In Reply We agree that the relevant question for women would be “how long should I delay conception after an operation?” rather than “how long should I delay birth after an operation?” However, the use of an operation-to-birth interval vs an operation-to-last-menstrual-period interval should not appreciably change risk estimates from the data obtained in this study. Furthermore, the date of birth is ascertained with considerably more accuracy from state birth records than date of last menstrual period.