Prenatal exposure to PCDDs/PCDFs and dioxin-like PCBs in relation to birth weight

Several human studies have shown that low-level exposure to environmental contaminants, such as polychlorinated biphenyls (PCBs) and organochlorine pesticides, negatively influences birth outcomes. However, the effects of low-level exposure to polychlorinated dibenzo-p-dioxins (PCDDs), polychlorinated dibenzofurans (PCDFs), and dioxin-like PCBs (DL-PCBs) on birth outcomes have not been clarified in human studies.A prospective cohort study was established to investigate the possible adverse effects of PCDDs/PCDFs and DL-PCBs on fetal growth and neurodevelopment. We recruited 514 pregnant women between July 2002 and October 2005 in Sapporo, Japan. We measured 29 congener levels of PCDDs/PCDFs and DL-PCBs in maternal blood.Using multiple liner regression analysis of the association between birth weight and the levels of PCDDs/PCDFs and DL-PCBs with full adjustments for potential confounders, a significant adverse effect was observed regarding total PCDDs toxic equivalents (TEQ) levels (adjusted β=−231.5 g, 95% CI: −417.4 to −45.6) and total PCDFs TEQ levels (adjusted β=−258.8 g, 95% CI: −445.7 to −71.8). Among male infants, significant adverse associations with birth weight were found for total PCDDs TEQ level, total PCDDs/PCDFs TEQ level, and total TEQ level. However, among female infants, these significant adverse associations were not found. With regard to individual congeners of PCDDs/PCDFs and DL-PCBs, we found significantly negative association with the levels of 2,3,4,7,8-PeCDF (adjusted β=−24.5 g, 95% CI: −387.4 to −61.5).Our findings suggest that prenatal low-level exposure to PCDDs and PCDFs, especially 2,3,4,7,8-PeCDF, may accumulate in the placenta and retard important placental functions, which result in lower birth weight.     

Prenatal lead exposure in relation to gestational age and birth weight: A review of epidemiologic studies

Although the adverse effect on pregnancy outcomes at high levels of lead exposure in the workplace has been recognized for years, there is uncertainty regarding the impact of exposure at the lower community exposure levels commonly encountered today. This review summarizes the epidemiologic literature and discusses pertinent methodologic issues and possible sources of interstudy variation. The authors conclude that prenatal lead exposure is unlikely to increase the risk of premature membrane rupture but does appear to increase the risk of preterm delivery. Whether prenatal lead exposure decreases gestational age in terms of infants is unclear. Prenatal lead exposure also appears to be associated with reduced birth weight, but results vary in relation to study design and degree of control for confounding. Adjustment for gestational age, a possible confounder of the birth weight-lead exposure association, did not yield clearer results.     

Prenatal exposure to mercury and neurobehavioral development of neonates in Zhoushan City, China

Exposure to hazardous Hg can adversely affect children's neurodevelopment. However, few data are available on either Hg levels in neonates and their mothers or the impact of prenatal exposure to Hg on neonates' neurobehavioral development in the Chinese population. Therefore, this study examined Hg levels in neonates and their mothers and the relationship between prenatal exposure to Hg and neonates' neurobehavioral development in Zhoushan City, Zhejiang Province, China. Between August and October 2004, 417 women who delivered their babies at Zhoushan Women's and Children's Health Hospital, an island city in east China were invited to take part in this study. A total of 408 complete questionnaires, 405 maternal hair samples, and 406 umbilical cord samples were collected. Neonatal behavioral neurological assessments (NBNA) were conducted for 384 neonates. The geometric mean (GM) of Hg level in cord blood was 5.58 microg/L (interquartile range: 3.96-7.82 microg/L), and the GM of maternal hair Hg level was 1246.56 microg/kg (interquartile range: 927.34-1684.67 microg/kg), a level much lower than other reported fish-eating populations, indicating Hg exposure in Zhoushan city is generally below those considered hazardous. However, according to the reference dose of Hg levels (RfD 5.8 microg/L) derived by EPA, 69.9% of newborns had levels at or above the RfD, an estimated level assumed to be without appreciable harm. There was a strong correlation between maternal hair and cord blood Hg levels (r = 0.82, P < 0.01). Frequency of fish consumption was associated with hair Hg (r = 0.48, P < 0.01) and cord blood Hg levels (r = 0.54, P < 0.01). Increased prenatal Hg exposure was associated with decreased behavioral ability for males (OR = 1.235, 95%CI of OR = 1.078-1.414, P < 0.001), but not for females. Our results provide some support for the hypothesis that there is neurodevelopmental risk for males from prenatal MeHg exposure resulting from fish consumption. But the findings of this study may be due to chance, and long-term follow-up research is needed to evaluate cumulative effects of exposure to mercury.     

Residential proximity to heavy traffic and birth weight in Shizuoka, Japan

An association between exposure to traffic-related air pollution and reduced birth weight has been suggested. However, previous studies have failed to adjust for maternal size, which is an indicator of individual genetic growth potential. Therefore, we evaluated the association of air pollution with birth weight, term low birth weight (term-LBW), and small for gestational age (SGA), with adjustment for maternal size. Individual data were extracted from a database that is maintained by a maternal and perinatal care center in Shizuoka, Japan. We identified liveborn singleton births (n=14,204). Using geocoded residential information, each birth was assigned a number of traffic-based exposure indicators: distance to a major road; distance-weighted traffic density; and estimated concentration of nitrogen dioxide by land use regression. The multivariate adjusted odds ratios and their 95% confidence intervals (CIs) for the associations between exposure indicators and outcomes were then estimated using logistic regression models. Overall, exposure indicators of air pollution showed no clear pattern of association. Although there are many limitations, we did not find clear associations between birth-weight-related outcomes and the three markers of traffic-related air pollution.     

Pesticide exposure and low birth weight prevalence in Brazil

Introduction

Brazil is one of the major global consumers of pesticides and exposure to these substances can affect fetal growth.

Objective

To estimate the correlation between pesticide sales in 1996 and the prevalence of low birth weight during the period 1996–1998 in Brazil.

Method

This ecological study employed secondary data aggregated at the level of Brazilian micro-regions (cluster of cities). Prevalence of low birth weight in 1996, 1997, and 1998 was obtained from the Brazilian health databases, and per capita pesticides sales in 1996 obtained from the Brazilian Institute of Geography and Statistics were utilized as an indirect measure of population exposure to these chemicals. Spearman correlation coefficient and Prevalence Ratio by quartiles were estimated, considering per capita pesticide sales and the prevalence of low birth weight.

Results

A total of 552 micro-regions were analyzed (446 non-urban and 106 urban). In rural areas, the per capita pesticide sales were directly associated with higher prevalence of children born with low birth weight (r = 0.403), with birth weights between 1500 and 2500 grams (r = 0.366), and very low birth weight birth (r = 0.476). All correlations were statistically significant (p < 0.001). On the other hand, in urban areas there was no significant correlation. There was a gradual increase in the prevalence of low birth weight according to the quartiles of pesticide consumption.

Conclusions

Pesticide per capita sales may affect the prevalence of newborns with low birth weight in non-urban micro-regions of Brazil, indicating the need to strengthen policies and actions to protect the health of populations exposed to pesticides.     

Prenatal exposure to wood fuel smoke and low birth weight

BACKGROUND: Maternal exposure to wood fuel smoke may lead to impaired fetal growth due to hypoxia and or oxidative stress from smoke constituents such as carbon monoxide and particulate matter. OBJECTIVES: We studied the risk of low birth weight (LBW) and reduced mean birth weight in relation to reported use of wood for cooking during the prenatal period, compared with natural gas (NG). METHODS: We studied a historical cohort of women who had a singleton live birth in the years 2000-2002, from a semirural area of Pakistan. Infant's birth weight was obtained from records, and prenatal records had data for maternal body mass index and parity. Cooking habits, daytime sleep habits, and type of fuel used during the pregnancies in 2000-2002 were ascertained by a survey done in 2004-2005. We performed multiple linear and logistic regression modeling using propensity scores to adjust for confounding variables. RESULTS: Unadjusted mean (+/- SD) birth weight was 2.78 +/- 0.45 kg in wood users, and 2.84 +/- 0.43 kg (p < 0.06) in NG users. Infants born to wood users averaged 82 g lighter than infants born to NG users when weight was adjusted for confounders (p < 0.07). The rate of LBW (< 2,500 g) was 22.7% among wood users compared with 15.0% in NG users (p < 0.01), for an adjusted relative risk of 1.64 (95% confidence interval, 1.10-2.34). The population attributable risk for LBW explained by wood use was estimated to be 24%. CONCLUSION: Cooking with wood fuel during pregnancy, a potentially modifiable exposure, was associated with LBW and marginally lower mean birth weight compared with using NG.     

孕中期血糖水平与新生儿出生体重的队列研究

目的 探讨孕中期孕妇75 g口服糖耐量试验(OGTT)的3项血糖值与出生体重的关系。方法 参与前瞻性队列研究的3 081名孕妇于孕≤14周时收集基础人口统计学信息,在孕24～28周行75 g OGTT,利用多项logistic回归法分析新生儿出生体重的影响因素及孕中期FPG和OGTT-1 h、OGTT-2 h值四分位分组的大于胎龄儿(LGA)发生风险,以多元线性回归法分析血糖值与新生儿出生体重的关系。结果 孕前超重(24.0 kg/m²≤BMI <28.0 kg/m²)(OR=1.4,95%CI:1.0～2.0,P=0.029)、妊娠期糖尿病(OR=2.4,95%CI:1.8～3.2,P <0.001)是LGA发生的危险因素;孕前消瘦(BMI <18.5 kg/m²)(OR=1.6,95%CI:1.2～2.2,P=0.003)、子痫前期(OR=4.0,95%CI:1.9～8.4,P <0.001)可增加小于胎龄儿出生的风险。多元线性回归分析调整孕前BMI、产次、高血压情况、新生儿性别后,FPG、OGTT-1 h和OGTT-2 h均与新生儿出生体重呈正相关关系(β 值分别为91.99、33.60、32.00,P值均 <0.001)。随着孕妇3项血糖水平四分位升高各组出生体重呈增大趋势,且LGA发生风险逐渐增大。结论 孕中期血糖水平与子代出生体重呈正相关。随着血糖水平升高,新生儿出生体重增大,LGA发生风险升高,但小于胎龄儿与血糖无关联。FPG值对发生LGA有很好的预测作用。     

Factors influencing birth weight in newborns of diabetic and non-diabetic women a population based study

Maternal diabetes is known to be related to an increase in birth weight of the offspring. However, the mechanism of the association is not entirely clear. In addition, the contribution of the demographic, obstetric and metabolic factors to birth weight in diabetic mothers is not well defined. All the diabetic women (68 requiring insulin-treatment and 403 on diet alone) and a random sample of 1 in 12 of all non-diabetic women (893 women) who delivered in one regional hospital between March 1987 and June 1988 inclusive, were included in the study. Tests for gestational diabetes are routinely performed in our pregnant women population, thus, the study is a population based one. The mean birth weight of infants of diabetic mothers adjusted for gestational age was higher than in those of non-diabetic mothers. However, no relationship was found between maternal glycosylated hemoglobin measured at delivery and the infants birth weight. Furthermore, at each week of gestation, infants born to diabetic mothers were heavier than the infants of non-diabetic mothers (for weeks 37 to 40, p < 0.05), while no differences were found in glycosylated hemoglobin levels between the two groups at any time. In a multivariate model we showed that after controlling for gestational age, the only factors which independently and significantly affected birth weight in our population were diabetes, ethnic origin, and the parity of the mother. Our findings support the possibility that substances which induce hyperinsulinemia, other than glucose, may be related to the higher birth weight of infants of diabetic mothers.     

Aircraft noise and birth weight

Summary Data from six infant welfare centres in the vicinity of Amsterdam airport were analysed. Birth weights of 902 infants were related to aircraft noise levels to which the mother was exposed in pregnancy. The analysis was restricted to deliveries in hospital, single births and mothers aged 20–34 years.In high noise areas the mean birth weight was 69 g lower than in low noise areas. Of the infants in high noise areas 24% had a birth weight less than 3000g, compared with 18% in low noise areas.In the analysis the effect of sex of the infant, birth order and to some extent socio-economic status were taken into account. An effect of smoking seemed unlikely. The results, together with existing knowledge, give some suggestion that aircraft noise can decrease birth weight.     

Maternal anthropometric measurements and other factors: relation with birth weight of neonates

The objective of this study was to examine the influence of anthropometric measurements of pregnant women, gestational weight gain, fundal height, and maternal factors, namely age, education, family income, parity along with maternal hemoglobin, on birth weight of neonates. A cross sectional study was performed in Khoy City in north west of Iran. Four hundred and fifty healthy pregnant women in the age between 16-40 years were selected for this study from seven health urban centers and one referral hospital. Findings showed that the mean age, height, fundal height, maternal weight, and gestational weight gain during pregnancy were 26.1 years, 159.1 cm, 32.9 cm, 72.0 kg, 11.8 kg respectively. The mean birth weight of neonates was 3.2 kg and 11% of neonates showed low birth weight. Age, family income, maternal height, weight, gestational weight gain and fundal height were significantly associated with birth weight of neonates. Using binary logistic regression analysis, fundal height, maternal hemoglobin, family income and gestational weight gain of pregnant women could be considered as predictive factors of birth weight of neonates.     

The influence of age at exposure to PBBs on birth outcomes

The determination of critical windows of susceptibility to environmental chemical exposures and health has become a major public health focus. This study examined the association between early age at exposure to polybrominated biphenyls (PBBs) and subsequent birth weight and gestational length in offspring among females. The study population consisted of 1111 births that occurred among 560 women enrolled in the Michigan PBB Cohort from 1975 to 1994. Maternal age at exposure was categorized into three groups:<10 years (n = 64), 11-16 years (n = 149), and 17-42 years (n = 347). Overall serum PBB levels ranged from 0 to 1490 ppb, with a median of 2, 3, and 2 ppb in the three age groups, respectively. Separate mixed-effects linear regression models were used to evaluate the effect of age at exposure (years) and initial PBB level (ppb) on birth weight (grams) and gestational age (weeks), controlling for gestational age (weeks) (in the model examining effects on birth weight), BMI (kg/m(2)) and serum PCB level at enrollment (ppb), maternal age and paternal education at delivery, parity, infant gender, interval between the initial serum test and date of delivery (years), and the trimester in which prenatal care was initiated. Relative to the oldest age group, age<10 years at exposure was the most important predictor of increased birth weight (estimated regression coefficient = 225 g, P = 0.012). Infant birth weight increased approximately 16 g for every 10 ppb increase in serum PBBs (P=0.004). There was no association between initial PBB levels and gestational age, nor were initial serum PCB levels associated with either infant birth weight or gestational length. These results provide support for the hypothesis that early age at exposure may be an important determinant in subsequent health effects due to environmental chemical exposures.     

母亲一般情况及生活方式与新生儿出生体重的关系

目的了解厦门地区孕妇一般情况、生活方式对新生儿出生体重（Birth Weight,BW）的影响,为孕中期保健干预策略和措施制定提供参考。方法前瞻性队列研究,2009年1月～11月于厦门市妇幼保健院产前保健门诊随机选取符合条件对象,进行孕妇生活方式调查,追踪妊娠结局并对孕产妇和新生儿出生体重进行测量。与新生儿出生体重相关的各种可能因素采用多元线性回归与logistic回归分析,未选入模型但临床认为较有意义的变量进行非参数和χ2检验,P〈0.05为差异有统计学意义。结果完整问卷440例,追踪至分娩结局417例,失访23例（5.23%）。非条件logistic回归分析（α入=0.10,α出=0.11）发现孕后运动（B〈0,OR〈1,P=0.019）和孕后做家务（B〈0,OR〈1,P=0.035）是BW异常的保护因素;χ2检验（α=0.10）表明孕前BMI异常及无怀孕史的妇女,其BW异常率较高（P〈0.10）;多元线性回归（逐步回归法、前进法、后退法,α入=0.10,α出=0.11）发现孕前BMI（b〉0,P〈0.05）、电梯使用（b〉0,P〈0.05）与BW呈正相关,被动吸烟（b〈0,P=0.088）与BW呈负相关;非参数秩和检验（α=0.05）表明根据恩格尔系数,家庭小康和富裕的BW最高,而温饱及以下生活水平的BW最低;孕期吸烟暴露造成BW随着被动吸烟时间增加不断降低（P〈0.05）。结论孕妇尽量避免烟雾暴露,适当运动,做些力所能及的家务,有利于BW的控制。     

Prenatal maternal blood triglyceride and fatty acid levels in relation to exposure to di(2-ethylhexyl)phthalate: a cross-sectional study

Objectives

The hypolipidemic effects of di(2-ethylhexyl)phthalate (DEHP) exposure in humans have not been investigated. And the influences of maternal prenatal DEHP exposure on birth outcomes are not well-known. We aimed to estimate prenatal DEHP exposure in maternal blood, and evaluate its relationships to maternal blood triglyceride (TG) and fatty acid (FA) levels and to birth outcomes.

Methods

We studied 318 mother–newborn pairs residing in Sapporo, Japan. Blood was taken one time during pregnancy for each mother. Maternal and infant characteristics were obtained from medical records and questionnaire survey. We measured DEHP metabolite, mono(2-ethylhexyl) phthalate (MEHP), along with TG and 9 FAs using maternal blood, and analyzed associations of MEHP level with maternal blood TG/FA levels and infant birth dimensions.

Results

Maternal blood TG and palmitoleic/oleic acid levels were higher, but stearic/docosahexaenoic acids and MEHP were lower during late pregnancy. Maternal blood MEHP levels inversely correlated with TG and palmitic/palmitoleic/oleic/linoleic/α-linolenic acids. After adjustment for confounders, we found that a tenfold increase in blood MEHP levels correlated with a decrease in TG of 25.1 mg/dl [95 % confidence interval (CI) 4.8–45.3 mg/dl], and similar relations in palmitic (β = −581.8; 95 % CI −906.5, −257.0), oleic (β = −304.2; 95 % CI −518.0, −90.5), linoleic (β = −348.6; 95 % CI −510.6, −186.6), and α-linolenic (β = −6.3; 95 % CI −9.5, −3.0) acids. However, we observed no correlations between maternal blood MEHP levels and infant birth weight, length, chest circumference, or head circumference.

Conclusions

Ambient DEHP exposure during pregnancy inversely correlated with maternal blood TG and 4 FA levels, but not birth outcomes.     

Pregnancy phthalate metabolite concentrations and infant birth weight by gradations of maternal glucose tolerance

Background

Higher birth weight is an important adverse outcome associated with hyperglycemia in pregnancy. Recent studies suggest that phthalate exposure is associated with elevated glucose levels in pregnant women, with implications for higher birth weight in the offspring. No study to date has investigated the association between prenatal phthalate exposure on infant high birth weight accounting for the range of pregnancy glucose levels.

出生体重与分娩方式的变化分析

目的 探讨本院近19年来足月妊娠,头位分娩,无合并症的产妇年龄、孕周、出生体重和分娩方式的变化及意义。方法 26 479例产妇资料被输入计算机,采用SSPS软件进行相关性分析、t检验和卡方检验。结果 随年代递增,产妇年龄逐渐增大,孕周减小,出生体重增加。阴道产率下降,剖宫产率上升,产钳助产率变化无规律。男女婴比例接近,男婴出生体重高于女婴,随年代不同,两者均增长,但增长幅度呈下降趋势。结论 近十几年来,胎儿出生体重逐渐增加,剖宫产率上升,男女婴比例略高于1:1。     

广州市孕妇室内烧香暴露对出生体重和胎盘重量影响的前瞻性队列研究

目的 探索孕妇孕期烧香对出生体重和胎盘重量的影响,为降低不良妊娠结局的发生风险提供依据。方法 基于前瞻性出生队列,在医院产科门诊和住院部收集资料,采用多重线性回归模型分析孕妇佛香和蚊香焚烧暴露与出生体重和胎盘重量的关系。结果 共纳入4 038对母婴。与无佛香暴露者相比,高频烧佛香的孕妇胎盘重量降低5.43 g（95%CI:- 9.94～- 0.91）。与无蚊香暴露者相比,蚊香暴露为高频孕妇的新生儿出生体重降低56.76 g（95%CI:- 110.31～- 3.22）。结论 孕妇孕期应减少室内烧香暴露,避免其引起的出生体重和胎盘重量下降。     

孕期空气污染物暴露与活产单胎新生儿出生体重的关联性分析

目的 应用多元线性模型探讨孕期不同空气污染暴露与出生体重之间的关联性。方法 采用多阶段随机抽样方法,自行设计问卷调查2010-2013年西安市曾经怀孕的育龄妇女及其生育子女,最终共纳入4 631例产妇。污染数据和气象资料由常规监测数据整理获得。根据母亲孕周和分娩日期计算孕妇各孕期污染物个体暴露水平。分别以不同孕期空气污染暴露（单污染物、双污染物、三污染物）和子女出生体重作为自变量和因变量,通过逐步校正混杂因素共建立3个多元线性模型,其中模型一仅分析空气污染暴露变量,模型二在模型一的基础上进一步校正母亲及新生儿个体差异因素,模型三在模型二的基础上进一步校正气象因素。结果 不同性别、孕周、母亲生育年龄、母亲文化程度、户籍、家庭经济情况分组的婴儿,其出生体重差异有统计学意义（P<0.01）。考虑污染物的协同作用后,模型一的差异无统计学意义（P>0.05）,孕中期接触NO₂的平均浓度每增加10 μg/m³,出生体重会减少13.3 g（模型二减少10.9 g）,接触PM₁₀每增加10 μg/m³,出生体重减少6.6 g（模型二减少5.9 g）;孕晚期接触NO₂每增加10 μg/m³,出生体重减少13.7 g（模型二减少9.8 g）。结论 控制气象因素后,孕中期NO₂、PM₁₀的暴露水平以及孕晚期NO₂的暴露对婴儿出生体重具有负效应。     

Cerebellar thiol status and motor deficit after lactational exposure to methylmercury

This study examined the exclusive contribution of methylmercury (MeHg) exposure through maternal milk on biochemical parameters related to the thiol status (glutathione (GSH) levels, glutathione peroxidase (GPx) and glutathione reductase (GR) activities) in the cerebellums of suckling mice. The same biochemical parameters were also evaluated in the cerebellums of mothers, which were submitted to a direct oral exposure to MeHg (10 mg/L in drinking water). With regard to the relationship between cerebellar function and motor activity, the presence of signs of motor impairment was also evaluated in the offspring exposed to MeHg during lactation. After the treatment (at weaning period), the pups lactationally exposed to MeHg showed increased levels of mercury in the cerebellum compared to pups in the control group and a significant impairment in the motor performance in the rotarod apparatus. In addition, these pups showed decreased levels of GSH in the cerebellum compared to pups in the control group. In dams, MeHg significantly increased the levels of cerebellar GSH and the activities of cerebellar GR. However, this was not observed in pups. This study indicates that (1) the exposure of lactating mice to MeHg causes significant impairments in motor performance in the offspring which may be related to a decrease in the cerebellar thiol status and (2) the increased GSH levels and GR activity, observed only in the cerebellums of MeHg-exposed dams, could represent compensatory pathophysiologic responses to the oxidative effects of MeHg toward endogenous GSH.     

Low birth weight in newborns to women employed in jobs with frequent exposure to organic solvents

The effects of occupational exposure to organic solvents in pregnancy on foetal growth are still unclear. Our aim was to study whether live newborns to women employed in paid jobs with frequent exposure had a different risk of being born with low birth weight (LBW), compared to those of women in jobs without such exposure. The study population was all singleton newborns delivered in the industrial township of Mon?egorsk (N?=?26,415). Information about occupation and characteristics of the mothers and babies was obtained from the local population-based birth register, and registered job function was used to classify exposure. We observed an elevated risk of LBW among live, singleton newborns in the exposed group (adjusted odds ratio: 1.68 [95% CI: 1.18–2.41]), which predominantly consisted of painters. The adjusted odds of LBW in the exposed group were also higher among term-born neonates. In addition, a lower mean birth weight was observed among the exposed.