Persistent organic pollutants exposure during pregnancy, maternal gestational weight gain, and birth outcomes in the mother–child cohort in Crete, Greece (RHEA study)

• Concentrations of several POPs were determined in 1st trimester maternal serum.
• We examined whether in utero exposure to POPs is associated with birth outcomes.
• Birth weight was lowered by PCBs and HCB.
• Weight gain slightly influenced the association of POPs and birth weight.
• Prenatal exposure to PCBs and HCB seems to impair fetal growth.

BackgroundPersistent organic pollutants (POPs), including polychlorinated biphenyls (PCBs) and pesticides bioaccumulate through the food chain and cross the placenta. POPs are developmental toxicants in animals but the epidemiological evidence on pregnancy outcomes is inconsistent. Maternal gestational weight gain has been recently suggested as a key factor explaining the association between PCBs with lower birth weight.AimsWe examined whether in utero exposure to current low levels of different POPs is associated with fetal growth and gestational age in a mother–child cohort in Crete, Greece (Rhea study), and evaluated specifically whether maternal gestational weight gain may affect this association.MethodsWe included 1117 mothers and their newborns from the Rhea study. Mothers were interviewed and blood samples collected during the first trimester of pregnancy. Information on birth outcomes was retrieved from medical records. Concentrations of several PCBs, other organochlorine compounds (dichlorodiphenyl dichloroethene [DDE], dichlorodiphenyl trichloroethane [DDT] and hexachlorobenzene [HCB]) and one polybrominated diphenyl ether congener (tetra-bromodiphenyl ether [BDE-47]), were determined in maternal serum by triple quadrupole mass spectrometry. Multiple linear regression models were used to investigate the associations of birth weight, gestational age, and head circumference with each compound individually on the log10 scale, and with combined exposures through the development of an exposure score.ResultsIn multivariate models, birth weight was negatively associated with increasing levels of HCB (β = − 161.1 g; 95% CI: − 296.6, − 25.7) and PCBs (β = − 174.1 g; 95% CI: − 332.4, − 15.9); after further adjustment for gestational weight gain these estimates were slightly reduced (β = − 154.3 g; 95% CI: − 300.8, − 7.9 for HCB and β = − 135.7 g; 95% CI: − 315.4, 43.9 for PCBs). Furthermore, in stratified analysis, the association between POPs and birth weight was only observed in women with inadequate or excessive gestational weight gain. Small, negative associations were observed with head circumference while no association was observed with gestational age.ConclusionsThe findings suggest that prenatal exposure to PCBs and HCB impairs fetal growth and adds to the growing literature that demonstrates an association between low-level environmental pollutant exposure and fetal growth. Furthermore our results suggest that the association of POPs, maternal gestational weight gain and birth weight is probably more complex than that previously hypothesized.