Influence of parity and lactation on hip fracture risk

Several studies indicate that parity and lactation are associated with mode st, short-term bone loss, but the long-term effect on osteoporotic fracture risk is uncertain. The authors therefore analyzed data from a population-b ased case-control study among Swedish postmenopausal women aged 50-81 years between October 1993 and February 1995. Mailed questionnaires and telephon e interviews were used to collect data on 1,328 incident cases with hip fra cture and 3,312 randomly selected controls. in age-adjusted analyses, the r isk of hip fracture among all women was reduced by 10% per child (95% confi dence interval (CI): 5, 14). After multivariate adjustment including body m ass index as a covariate, the risk reduction was 5% per child (95% CI: 0, 1 0). Oral contraceptive use modified the association of parity with hip frac ture risk. Among never users of oral contraceptives, the risk of hip fractu re was reduced by 8% per child (95% CI: 2, 13), whereas among ever users of oral contraceptives, the risk was in the opposite direction, with an incre ase in risk by 19% per child (95% CI: 0, 41). After parity was considered, there was no association of duration of lactation period with fracture risk . The authors conclude that parity is modestly associated with a reduced hi p fracture risk among women who had not used oral contraceptives previously .