Tubal ligation and the risk of vertebral fractures.

Osteoporosis is a major public problem. More than 35 million Americans are at risk of developing osteoporosis. Nearly half of all women will have an osteoporotic fracture in their lifetime. Tubal ligation (tubal sterilization) is used more than any other single method of contraception in the USA and worldwide. In 1995, 34.6% (approximately 7 million) of ever-married US women between ages 35-44 years had undergone tubal ligation. Tubal sterilization may disturb ovarian function and be associated with more menstrual and menopausal symptoms and, thus, may be a risk factor for osteoporosis. The objective of this paper is to examine the possible association between tubal sterilization and osteoporotic fractures. Data are from a questionnaire mailed to a previously identified cohort of college/university alumnae who had graduated between 1926 and 1981. This study was performed during 1996 and 1997, 15 years after the initial study. The subjects were 3,940 women participants in the follow-up study. Their mean age was 53.7 years at time of reporting, ranging from 37 to over 80 years. Excluding deaths and non-deliverables the response rate was 85%. Of the 3,940 subjects, 491 (12.5%), and, of the ever-pregnant women, 15.5%, had undergone tubal sterilization (TS); 899 (22.8%) reported at least one fracture after age 20, and 70 (1.8%) at least one vertebral fracture after age 20, which had been confirmed by X-ray. TS was strongly associated with self-reports of vertebral fractures that had been confirmed by X-ray. The multivariable adjusted odds ratios and 95% confidence intervals for women 50 years and over and for women 55 years and over were, respectively, 2.7 (1.4, 5.0) and 3.3 (1.5, 7.0). Having had any fracture was not significantly associated with TS: odds ratio (OR) = 1.1 for women 50 years and older and OR = 1.3 for those 55 years and older. This epidemiological study in a cohort of highly educated, mostly Caucasian women shows an association between past tubal sterilization and self-reported X-ray-confirmed vertebral fractures. These results need to be confirmed in other cohorts--the pathophysiology of this association is worthy of further study.