ABSTRACT
To examine the relationship between oral contraceptive (OC) use and bone mineral density (BMD), we conducted a cross-sectional study on 352 white, nonsmoking, perimenopausal women aged 40-54 years. We measured bone mineral density of lumbar vertebrae 2-4 with dual photon absorptiometry and mid-radius and distal radius with single photon absorptiometry. After controlling for age, body mass, current physical activity, current calcium intake and history of breastfeeding, our analysis did not find substantial differences in BMD at any site between OC ever users and never users. However, OC ever users had slightly higher lumbar BMD among premenopausal women. No significant association was identified between recency of OC use and BMD. The results of our study suggest that when other factors are accounted for, OC use is not strongly associated with BMD among perimenopausal women, although we cannot exclude a slight beneficial effect.
PIP: This document reports the findings of a cross-sectional study in which the relationship between oral contraceptive (OC) use and bone mineral density (BMD) was examined. In postmenopausal women the loss of bone density and mass is well documented. This situation, if left unchecked, could lead to osteoporosis, and the financial impact on the U.S. public health system could range from $2 to $6.1 billion per year. This study controlled for the variables of age, body mass, current physical activity, current calcium intake, and history of breast feeding, all of which affect BMD. Of the 352 women in the study, 7 currently used OCs, 92 women had never used OCs, and 253 women were former OC users. These women were subdivided into 2 groups based on OC usage. These were the never users group and the ever users group. Bone mineral density was measured using dual photon absorptionmetry (Norland Duel 2600) on the 2nd, 3rd, and 4th lumbar vertebrae and single photon absorptionmetry on the midradius and distal radius (5-mm site). Separate analyses were conducted for premenopausal and postmenopausal women. It was found that in the premenopausal group, with increasing OC involvement, that the BMD increased slightly but was not considered statistically significant (P = 0.21). After adjusting for the variables of age, breastfeeding, body mass, physical activity, and calcium intake, no dose-effect relationship could be found between premenopausal and postmenopausal women. Women considered recent OC users were associated with an increase in BMD, though overall this was not statistically significant. The results of this study suggest that when variables are statistically adjusted for OC use is not strongly associated with BMD in perimenopausal women.
