Reproductive factors and their associations with osteoporosis and osteoarthritis in women
Wei, S (2012) Reproductive factors and their associations with osteoporosis and osteoarthritis in women. PhD thesis, University of Tasmania.
Women are at higher risk of both osteoporosis and osteoarthritis (OA) compared
with age-matched males. Sex hormones and reproductive factors may partly explain these
differences. This study therefore aimed to investigate reproductive factors including parity,
menstrual regularity, use of oral contraceptives (OC) and hormone replacement therapy
(HRT) and their associations with bone mass, cartilage and radiographic OA in populationbased
samples of both young and older women.
Young women aged 26 to 36 years were selected from the Childhood Determinants
of Adult Health (CDAH) study, a 20-year follow-up of children who participated in 1985
Australian Schools Health and Fitness Survey (ASHFS). Older women aged 50 to 80 years
were selected from the Tasmanian Older Adult Cohort (TASOAC) study, an ongoing
prospective study in southern Tasmania. Parity, menstrual regularity and use of OC and
HRT were assessed by self-administered questionnaire. Bone mass was measured by
quantitative ultrasound (QUS) for young women and bone mineral density (BMD) by dualenergy
x-ray absorptiometry (DXA) for older women. Knee cartilage volume and cartilage
defects were measured by magnetic resonance imaging (MRI) for both young and older
women and radiographic OA was assessed by X-ray only for older women.
Key findings were:
• Young women:
o Current use of OC was associated with higher bone mass.
o Irregular menstrual cycles were associated with higher bone mass and the
association was partially mediated by markers of androgen status especially
o Parity was positively associated with cartilage defects primarily at the
patella site. Women with three or more children had the highest prevalence
of cartilage defects. • In older women:
o Ever use and duration of OC use were associated with higher BMD in the
spine and total body measured at age 50-80 years.
o OC use for five to ten years was associated with a reduction of vertebral
o Parity was associated with lower cartilage volume primarily in the tibial
compartment and the associations were dose-dependent.
o Parity was associated with higher cartilage defects only in the patella
o There were no associations between parity and osteophytes or joint space
o Use of OC and HRT was not associated with knee cartilage volume,
cartilage defects or radiographic OA including JSN and osteophytes.
In conclusion, these cross-sectional analyses of population-based samples of both
young and older women showed use of OC was associated with higher bone mass
suggesting a protective effect of OC use on bone health. In young women, menstrual
irregularity was associated with alterations of sex hormones but may not be as harmful for
bone mass as previously believed. Parity, particularly higher parity, was associated with
higher cartilage defects in young women and low cartilage volume in older women
indicating an effect of childbearing on the development of OA in women. Adiagram below
illustrated the main conclusions from this study.
|Item Type:||Thesis (PhD)|
|Additional Information:||Copyright the Author|
|Keywords:||use of oral contraceptives, parity, menstrual irregularity, bone mass, cartilage volume, cartilage defects|
|Deposited By:||ePrints Officer|
|Deposited On:||17 Aug 2012 14:33|
|Last Modified:||16 Oct 2013 15:35|
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