (Se) and mercury (Hg) in mothers and their newborns, (b) delineate the role of oxidative mechanisms induced by Hg exposure and (c) examine the protective effect of Se on Hg-induced oxidative stress and birth outcomes. Levels of Hg and Se were measured in umbilical cord blood and the placentas of 250 healthy mothers who participated in a study between 2006 and 2006 assessing prenatal exposure various pollutants. Levels of malondialdehyde (MDA) in cord and maternal blood and of 8-hydroxy-2-deoxyguanosine in urine were measured for assessing oxidative stress. Tail moment (TM) in the comet assay, as a biomarker of DNA damage was measured in samples of cord and maternal blood. The mean Se levels in umbilical cord blood (67.618 ± 12.897 μg/l) were lower than those reported in many countries, but none of the newborns had Se levels <20 μg/l (the threshold limit of Keshan disease). More than 80% of the newborns, though, had Se levels below the 80 μg/l needed for maximum glutathione peroxidase activity. Even though 18.6% of the newborns had levels of Hg ≥5.8 μg/l (the reference dose of the Environmental Protection Agency), no relationship was observed with the biomarkers of oxidative stress. The mean placental Hg levels (0.056 ± 0.075 μg/g dry wt.) were higher than those reported for newborns with abnormal fetal development. Our study also documented significant placental transfer of Hg and Se to the fetus. The Hg/Se molar ratio in both cord blood and placental tissue was well below 1. The average amount of Se in both matrices was approximately 50-fold in molar excess over Hg. The molar excess of Se in the umbilical cord (0.843 μmol/l), however, was lower than in placental tissues (13.098 μmol/kg dry wt.). In further support of the relationships of Hg and Se on oxidative stress, we observed significantly lower levels of maternal MDA associated with Se levels in both cord blood and placental tissues and significantly higher TM levels associated with placental Hg in both newborns and their mothers. In contrast, Se/Hg molar ratios in placental tissues were positively associated with MDA and negatively with TM. The disproportion between Hg and Se might be influenced by the length of Hg exposure that in turn might affect Se bioavailability. Each birth anthropometric outcome was modeled as a function of Hg, Se and their interactions. After an adjustment for confounding variables, Hg in cord blood had a significantly positive rather than the expected negative association with crown-heel length. Placental Hg was associated with reduced birth height. Both associations were independent of prematurity. The status of Se in newborns was positively associated with crown-heel length and placental weight, with and without preterm births, and with birth weight, but only without preterm births. In contrast, a lower cephalization index was correlated with Se levels in cord blood, which may be an indicator of a detrimental effect on health. Our study, however, revealed associations between significantly lower levels of placental Se and several birth anthropometric measures (head circumference, birth weight and birth height) but the significance disappeared after excluding preterm births. Regression analyses generally indicated either significant or marginally significant Hg–Se antagonistic interactions that may have moderated the toxic effect of Hg on head circumference and birth weight. This finding may be due to chance or residual confounding and so may not be clinically relevant, but it may also suggest that Hg, Se and Hg–Se interactions are important factors for understanding Hg-induced adverse birth outcomes. Additional research will be necessary to evaluate the biological impact of combined metals in the assessment of fetal growth and development.     

Maternal social capital and birth outcomes in the mother-child cohort in Crete, Greece (Rhea study)

This cohort study aimed to estimate the effect of individual maternal social capital during pregnancy on birth outcomes in the context of the Mother-child cohort (Rhea study), in Crete-Greece. Women were recruited from four prenatal clinics in Heraklion-Crete for one year beginning in February 2007. 610 women completed the self-administered Social Capital Questionnaire at about the 24th week of gestation. The scale assessed total maternal social capital and four social capital subscales: Participation in the Community, Feelings of Safety, Value of Life and Social Agency, and Tolerance of Diversity. Potential confounders included characteristics that have an established or potential association with the maternal social capital, and the birth outcomes (preterm birth, small weight for the gestational age, fetal weight growth restriction, weight, length and head circumference). The results of logistic and linear regression models indicated that there was an increase in the risk of preterm birth for every unit increase in maternal participation (range 12-48), and especially in the risk of medically indicated preterm birth. Although the findings suggest that participation is associated with an increased probability for preterm birth, we cannot know whether this is a protective or damaging social capital effect. Women who participate more in their communities may have enhanced access to information and/or resources, easier access to health care and support when they face maternal and fetal conditions that trigger the need for medical intervention. On the other hand, women may be more exposed to social and/or environmental stressors. Future research needs to distinguish between different types of participation and different components of social capital to better understand their associations with birth outcomes.     

妊娠期高血压疾病与妊娠结局的相关性

目的:分析妊娠期高血压疾病发病的高危因素以及孕期保健与并发症之间、治疗方案选择与妊娠结局的关系,探讨降低妊娠期高血压疾病的发生率、减少并发症的措施,从而改善母婴结局。方法:回顾性分析我院2004年7月~2006年6月妊娠期高血压疾病患者587例,分析其高危因素、孕期产检情况与并发症发生的比例,妊高征治疗方案选择与妊娠结局的关系。结果:妊娠期高血压疾病高危因素多为肥胖、高龄、精神紧张、双胎、营养差者;并发症的发生率与产检次数成反比,产检越正规、次数越多,并发症发生机会越少,正规产检与不正规产检及从不产检者并发症发生率分别为22.82%、37.41%、63.38%,三者比较P<0.01,差异有显著性;妊娠期高血压疾病实施规范治疗方案与否与早产、低出生体重儿、新生儿窒息、早期新生儿死亡、子痫、心衰、胎盘早剥,差异有显著性。结论:大力宣传孕产期保健知识,加强流动人口管理,提倡正规产检,严格执行妊高征处理规范及三级转诊制度,可减少妊娠期高血压疾病及其并发症,改善母婴结局。     

产妇及新生儿IGF2甲基化状态及其与新生儿出生结局的关系

目的:探讨母血及脐带血IGF2甲基化状态及其影响因素,评价健康产妇及新生儿脐血IGF2甲基化状态对新生儿出生结局的影响。方法:于2008年4～6月对82名住院产妇进行问卷调查,并采集产妇外周血及其新生儿脐带血,卧式身长计、头围尺分别测量新生儿身高和头围;电子秤称量新生儿体重。RT-PCR分析IGF2 P2、P3启动子区的甲基化状态。结果:新生儿平均身高为49.46 cm,平均体重为3.19 kg,平均头围为33.87 cm。母血IGF2 P2甲基化率的均值是3.00%,脐血是3.81%,脐血IGF2 P2甲基化率高于母血IGF2 P2甲基化率(P<0.01)。母血IGF2 P3甲基化率的均值是5.61%,脐血是4.34%,母血IGF2 P3甲基化率高于脐血IGF2 P3甲基化率(P<0.01)。多元线性回归模型结果显示新生儿IGF2 P2的甲基化状态与母体IGF2 P2的甲基化状态呈正相关(r=0.246,P<0.05),且新生儿IGF2 P3的甲基化状态与母体IGF2 P3的甲基化状态也呈正相关(r=0.428,P<0.01);母体IGF2 P2的甲基化状态与母亲孕期体重增加、被动吸烟史分别相关(分别r=0.234,P<0.05,r=0.242,P<0.05),母体IGF2 P3的甲基化状态还与母亲受教育程度高具有相关性(r=-0.239,P<0.05)。结论:产妇及新生儿脐血IGF2甲基化状态受环境因素影响,但对新生儿出生结局无明显影响。     

Birth outcome measures and maternal exposure to heavy metals (lead,cadmium and mercury) in Saudi Arabian population

This cross-sectional study was conducted to assess the association between exposure to heavy metals (lead, cadmium and mercury) during pregnancy and birth outcomes in 1578 women aged 16–50 years who delivered in Al-Kharj hospital, Saudi Arabia, in 2005 and 2006. The levels of lead, cadmium and mercury were measured in umbilical cord blood, maternal blood and the placenta. Outcome variables were anthropometric measures taken at birth, along with the risk of being small-for-gestational age (SGA). We selected the 10th percentile as the cutoff for dichotomizing measures of birth outcome. Cadmium, despite its partial passage through the placenta had the most prominent effect on several measures of birth outcome. After adjustment for potential confounders, logistic regression models revealed that crown-heel length (p = 0.034), the Apgar 5-minute score (p = 0.004), birth weight (p = 0.015) and SGA (p = 0.049) were influenced by cadmium in the umbilical cord blood. Significant decreases in crown-heel length (p = 0.007) and placental thickness (p = 0.022) were seen with higher levels of cadmium in maternal blood. As placental cadmium increased, cord length increased (p = 0.012) and placental thickness decreased (p = 0.032). Only lead levels in maternal blood influenced placental thickness (p = 0.011). Mercury in both umbilical cord and maternal blood was marginally associated with placental thickness and placental weight, respectively. Conversely, placental mercury levels significantly influenced head circumference (p = 0.017), the Apgar 5-minute score (p = 0.01) and cord length (p = 0.026). The predictions of these models were further assessed with the area under the curve (AUC) of the receiver operating curves (ROCs), which were modest (larger than 0.5 and smaller than 0.7). The independence of gestational age or preterm births on the observed effect of metals on some measures of birth outcome, suggested detrimental effects of exposure on fetal development. The magnitude of the estimated effects might not necessarily be of clinical significance for infants but may have a considerable public-health relevance given the high prevalence of exposure to heavy metals. Further research should be conducted to confirm these findings and to evaluate their long-term risks, if any.     

Metal levels in flathead sole (Hippoglossoides elassodon) and great sculpin (Myoxocephalus polyacanthocephalus) from Adak Island, Alaska: potential risk to predators and fishermen

Increasingly there is a need to assess the contaminant levels in fish as indicators of the health and well-being of both the fish and their consumers, including humans. This paper examines the levels of arsenic, cadmium, chromium, lead, manganese, mercury, and selenium in the kidney, liver, and muscle of great sculpin and flathead sole from Adak Island in the Aleutian Islands, Alaska. Both species are consumed by the local Aleuts and others. There were significant differences in the levels of heavy metals as a function of tissue for both fish species; the liver of sculpin and sole generally had the highest levels of most metals, except for arsenic, lead, and selenium. Sole had significantly higher mean levels of arsenic in kidney (32,384 vs. 531 ppb, wet weight), liver (18,954 vs. 2532 ppb), and muscle (19,452 vs. 1343 ppb) than did sculpin. Sole also had higher mean levels of cadmium (230 vs. 63 ppb), lead (1236 vs. 48 ppb), mercury (150 vs. 107 ppb), and selenium (5215 vs. 1861 ppb) in kidney than did sculpin. There were significant correlations among weight and length measurements for both species. However, except for mercury, there were few significant correlations among tissue types for most metals. Only mercury and manganese levels were significantly correlated with size for sculpin (but not for sole). Levels of arsenic, lead, and mercury may pose a risk to predators that consume them, and arsenic and mercury may pose a risk to human consumers.     

Neighborhood poverty,allostatic load,and birth outcomes in African American and white women: Findings from the Bogalusa Heart Study

As a biologically-mediated pathway between adversity and declines in physical health, allostatic load has been frequently hypothesized as a potential contributor to racial disparities in birth outcomes, but an empirical evidence is lacking. The purpose of this study was to examine the relationships between maternal preconception allostatic load, race, and adverse birth outcomes within the context of neighborhood-level poverty using data from the Bogalusa Heart Study. Allostatic load was quantified as a count of regulatory biomarkers falling in the highest risk quartile of the sample distribution as measured from a physical examination that took place prior to conception. Consistent with previous findings, African American women resided in more impoverished neighborhoods and had higher allostatic load scores compared to whites; however, allostatic load was not associated with preterm birth or low birth weight in fully adjusted models. These results underscore a need for further refinement of both biologic and contextual measures that capture holistically the way in which stressful conditions and experiences encountered across the life-course influence health potentials and engender inequities in reproductive health outcomes.     

Metal levels in eggs of common terns (Sterna hirundo) in New Jersey: temporal trends from 1971 to 2002

Managers and public policy makers require information on the status of and trends in contaminant levels in organisms to assess ecosystem health. Seabirds are excellent bioindicators because they are long-lived, feed at different trophic levels, and are at the top of the food chain, and many are abundant and widely distributed. They can reveal spatial or temporal trends in contaminant levels. In this paper, we examine temporal trends in the levels of cadmium, chromium, lead, manganese, mercury, and selenium in eggs from common terns (Sterna hirundo) nesting on several salt marsh islands in Barnegat Bay, New Jersey. We test the null hypothesis that there are no temporal differences in levels of cadmium, lead, and mercury from 1971 to 2002 and in chromium, manganese, and selenium from 1992 to 2002. Arsenic was also analyzed in recent years. Levels were highest for manganese, followed by selenium, mercury, arsenic, lead, chromium, and cadmium. The eggs of Barnegat Bay common terns show a decline in levels of cadmium, chromium, and lead. Mercury declined from 1971 to 1982, increased dramatically in 1999, and declined thereafter. Manganese, an essential element, showed a decline (except for 2001), and selenium declined initially, but then remained stable. The data indicate that common terns can serve as useful bioindicators of temporal trends in exposure and that some of the metals of concern in estuarine environments (lead, cadmium) have declined over the past 30 years, although mercury levels are higher than in the early 1980s. The spike in 1999 is unexplained.     

Prenatal bisphenol A and birth outcomes: MOCEH (Mothers and Children's Environmental Health) study

Bisphenol A (BPA) is used primarily in the production of polycarbonate plastics and epoxy resins. Widespread exposure to BPA has created a great deal of concern regarding its potential adverse effects on human health.This study examined the relationship between prenatal BPA exposure and birth outcomes, including birth weight, birth length, and ponderal index considering gender difference.A multi-center birth cohort study, Mothers and Children's Environmental Health (MOCEH) has been established in Korea since 2006. Study subjects are 757 pregnant women from the original cohort, who had their urinary BPA level measured during the third trimester, as well as information on birth outcome, prior medical history, psychosocial status, health behavior, environmental exposure as well as socio-demographic characteristics. Regression analysis was performed to assess the effect of BPA on birth outcome.The geometric mean concentration of BPA in pregnant women was 1.29 μg/L (1.87 μg/g creatinine) during late pregnancy. Urinary BPA concentrations were shown to be higher in women with a higher income level. Univariate regression analysis revealed a significant association between BPA levels and birth weight. In adjusted analysis, the second tertile of maternal BPA exposure exhibited an increase in birth weight, relative to the first tertile (p = 0.04). These relationships were more pronounced in male neonates. Also, prenatal exposure to BPA was associated with an increase of ponderal index in total, and especially female neonates.This study shows that the association of prenatal exposure to BPA with anthropometric measures, such as birth weight and birth length, differed by gender. Further study is required to more fully elaborate this relationship between prenatal BPA exposure and birth outcome.     

Urinary metal concentrations among mothers and children in a Mexico City birth cohort study

Personal care product use is a potential source of metals exposure among children, but studies have been limited. We measured urinary concentrations of 10 metals (aluminum, arsenic [As], barium [Ba], cadmium, cobalt [Co], lead [Pb], manganese [Mn], molybdenum [Mo], nickel, and zinc [Zn]) in third trimester pregnant women (n?=?212) and their children at 8–14 years of age (n?=?250). Demographic factors (child sex, age, socioeconomic status, and maternal education), body mass index (BMI) z-score, and child personal care product use in the 24?h prior to urine collection were examined as predictors of urinary metal concentrations. Metals were detected in 80–100% of urine samples, with significant differences in maternal versus childhood levels. However, metal concentrations were not strongly correlated within or between time points. In linear regression models including all demographic characteristics, BMI z-score, and specific gravity, age was associated with higher Co (6% [95% CI: 2, 10]), while BMI z-score was associated with lower Mo (-6% [95% CI: -11, -1). In addition, significantly higher metal concentrations were observed among users of colored cosmetics (Mo: 42% [95% CI: 1, 99]), deodorant (Ba: 28% [3, 58]), hair spray/hair gel (Mn: 22% [3, 45]), and other toiletries (As: 50% [9, 108]), as well as with an increasing number of personal care products used (As: 7% [3, 11]) after adjustment for child sex, age, total number of products used, and specific gravity. However, significantly lower metal concentrations were noted for users of hair cream (As and Zn: -20% [-36, -2] and -21% [-35, -2], respectively), shampoo (Pb: -40% [-62, -7]), and other hair products (Pb: -44% [-65, -9]). We found that personal care product use may be a predictor of exposure to multiple metals among children. Further research is recommended to inform product-specific exposure source identification and related child health risk assessment efforts.     

The hidden costs of terrorism: The effects on health at birth

We study the effects of in utero exposure to terrorism in Spain on birth outcomes, focusing on terrorism perpetrated by ETA during the period 1980–2003. We find that in utero exposure to terrorism early in pregnancy, as measured by the number of bomb casualties in the mother's province of residence in the first trimester of pregnancy, has detrimental effects on birth outcomes: in terms of average birth weight (lower), prevalence of low birth weight (higher) and fraction of “normal” babies (lower). While our findings are robust to a host of potential threats to validity, they seem to be driven by exposure to a relatively large number of bomb casualties. Focusing on the deadliest ETA terrorist attack, the Hipercor bombing of 1987 in Barcelona, we find substantial effects on birth outcomes. We then attempt to assess the mechanisms at stake by presenting evidence suggesting that exposure to bomb casualties decreases self-reported health and increases smoking among women, but not among men. While exposure to terrorism during conception does not affect total fertility, there seems to be a compositional change: during bombing periods, those women who conceive are more likely to be married, and married women tend to have better birth outcomes, on average. In addition, we find that exposure to bomb casualties increases fetal deaths. Thus, we interpret our estimated negative effects on health at birth as providing lower bounds to the true effects of in utero exposure to terrorism.     

Surrounding greenness and birth weight: Results from the GINIplus and LISAplus birth cohorts in Munich

AimWe investigated the association between surrounding greenness at the mother's residential address at the time of delivery and birth weight in two German birth cohorts and explored potential underlying hypotheses.MethodsComplete data on 3203 newborns, recruited in Munich between 1996 and 1999, were available. Surrounding greenness was defined using the mean of the Normalized Difference Vegetation Index, which was derived from Landsat 5 TM satellite images.ResultsAn interquartile increase of surrounding greenness in a 500-m buffer was associated with an average birth weight increase of 17.6 g (95% CI=0.5 to 34.6). The effect strengthened after individual adjustment for NO₂, PM2.5, distance to major road and population density. The strongest association was found for mothers with less than 10 years of school education. The results remained robust when additionally adjusted for noise or maternal stress during pregnancy. Neighbourhood green spaces were not associated with birth weight.ConclusionsSurrounding greenness at the birth address was positively associated with birth weight in two birth cohorts in Munich. The mechanisms driving this association remain unclear and warrant further investigation.     

The effect of e-cigarette indoor vaping restrictions on adult prenatal smoking and birth outcomes

We estimate the effect of county-level e-cigarette indoor vaping restrictions on adult prenatal smoking and birth outcomes using United States birth record data for 7 million pregnant women living in places already comprehensively banning the indoor use of traditional cigarettes. We use both cross-sectional and panel data to estimate our difference-in-difference models. Our panel model results suggest that adoption of a comprehensive indoor vaping restriction increased prenatal smoking by 2.0 percentage points, which is double the estimate obtained from a cross-sectional model. We also document heterogeneity in effect sizes along lines of age, education, and type of insurance.     

The sex-specific association between maternal paraben exposure and size at birth

Parabens are a group of esters of parahydroxybenzoic acid and are utilized as antimicrobial preservatives in the majority of personal care products (PCPs). Epidemiological studies regarding the adverse effects of parabens on fetuses are still limited. The aim of this study was to determine the association between maternal paraben exposure and birth outcomes.One hundred and ninety-nine pregnant women were enrolled, and maternal urine was collected in the third trimester. The urine concentrations of four parabens (methyl (MP), ethyl (EP), propyl (PP), and butyl (BP)) were determined by ultra-performance liquid chromatography coupled with quadrupole time-of-flight mass spectrometry. Generalized additive model-penalized regression splines and a multivariable regression model were employed to determine the association between paraben exposure levels and birth outcomes. A causal mediation analysis was conducted to determine the mediation effect of oxidative stress on birth outcomes.The geometric means of urinary MP, EP, PP, and BP were 51.79, 1.26, 4.21, and 1.25 μg/g cre., respectively. In the penalized regression splines, sex-specific associations between maternal MP levels and birth outcomes were observed; a downward curvature was observed between the MP level and birth weight, length, head circumference, and thoracic circumference among female newborns. Pregnant women in the group with MP levels above the third quartile had neonates with significantly lower body weight (β = −215.98 g, p value = 0.02) compared to those in the group with MP levels lower than the third quartile. No significant mediation of oxidative stress was observed between maternal MP exposure and female birth weight. The estimated proportion mediated ranged from −6% to 15%. The negative association between maternal paraben exposure and female birth outcomes in relation to child development should be carefully considered.     

The effect of prenatal maternity leave on short and long-term child outcomes

Maternity leave policies are designed to safeguard the health of pregnant workers and their unborn children. We evaluate a maternity leave extension in Austria which increased mandatory prenatal leave from 6 to 8 weeks. We exploit that the assignment to the extended leave was determined by a cutoff date. We find no evidence for significant effects of this extension on children's health at birth or long-term health and labor market outcomes. Subsequent maternal health and fertility are also unaffected. We conclude that employment during the 33rd and 34th week of gestation is not harmful for expecting mothers (without major problems in pregnancy) and their unborn children.