"Prolonged pregnancy" after oral contraceptive therapy.

A prospective study of 151 patients whose last menstrual period was an oral contraceptive induced haemorrhage indicated that, in many, ovulation was considerably delayed and that the calculated due date of delivery was therefore erroneous; prolonged pregnancy (more than 42 weeks gestation) occurred in 37.4% and, in 9%, gestation exceed 44 weeks.