Oral contraceptives and bone mineral density: A population-based study.
OBJECTIVE
We sought to test the hypothesis that exposure to oral contraceptives protects the skeleton.


METHODS
Multiple regression techniques were used to analyze data for a random sample of 710 Australian women (age range, 20-69 years). Bone mineral density was measured at the lumbar spine, proximal femur, whole body, and distal forearm. Oral contraceptive exposure was assessed by a questionnaire.


RESULTS
Women exposed to oral contraceptives had a 3.3% greater mean bone mineral density adjusted for body mass index and age at the lumbar spine (partial r (2) = 0.009; P =.014). Adjusted mean vertebral bone mineral density was 3.3% greater for premenopausal women (partial r (2) = 0.008; P <.05), but the effect did not reach significance among postmenopausal women. Higher bone mineral density was associated with increased duration of exposure, with a mean increase of 3.2% associated with the first 5 years and a further 0.2% with >/=5 years of exposure. No association was detected at other sites.


CONCLUSIONS
Exposure to oral contraceptives may be associated with higher lumbar spine bone mineral density.
Pasco
J A
JA
Department of Medicine, St Vincent's and The Geelong Hospitals, the University of Melbourne, Geelong, Victoria, Australia.
Kotowicz
M A
MA
Henry
M J
MJ
Panahi
S
S
Seeman
E
E
Nicholson
G C
GC
D015502:Absorptiometry, Photon; D000328:Adult; D000367:Age Factors; D000368:Aged; D000428:Alcohol Drinking; D001315:Australia / Q000453:epidemiology; D015992:Body Mass Index; D015519:Bone Density / Q000187:drug effects*; D001862:Bone Resorption / Q000453:epidemiology / Q000517:prevention & control*; D001842:Bone and Bones / Q000187:drug effects / Q000502:physiology*; D002136:Calcium, Dietary; D003276:Contraceptives, Oral / Q000494:pharmacology* / Q000627:therapeutic use; D005260:Female; D005269:Femur / Q000187:drug effects / Q000502:physiology; D005542:Forearm / Q000502:physiology; D006801:Humans; D008159:Lumbar Vertebrae / Q000187:drug effects / Q000502:physiology; D008593:Menopause / Q000502:physiology; D008875:Middle Aged; D015999:Multivariate Analysis; D012044:Regression Analysis; D012907:Smoking; D011795:Surveys and Questionnaires
D002136:Calcium, Dietary; D003276:Contraceptives, Oral