Associations of reproductive factors with postmenopausal follicle stimulating hormone.

Purpose: Recent studies have suggested that higher postmenopausal follicle stimulating hormone (FSH) may be associated with lower risk of diabetes. However, relatively little is known about postmenopausal FSH levels, including the level of variation between women and whether reproductive factors are associated with this variation.

Methods: We assessed the relationship of multiple reproductive factors with FSH levels among 588 postmenopausal women in the Kuopio Ischaemic Heart Disease Risk Factor Study. Participants were aged 53 to 73 years and not using hormone therapy at study enrollment (1998-2001) when reproductive factors were assessed and FSH was measured.

Results: After adjustment for age, menopause timing, sex steroid levels, adiposity and behavioral factors, we observed numbers of pregnancies and age at first birth were each inversely associated with FSH levels. For example, women with ≥ 3 births and an age at first birth ≥ 25 years had mean FSH levels that were 7.8 IU/L lower than those of women with 1-2 births and an age at first birth ≤ 24 years (P = 0.003). Number of miscarriages was inversely associated with FSH levels (-2.7 IU/L per miscarriage; P = 0.02). Women reporting 4 or more years of past hormone therapy use had significantly higher mean FSH levels than women who had never used hormone therapy (P for trend = 0.006).

Conclusion: Multiple reproductive factors were associated with postmenopausal FSH, independent of estradiol, adiposity and other confounders. These findings warrant replication and further exploration of potential underlying mechanism.