Contraceptives and the conceptus. II. Sex of the fetus and neonate after oral contraceptive use.

The sex distribution of 1421 induced abortuses and 2986 newborn infants was correlated with maternal contraceptive histories. Sex of abortuses was determined by chromosome and sex chromatin analyses. No statistically significant differences (P Greater Than 10) were found between the sex ratios either of the fetuses or of the infants of women who used hormonal (oral) contraceptives as compared to those of noncontraceptive controls nor between the induced and newborn series. Also, no correlation was found between sex of the conceptus and total duration of oral contraceptive use, or interval between termination of contraceptive use and conception. Therefore, if the use of low dose oral hormonal contraceptives has an effect on the sex of subsequent offspring, it is likely to be small since the 95% confidence interval for the sex ratios for the oral contraceptive groups divided by the sex ratios of the noncontraceptive group (odds ratio) are 0.80 to 1.22 for induced abortions, and 0.82 to 1.10 for newborns. These conclusions are not in agreement with some earlier reports, generally of small samples, but they are consistent with the results of Rothman and Liess (1976) from a sample of 6109 infants born to oral contraceptive users.