Breastfeeding, pregnancy associated with reduced risk for early menopause
Parity and breastfeeding are each independently associated with a significantly lower risk for early natural menopause, according to an analysis of the Nurses’ Health Study II cohort.
“Compared with women who were never pregnant or had a pregnancy lasting less than 6 months, women who had two pregnancies lasting at least 6 months had a 16% lower risk for early natural menopause, and women with three pregnancies had a 22% lower risk,” Christine Langton, MSW, MPH, a doctoral student at the University of Massachusetts Amherst School of Public Health and Health Sciences, told Healio. “Women who breastfed had an even lower risk for early natural menopause. Those who breastfed for 25 months or more during their premenopausal years had a 26% lower risk than women who breastfed for less than 1 month. Women with three or more pregnancies who breastfed exclusively for a total of 7 to 12 months had a 32% lower risk of early menopause compared with women with the same number of children who breastfed exclusively for less than 1 month.”
In a population-based study, Langton and colleagues analyzed data from 108,887 premenopausal women participating in the Nurses’ Health Study II cohort (1989-2015) and aged 25 to 42 years at baseline (mean age at baseline, 34 years; 93.9% white). Follow-up continued until menopause, age 45 years, hysterectomy, oophorectomy, death, cancer diagnosis, loss to follow-up or May 2015. Researchers assessed parity at baseline and every 2 years. History and duration of total and exclusive breastfeeding were assessed three times during follow-up. Menopause status and age were assessed every 2 years. Primary outcome was the risk for natural menopause before age 45 years.
Compared with nulliparous women, those reporting one, two, three and four or more pregnancies lasting at least 6 months had HRs for early menopause of 0.92 (95% CI, 0.79-1.06), 0.84 (95% CI, 0.73-0.96), 0.78 (95% CI, 0.67-0.92), and 0.81 (95% CI, 0.66-1.01), respectively.
In models adjusted for parity, HRs for duration of exclusive breastfeeding of 1 to 6, 7 to 12, 13 to 18, and 19 or more months were 0.95 (95% CI, 0.85-1.07), 0.72 (95% CI, 0.62-0.83), 0.8 (95% CI, 0.66-0.97) and 0.89 (95% CI, 0.69-1.16), respectively, compared with less than 1 month of exclusive breastfeeding.
“Despite the significant test for trend, estimates were not observed to be lower as duration of exclusive breastfeeding increased,” the researchers wrote.
In analyses restricted to parous women, risk for early menopause was lowest among those reporting exclusive breastfeeding for 7 to 12 months in each level of parity. The HR was 0.79 for women reporting two pregnancies and 7 to 12 months of breastfeeding (95% CI, 0.66-0.96) and 0.68 for women reporting at least three pregnancies and 7 to 12 months of breastfeeding (95% CI, 0.52-0.88).
The researchers noted that breastfeeding at levels consistent with current recommendations may confer an additional benefit of lower risk for early menopause.
“It is important to note that since our study was an epidemiologic study and we only observed associations between pregnancy, breastfeeding and early menopause, we are not suggesting that these reproductive factors cause menopause timing,” Langton said. “However, we did observe that women who had more pregnancies and longer duration of breastfeeding, particularly exclusive breastfeeding, experienced lower risk for early menopause compared with women who were never pregnant or breastfed for less than 1 month. That doesn’t mean that every nulliparous woman will experience early menopause. There are many factors that determine menopause timing, including genetic and lifestyle factors.” – by Regina Schaffer
For more information:
Christine Langton, MSW, MPH, can be reached at the School of Public Health Sciences, Department of Biostatistics and Epidemiology, University of Massachusetts, 715 N. Pleasant St., Amherst, MA 01003; email: email@example.com.
Disclosures: The NIH, HHS and the Eunice Kennedy Shriver National Institutes of Child Health and Human Development supported this study. The authors report no relevant financial disclosures.