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Meta-Analysis
. 2023 Jan 11;13(1):563.
doi: 10.1038/s41598-022-27345-x.

Nitrate contamination in drinking water and adverse reproductive and birth outcomes: a systematic review and meta-analysis

Luling Lin  1 , Sophie St Clair  1 , Greg D Gamble  1 , Caroline A Crowther  1 , Lesley Dixon  2 , Frank H Bloomfield  1 , Jane E Harding  3
Affiliations
Meta-Analysis

Nitrate contamination in drinking water and adverse reproductive and birth outcomes: a systematic review and meta-analysis

Luling Lin et al. Sci Rep. .

Abstract

Exposure to low levels of nitrate in drinking water may have adverse reproductive effects. We reviewed evidence about the association between nitrate in drinking water and adverse reproductive outcomes published to November 2022. Randomized trials, cohort or case-control studies published in English that reported the relationship between nitrate intake from drinking water and the risk of perinatal outcomes were included. Random-effect models were used to pool data. Three cohort studies showed nitrate in drinking water is associated with an increased risk of preterm birth (odds ratio for 1 mg/L NO3-N increased (OR1) = 1.01, 95% CI 1.00, 1.01, I2 = 23.9%, 5,014,487 participants; comparing the highest versus the lowest nitrate exposure groups pooled OR (ORp) = 1.05, 95% CI 1.01, 1.10, I2 = 0%, 4,152,348 participants). Case-control studies showed nitrate in drinking water may be associated with the increased risk of neural tube defects OR1 = 1.06, 95% CI 1.02, 1.10; 2 studies, 2196 participants; I2 = 0%; and ORp = 1.51, 95% CI 1.12, 2.05; 3 studies, 1501 participants; I2 = 0%). The evidence for an association between nitrate in drinking water and risk of small for gestational age infants, any birth defects, or any congenital heart defects was inconsistent. Increased nitrate in drinking water may be associated with an increased risk of preterm birth and some specific congenital anomalies. These findings warrant regular review as new evidence becomes available.

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Conflict of interest statement

The authors declare no competing interests.

Figures

Figure 1
Figure 1
Flow diagram of included studies.
Figure 2
Figure 2
Forest plot for the association between nitrate in drinking water and preterm birth. (a) Linear relationship; (b) Highest versus lowest exposure; (c) All combined higher versus the lowest exposure.
Figure 3
Figure 3
Forest plot for the association between nitrate in drinking water and any birth defects. (a) Linear relationship; (b) Highest versus the lowest exposure; (c) All combined higher versus the lowest exposure.
Figure 4
Figure 4
Forest plot for the association between nitrate in drinking water and neural tube defects. (a) Linear relationship; (b) Highest versus the lowest exposure; (c) All combined higher versus the lowest exposure.
Figure 5
Figure 5
Forest plot for the association between nitrate in drinking water and any heart defects. (a) Highest versus the lowest exposure; (b) All combined higher versus the lowest exposure.
See this image and copyright information in PMC

References

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    1. Ministry of Health. Guidelines for drinking-water quality management for New Zealand (3rd edn) (Updated June 2019). Wellington: Ministry of Health; 2017.
    1. National Ground Water Association. Groundwater basics. Part 2. Groundwater Foundation 2021. https://www.groundwater.org/file_download/ebe1fe1e-c4cb-415e-b774-7556ac... . Accessed 15 Aug 2021.

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