Long term effects of childbearing on health.

Information on whether a woman had ever had any children was recorded for all deaths registered to ever-married women in England and Wales between 1938 and 1960. Analysis of the relation between parity and cause of death for 1.2 million women aged 45-74 years revealed that parous women had lower mortality from breast, ovarian, and endometrial cancer than did nulliparous women but a higher mortality from diabetes mellitus, gallbladder disease, cancer of the uterine cervix, nephritis and nephrosis, hypertension, ischaemic and degenerative heart disease, cerebrovascular disease, and all causes of death. There is a parallel between the long term effects of pregnancy and of oral contraceptives on health.