Oral contraception and congenital abnormalities.

Of 10 479 single births in South Glamorgan between January 1974 and June 1976, 27.3 per cent of infants were born to women who had used oral contraception in the three months prior to their last menstrual period (users) and 72.3 per cent were born to women who had not used oral contraception during the same period (non users). There were significantly more infants with neural tube defects among users compared with non users. Abnormalities of the digestive, genito-urinary and cardiovascular system, bones, muscle, skin and connective tissues, endocrine glands, blood chromosomes and oral clefts, were of similar incidence in the two groups.