ORAL CONTRACEPTION AND OTHER FACTORS IN RELATION TO HOSPITAL REFERRALFOR FRACTURE - FINDINGS IN A LARGE COHORT STUDY

There is good evidence that estrogens and progestogens have an importa nt effect on bone metabolism. This article explores the relationship b etween oral contraceptive (OC) use and fractures occurring at various sites among the 17,032 participants in the Oxford-Family Planning Asso ciation contraceptive study, which now includes information accumulate d during 310,000 woman-years of observation between 1968 and 1994. In total, 1308 women suffered at least one fracture during the follow-up period, which was largely confined to premenopausal years. When all fr actures were combined, there was a modest, but highly significant tren d (p < 0.001) of increasing risk with total duration of oral contracep tive use. In addition, there was statistically significant heterogenei ty (p < 0.01) when overall fracture rates were examined in relation to recency of oral contraceptive use during the premenopausal lifespan. The highest relative risk (1.3, 95% CI 1.1-1.5) was for current or rec ent oral contraceptive users; however, viewed as a whole, no clear pat tern of risk was apparent. Examination of the data for individual frac ture sites (including the lower end of the radius/ulna) did not provid e any evidence of a protective effect of oral contraceptive use. These results are closely similar to those reported from the Royal College of General Practitioners Oral Contraception Study in 1993. CONTRACEPTI ON 1998;57:231-235 (C) 1998 Elsevier Science Inc. All rights reserved.