Urine samples were collected between 22 and 29 gestational weeks. Women were asked to collect the first morning urine at home before the hospital study visit. If forgotten, the urine sample was collected at the hospital during the prenatal study visit. Urine samples were aliquoted and stored at −80°C. Measurements of 2,4- and 2,5-dichlorophenol, bisphenol A, benzophenone-3, triclosan, methyl-, ethyl-, propyl-, and butylparabens,20 (link) and creatinine were performed at the Centers for Disease Control and Prevention (CDC) in Atlanta, GA. Depending on the phenol biomarkers, the coefficients of variation of about 60 replicates in a period of 9 months were between 3% and 10% at concentrations ranging from around 2 to 70 ng/ml. Total paraben concentration (∑PB) was calculated by summing molar concentrations of the 4 parabens.
Sample shipments to CDC and phenol measurements were performed during 2 periods. Among the 191 male newborns in our previous study that assessed the associations of phenols with male genital anomalies and birth outcomes (weight, height, head circumference),15 (link),21 (link) 110 matched the inclusion criteria of the present study and were considered here. Their urine samples were analyzed for phenols in 2008. In 2011, we extended phenol measurements to the remaining 410 women matching the inclusion criteria (eFigure 1, http://links.lww.com/EDE/A801). Year of analysis was taken into account in statistical analyses (see below). The laboratory used the same analytic methodology to analyze all samples.