Prolonged breast-feeding is an independent risk factor for postmenopausal osteoporosis

This study investigated the effects of parity and age at first pregnancy and breast-feeding, as well as duration of BF for total and per child on postmenopausal osteoporosis.

The study was conducted among 542 cases who were divided based on the presence or absence of osteoporosis. Patients were separated according to their first pregnancy and breast-feeding age as before or after 27 years. Osteoporosis was defined as a T score of -2.5 or lower.

Parity, age at first pregnancy and breast-feeding, breast-feeding period for total and average duration per child according to a questionnaire were assessed.

Osteoporosis group had significantly lower parity compared to non-osteoporosis group. The age at first pregnancy and breast-feeding<27 age were significantly more frequent in osteoporosis group. They also had prolonged breast-feeding period. Women who had a breast-feeding period per child>1 year under age 27 was higher in osteoporosis group. In multivariate analysis, women who breast-fed>1 year per child had the highest risk for osteoporosis (odds ratio: 12.92; 95% confidence interval, 3.1-52.6) and osteoporosis risk for women who breast-fed>1 year per child under age 27 was 7.1. Increased parity was associated with a significant protective effect for osteoporosis.

Extended breast-feeding period per child>1 year is the highest risk factor for osteoporosis independent of first breast-feeding age. However, high parity has a protective effect.