Secondary sex ratio among women exposed to diethylstilbestrol in utero.
BACKGROUND
Diethylstilbestrol (DES), a synthetic estrogen widely prescribed to pregnant women during the mid-1900s, is a potent endocrine disruptor. Previous studies have suggested an association between endocrine-disrupting compounds and secondary sex ratio.


METHODS
Data were provided by women participating in the National Cancer Institute (NCI) DES Combined Cohort Study. We used generalized estimating equations to estimate odds ratios (ORs) and 95% confidence intervals (CIs) for the relation of in utero DES exposure to sex ratio (proportion of male births). Models were adjusted for maternal age, child's birth year, parity, and cohort, and accounted for clustering among women with multiple pregnancies.


RESULTS
The OR for having a male birth comparing DES-exposed to unexposed women was 1.05 (95% CI, 0.95-1.17). For exposed women with complete data on cumulative DES dose and timing (33%), those first exposed to DES earlier in gestation and to higher doses had the highest odds of having a male birth. The ORs were 0.91 (95% C, 0.65-1.27) for first exposure at > or = 13 weeks gestation to < 5 g DES; 0.95 (95% CI, 0.71-1.27) for first exposure at > or = 13 weeks to > or = 5 g; 1.16 (95% CI, 0.96-1.41) for first exposure at < 13 weeks to < 5 g; and 1.24 (95% CI, 1.04-1.48) for first exposure at < 13 weeks to > or = 5 g compared with no exposure. Results did not vary appreciably by maternal age, parity, cohort, or infertility history.


CONCLUSIONS
Overall, no association was observed between in utero DES exposure and secondary sex ratio, but a significant increase in the proportion of male births was found among women first exposed to DES earlier in gestation and to a higher cumulative dose.
Wise
Lauren A
LA
Slone Epidemiology Center, Boston University, Boston, Massachusetts 02215, USA. lwise@slone.bu.edu
Palmer
Julie R
JR
Hatch
Elizabeth E
EE
Troisi
Rebecca
R
Titus-Ernstoff
Linda
L
Herbst
Arthur L
AL
Kaufman
Raymond
R
Noller
Kenneth L
KL
Hoover
Robert N
RN
D000328:Adult; D004054:Diethylstilbestrol / Q000633:toxicity*; D052244:Endocrine Disruptors / Q000633:toxicity*; D004968:Estrogens, Non-Steroidal / Q000633:toxicity*; D005260:Female; D006801:Humans; D007231:Infant, Newborn; D008297:Male; D008431:Maternal-Fetal Exchange; D011247:Pregnancy; D012744:Sex Ratio