BACKGROUND: Prenatal perfluorooctanoate (PFOA) exposure has been associated with reduced birth weight but maternal glomerular filtration rate (GFR) may attenuate this association. Further, this association remains unclear for other perfluoroalkyl substances (PFAS), such as perfluorooctane sulfonate (PFOS), perfluorohexane sulfonate (PFHxS), and perfluorononanoate (PFNA). We estimated associations between prenatal PFAS exposure and birth outcomes, and the influence of GFR, in a Spanish birth cohort. METHODS: We measured PFHxS, PFOS, PFOA, and PFNA in 1st-trimester maternal plasma (years: 2003-2008) in 1202 mother-child pairs. Continuous birth outcomes included standardized weight, length, head circumference, and gestational age. Binary outcomes included low birth weight (LBW), small-for-gestational-age, and preterm birth. We calculated maternal GFR from plasma-creatinine measurements in the 1st-trimester of pregnancy (n=765) using the Cockcroft-Gault formula. We used mixed-effects linear and logistic models with region of residence as random effect and adjustment for maternal age, parity, pre-pregnancy BMI, and fish intake during pregnancy. RESULTS: Newborns in this study weighted on average 3263g and had a median gestational age of 39.8weeks. The most abundant PFAS were PFOS and PFOA (median: 6.05 and 2.35ng/mL, respectively). Overall, PFAS concentrations were not significantly associated to birth outcomes. PFOA, PFHxS, and PFNA showed weak, non-statistically significant associations with reduced birth weights ranging from 8.6g to 10.3g per doubling of exposure. Higher PFOS exposure was associated with an OR of 1.90 (95% CI: 0.98, 3.68) for LBW (similar in births-at-term) in boys. Maternal GFR did not confound the associations. CONCLUSIONS: In this study, PFAS showed little association with birth outcomes. Higher PFHxS, PFOA, and PFNA concentrations were non-significantly associated with reduced birth weight. The association between PFOS and LBW seemed to be sex-specific. Finally, maternal GFR measured early during pregnancy had little influence on the estimated associations.

This study was funded by grants from the European Union (FP7-ENV-2011 cod 282957 and HEALTH.2010.2.4.5-1), and from Spain: Instituto de Salud Carlos III, Ministry of Health CIBERESP, the Conselleria de Sanitat, Generalitat Valenciana, (Red INMA G03/176; CB06/02/0041; PI041436, PI081151, PI06/0867, PS09/00090, PI13/02187; FIS-FEDER: PI03/1615, PI04/1509, PI04/1112, PI04/1931, PI05/1079, PI05/1052, PI06/1213, PI07/0314, PI09/02647, PI11/01007, PI11/02591, PI11/ 02038, PI12/01890, PI13/1944, PI13/2032, PI14/00891, and PI14/1687; pre-doctoral grant PFIS - FI14/00099 and; Miguel Servet-FEDER: CP11/0178 and CPII16/00051), Department of Health of the Basque Government (2005111093 and 2009111069); the Provincial Government of Gipuzkoa (DFG06/004 and DFG08/001); and the Generalitat de Catalunya-CIRIT (1999SGR 00241)