“…32,33 All analyses were adjusted for age (continuous variable). We also examined the following potential confounding factors: zygosity (monozygotic, dizygotic), 41 social class (blue collar, intermediate, white collar), 42 age at birth of first child (Ͻ25, Ն25 years), 36 number of children (0, 1-2, Ն3), 36 use of oral contraceptives (never, ever), 36 body mass index (Ͻ25, 25-29, Ն30 kg/m 2 ), 40 alcohol use (0, 1-399, Ն400 g/month), 43 smoking (never smoker, occasional smoker, ex-smoker, current smoker) 44 and physical activity in leisure time (sedentary, occasional, conditioning exerciser).…”