Long-term use of oral contraceptives, as well as certain methods of tubal ligation (TL), were linked to lower levels of antimüllerian hormone, a biomarker for ovarian aging, suggesting an increased risk for early menopause, according to preliminary research.
Using data from the Nurses’ Health Study II, researchers at the UMass Amherst School of Public Health and Health Sciences examined the association of oral contraceptive use and tubal ligation with antimüllerian hormone (AMH).
Published in the journal Menopause, the results were “intriguing,” according to lead author Christine Langton, PhD candidate.
“We’re one of the larger studies to have looked at both of these contraceptive methods at the same time,” says Langton, now a post-doctoral researcher at the National Institute of Environmental Health Sciences. “We feel we’re contributing to the story, and to the literature, though nothing we did was definitive. This is a piece of the puzzle.”
Early menopause, which occurs before 45, puts women at greater risk for a range of health conditions including cardiovascular disease, osteoporosis and dementia. The researchers noted that oral contraceptives change hormone levels and prevent ovulation; tubal ligation may affect blood supply to the ovaries, and certain methods of the procedure may damage the ovary and surrounding neural tissue.
“Recently, AMH has become an established marker for the timing of menopause and was found to be strongly associated with the risk of early menopause,” the authors wrote. “Yet, the association of reproductive and lifestyle factors with AMH levels remains unclear.”
The team focused on a subset of 1420 premenopausal women in the Nurses’ Health Study prospective cohort who had provided a blood sample between 1996 and 1999. A history of their oral contraceptive use and tubal ligation began in 1989 and was updated every two years until their blood was collected.
“Women who reported that their [tubal ligation] procedure included the use of a clip, ring or band had significantly lower AMH levels compared to women who never had a TL procedure,” the researchers wrote.
One limitation is the small number of women reporting the type of tubal ligation, Langton added.
When it came to oral contraceptives, “we saw a significant inverse association – the longer the use of oral contraceptives, the lower the AMH levels were,” Langton said. “That particular finding was a little surprising to us because it didn’t completely align with what we saw when we looked at oral contraceptives and early menopause in the larger cohort” of more than 115,000 women.
Even after adjusting for factors including BMI, smoking, alcohol, number of pregnancies and breastfeeding, the inverse association between oral contraceptive use and AMH levels remained significant.
“We think further research is warranted,” Langton said.
Source: University of Massachusetts
