Table 1 Study characteristics.
Study name | Country, Region | Study design | Years of outcome ascertainment | Exposure description | Perinatal outcomes reported |
|---|---|---|---|---|---|
Cedergren 200232 | Sweden, Östergötland County | Retrospective cohort study | 1982–1996 | Maternal addresses linked to water supplies using a geographic information system Exposure measured period: samples represent nitrates in drinking water in either periconceptional or pregnancy period | Any cardiac defect |
Ebdrup 202233 | Denmark | Cohort study | 1996–2002 | Nitrate in drinking water estimates were taken from the national drinking water quality monitoring database, Jupiter. Individual-level household exposure estimates were obtained through the geocoded residential history for every person registered in the Danish Civil Registration System, and these estimates were linked with water supply areas Exposure measure period: the date of the last menstrual period (LMP) to the date of pregnancy outcome or end of follow-up, whichever came first | Spontaneous pregnancy losses |
Sherris 202134 | US, California | Retrospective cohort study | 2000–2011 | Geocoded residences were linked to water supplies, and public monitoring records of nitrate levels were used. Births were then assigned to exposure categories (low, medium, high) Exposure measured period: duration of the pregnancy | Preterm birth |
Stayner 2022 | |||||
Coffman 202113 | Denmark | Prospective cohort study | 1991–2011 | Nitrate in drinking water estimates were taken from the Danish national geodatabase, Jupiter. The residential addresses of mothers were taken from the Danish Civil Registration System. Exposure was assigned per month of pregnancy and then time-weighted averages used to calculate an overall pregnancy exposure. Data linkage was done using the unique personal identification number assigned to each resident in Denmark Exposure measured period: duration of the pregnancy | Low birth weight, birth weight, body length, head circumference |
Coffman 202235 | 1991–2015 | Unique personal identification number assigned to each liveborn resident in Denmark linked to household level of nitrate in drinking water from the Danish national monitoring geodatabase Jupiter and Danish Medical Birth Registry Exposure measured period: averaged nitrate over the pregnancy (accounting for changes in maternal address) | Preterm birth | ||
Stayner 202236 | 1991–2013 | Maternal addresses linked to the national monitoring database, Jupiter, which contains drinking water monitoring data Exposure measured period: averaged nitrate over the pregnancy (accounting for changes in maternal address) | Birth defects | ||
Thomsen 202137 | 1997–2017 | Maternal addresses from Danish Civil Registration System linked to the national monitoring database, Jupiter, which contains drinking water monitoring data Exposure measured period: first 22 weeks of pregnancy | Stillbirth | ||
Migeot 2013 | |||||
Migeot 201338 | France, Deux-Sèvres | Historic cohort study | 2005–2009 | Measurements of nitrate in community water systems (263 municipalities) were linked to maternal place of residence on the date of birth Exposure measured period: second trimester (taking season into account) | SGA births |
Limousi 201439 | 2005–2010 | SGA births | |||
Albouy-Llaty 201640 | 2005–2010 | Preterm birth | |||
Arbuckle 198841 | Canada, New Brunswick | Population- based case–control study | 1973–1983 | Water samples (3 samples of flushed drinking water) from households of the study subjects were collected to estimate the nitrate concentrations Exposure measured period: not specified | Central nervous system malformation |
Aschengrau 198942 | US, Massachusetts, Boston | Case–control study | 1976–1978 | Residential addresses at the time of pregnancy matched to routinely collected drinking water data. The information on drinking water source (surface, ground, or mixed) and treatment (chlorination or chloramination) for surface water were considered Exposure measured period: not specified | Spontaneous abortion |
Aschengrau 199343 | US, Massachusetts, Boston | Case–control study | 1977–1980 | Residential addresses at the time of pregnancy matched to routinely collected drinking water data Exposure measured period: during the first trimester | Congenital anomaly, stillbirth, neonatal death |
Brender 200444 | US, Texas-Mexico Border Counties | Case–control study | 1995–2000 | Water samples collected from the residential address were measured for nitrates Exposure measured period: not specified, samples meant to approximate pregnancy period | Neural tube defects |
Brender 201328 | US, Iowa and Texas | Population-based case–control study | 1997–2005 | Maternal addresses linked to public water utility nitrate measurements; nitrate ingestion (NO3−) estimated from reported water consumption Exposure measured period: 1 month before conception through the end of the third month of pregnancy; or 1 month before conception through 1-month post-conception for neural tube defects | Neural tube defects, limb deficiencies, oral cleft defects, congenital heart defects |
Croen 200145 | US, California | Population-based case–control study | 1989–1991 | Maternal addresses linked to water companies by city or Department of Health Services Water Quality Monitoring Database Exposure measured period: periconceptional period | Neural tube defects |
Dorsch 198446 | Australia, Mount Gambier | Case–control study | 1951–1979 | Maternal addresses at the time of admission to hospital linked to water source Exposure measured period: samples assumed to represent exposure during pregnancy | Congenital malformation |
Ericson 198847 | Sweden | Case–control study | 1976–1977 | Earliest known maternal addresses linked to data from county environmental surveillance offices at the county councils Exposure measured period: assumed to represent exposure during pregnancy | Neural tube defects |
Holtby 201427 | Canada, Kings County, Nova Scotia | Population-based case–control study | 1988–2006 | Maternal addresses at birth linked to municipal water supply; the median of all nitrate concentration measurements taken within each municipal water supply was used as the nitrate exposure estimate for all study participants living in each municipality. Nitrate in rural private wells was estimated using geographic information system from the nitrate concentrations of monthly samples taken. The latitude and longitude of the maternal address at the time of delivery was then used to determine a nitrate-exposure estimate for each study participant Exposure measured period: not specified | Congenital malformations as a single group |
Liu 200848 | US, Connecticut | Case–control study | 2002–2004 | Maternal addresses from birth certificates linked to public drinking water data from the Connecticut Department of Public Health Exposure measured period: not specified | Birth defect, low birth weight, preterm birth |
Waller 201049 | US, Washington State | Retrospective case–control study | 1987–2006 | The distance between maternal residence and the closest stream monitor site with nitrate > 10 mg/L as NO3-N were used to estimate the risk Exposure measured period: not specified | Gastroschisis |
