Postnatal weight growth and trihalomethane exposure during pregnancy

Impaired postnatal growth after chloroform exposure in utero has been observed in rodents without an effect on birth weight. We aimed to study the relationship between exposure to trihalomethanes (THMs) during pregnancy and postnatal weight growth during infancy.

We analysed 2216 mother-child pairs recruited in Gipuzkoa, Sabadell, Valencia (Spain, INMA Project, enrollment: 2003-2008) and Crete (Greece, RHEA Study, enrollment: 2007-2008). Drinking water habits and water-related activities ascertained through personal interviews were combined with THM measurements in drinking water to estimate THM exposure through different exposure routes during pregnancy. Weight measurements during the first year of life were used to fit postnatal weight growth curves from birth to one year and to predict weight at six months. Multiple linear regression was used to evaluate the relationship between six months weight gain and interquartile range (IQR) increase in THM exposure adjusting for confounders.

Average weight gain at six months ranged from 4325 g (Gipuzkoa) to 4668 g (Crete). Median residential THM levels ranged from 1 μg/l (Crete) to 117 μg/l (Sabadell). No significant association was observed overall (-24.4 g [95% CI -78.8, 30.0] for an IQR increase in total residential uptake). A negative relationship was observed in Sabadell (-148 g [95% CI -282, -13.7]) for an IQR increase in ingestion THM uptake.

No consistent evidence of an association between THM exposure during pregnancy and postnatal growth was observed. The novelty of the hypothesis and the negative trend observed in the region with the highest levels warrants the replication in future studies.