The contribution of childbearing to the sex difference in first admission rates for affective psychosis.

This epidemiological study examines the contribution of childbearing to the sex difference in first admission rates for affective psychosis. The effects of sex, age, marital status and parity on first admission rates are examined in 114 patients admitted from a defined catchment area. The rate of first admission in females is almost twice that in males. Using logistic regression analysis one significant factor accounting for this sex difference emerges: female parity. The effect of parity is evident up to the age of 54, and it entirely accounts for the sex difference in relative risk. Nonparous females have a lower relative risk of admission than males. An apparent effect of marital status is only significant in females, and is accounted for by parity and age.