Context: Prenatal androgen excess can cause a phenocopy of polycystic ovary syndrome (PCOS) in mammals. Retrospective studies have suggested that girls at risk for PCOS have low birth weight, and prospective studies have suggested an increased prevalence of small-for-gestational-age offspring in women with PCOS. Objective: The objective of the study was to determine whether infants of women with PCOS have reduced birth weight or increased intrauterine androgen levels. Design: This was a prospective case-control study. Participants: Thirty-nine PCOS and 31 control women and their infants participated in the study. Main Outcome Measures: Birth weight and mixed cord blood testosterone, androstenedione (A), dehydroepiandrosterone, 17-hydroxyprogesterone, estradiol (E2), and dihydrotestosterone levels were measured. Results: Mean birth weight did not differ, but there was a significant increase in the prevalence of large-for-gestational-age infants in the PCOS group. Cord blood E2 and A levels were lower (P < 0.05), but testosterone to E2 ratios did not differ in female PCOS compared with control offspring. There was no difference in E2 and A levels in the male PCOS and control offspring. There was no difference in 17-hydroxyprogesterone or other androgen levels in either male or female PCOS offspring compared with their respective control group. Conclusion: Infants of women with PCOS were more likely to be large for gestational age. Female offspring of affected women have lower cord blood A levels; other cord blood androgen levels do not differ compared with female control offspring. Cord blood E2 levels are also significantly decreased in PCOS, without any difference in the testosterone to E2 ratio, suggesting decreased fetal or placental production of steroids.