Emmett Interdisciplinary Program in Environment and Resources, Stanford University, Stanford, California, USA.
Department of Epidemiology and Population Health, Stanford University, Stanford, California, USA.
Environ Health Perspect. 2021 May;129(5):57001. doi: 10.1289/EHP8205. Epub 2021 May 5.
Nitrate is a widespread groundwater contaminant and a leading cause of drinking water quality violations in California. Associations between nitrate exposure and select adverse birth outcomes have been suggested, but few studies have examined gestational exposures to nitrate and risk of preterm birth (before 37 wk gestation).
We investigated the association between elevated nitrate in drinking water and spontaneous preterm birth through a within-mother retrospective cohort study of births in California.
We acquired over 6 million birth certificate records linked with Office of Statewide Health Planning and Development hospital discharge data for California births from 2000-2011. We used public water system monitoring records to estimate nitrate concentrations in drinking water for each woman's residence during gestation. After exclusions, we constructed a sample of 1,443,318 consecutive sibling births in order to conduct a within-mother analysis. We used separate conditional logistic regression models to estimate the odds of preterm birth at 20-31 and 32-36 wk, respectively, among women whose nitrate exposure changed between consecutive pregnancies.
Spontaneous preterm birth at 20-31 wk was increased in association with tap water nitrate concentrations during pregnancy of 5 to [odds ratio ; 95% confidence interval (CI): 1.29, 1.67] and (; 95% CI: 1.49, 4.26) compared with (as nitrogen). Corresponding estimates for spontaneous preterm birth at 32-36 wk were positive but close to the null for 5 to nitrate (; 95% CI: 1.02, 1.15) and for nitrate (; 95% CI: 0.85, 1.31) vs. nitrate. Our findings were similar in several secondary and sensitivity analyses, including in a conventional individual-level design.
The results suggest that nitrate in drinking water is associated with increased odds of spontaneous preterm birth. Notably, we estimated modestly increased odds associated with tap water nitrate concentrations of 5 to (below the federal drinking water standard of ) relative to . https://doi.org/10.1289/EHP8205.
硝酸盐是一种广泛存在的地下水污染物，也是导致加利福尼亚州饮用水质量违规的主要原因。有研究表明，硝酸盐暴露与某些不良出生结局之间存在关联，但很少有研究调查妊娠期间接触硝酸盐与早产（妊娠 37 周前）的风险。
我们通过对加利福尼亚州的一项母亲内回顾性队列研究，调查饮用水中硝酸盐升高与自发性早产之间的关系。
我们获取了 2000 年至 2011 年期间超过 600 万份出生证明记录，并与加利福尼亚州医院分娩出院数据的州卫生规划和发展办公室相关联。我们利用公共供水系统监测记录来估算每位女性妊娠期间居住地饮用水中的硝酸盐浓度。排除后，我们构建了一个包含 1443318 例连续兄弟姐妹出生的样本，以便进行母亲内分析。我们分别使用条件逻辑回归模型来估计妊娠期间硝酸盐暴露在连续妊娠之间变化的女性在 20-31 周和 32-36 周时早产的几率。
与饮用硝酸盐浓度为 相比，妊娠期间饮用硝酸盐浓度为 5 至 [比值比；95%置信区间（CI）：1.29，1.67]和 [95%CI：1.49，4.26]与 （作为氮）相比，20-31 周自发性早产的几率增加。对于 32-36 周自发性早产，5 至 硝酸盐 [95%CI：1.02，1.15]和 硝酸盐 [95%CI：0.85，1.31]的估计值为正，但接近零。在包括常规个体水平设计的几种二次和敏感性分析中，我们的发现相似。
结果表明，饮用水中的硝酸盐与自发性早产的几率增加有关。值得注意的是，与 相比，我们估计与自来水中硝酸盐浓度 5 至 （低于联邦饮用水标准 ）相关的几率略有增加。https://doi.org/10.1289/EHP8205。
