Abstract

Background:

High levels of nitrate (${\mathrm{NO}}_3^{-}$) in drinking water cause methemoglobinemia in infants; however, few studies have examined the potential effects of low-level exposure on fetal growth, and the results have been inconsistent.

Objectives:

We sought to assess the association between maternal exposure to nitrate in drinking water during pregnancy and offspring size at birth in a nationwide study of full-term ($\ge 37\text{\hspace{0.17em}wk}$ gestation) live-born singletons.

Methods:

We estimated maternal nitrate exposure for 898,206 births in Denmark during 1991–2011 by linkage of individual home address(es) with nitrate data from the national monitoring database. Maternal address during pregnancy, infant size at birth [i.e., birth weight, low birth weight (LBW), body length, and birth head circumference] and covariates were compiled from the Danish Civil Registration System, the Danish Medical Birth Register, and The Integrated Database for Longitudinal Labor Market Research. Linear and logistic models with generalized estimating equations were used to account for multiple births to an individual. Nitrate exposure was modeled using five categories and as a log-transformed continuous variable.

Results:

There was evidence of a decreasing trend in models for term birth weight using categorical or continuous measures of exposure. Modeling exposure continuously, a difference of $-9.71\mathrm{g}$ (95% confidence interval: $-14.60$, $-4.81$) was predicted at $25\text{\hspace{0.17em}mg}/\mathrm{L}$ (half the value of the European Union drinking water standard) compared with $0\text{\hspace{0.17em}mg}/\mathrm{L}{\mathrm{NO}}_3^{-}$. Body length also decreased as nitrate concentrations increased in categorical and continuous models. There was little evidence of an association between ${\mathrm{NO}}_3^{-}$ and head circumference or LBW.

Discussion:

Although the estimated effects were small, our findings for live singleton births to Danish-born parents suggest that maternal intake of nitrate from drinking water may reduce term birth weight and length, which are markers of intrauterine growth. However, there was little evidence for an association between nitrate and head circumference or LBW. Future studies in other populations and with data on dietary sources of nitrate are encouraged to confirm or refute these findings. https://doi.org/10.1289/EHP7331

中文翻译：

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产前暴露于饮用水中的硝酸盐和胎儿生长受限的标志物：一项针对近 100 万丹麦出生儿童的人口研究

摘要

背景：

硝酸盐含量高（${不}_3^{-}$) 在饮用水中引起婴儿高铁血红蛋白血症；然而，很少有研究考察低水平暴露对胎儿生长的潜在影响，结果也不一致。

目标：

我们试图在一项全国性的足月研究中评估母亲在怀孕期间接触饮用水中的硝酸盐与出生时的后代大小之间的关联。$\ge 37\text{\hspace{0.17em}周}$ 妊娠）活产单身人士。

方法：

我们通过将个人家庭住址与来自国家监测数据库的硝酸盐数据联系起来，估计了 1991-2011 年丹麦 898,206 名新生儿的硝酸盐暴露情况。怀孕期间的母亲地址、出生时婴儿的大小 [即出生体重、低出生体重 (LBW)、身长和出生头围] 和协变量来自丹麦民事登记系统、丹麦医疗出生登记册和综合纵向劳动力市场研究数据库。使用具有广义估计方程的线性和逻辑模型来解释一个人的多胞胎。硝酸盐暴露使用五个类别建模，并作为对数转换的连续变量。

结果：

有证据表明使用分类或连续暴露测量的足月出生体重模型呈下降趋势。造型曝光连续，差异$-9.71\mathrm{G}$ （95% 置信区间： $-14.60$, $-4.81$) 被预测为 $25\text{\hspace{0.17em}毫克}/\mathrm{升}$ （欧盟饮用水标准值的一半）与 $0\text{\hspace{0.17em}毫克}/\mathrm{升}{不}_3^{-}$. 随着分类和连续模型中硝酸盐浓度的增加，体长也减少了。几乎没有证据表明两者之间存在关联${不}_3^{-}$ 和头围或LBW。

讨论：

尽管估计的影响很小，但我们对丹麦出生父母的活单胎分娩的研究结果表明，母亲从饮用水中摄入硝酸盐可能会降低足月出生的体重和长度，这是宫内生长的标志。然而，几乎没有证据表明硝酸盐与头围或 LBW 之间存在关联。鼓励未来在其他人群中进行研究并利用硝酸盐膳食来源的数据来证实或反驳这些发现。https://doi.org/10.1289/EHP7331