Association of Parity and Breastfeeding With Risk of Early Natural Menopause

Abstract

IMPORTANCE Pregnancy and breastfeeding prevent ovulation and may slow the depletion of the ovarian follicle pool. These factors may lower the risk of early menopause, a condition associated with increased risk of cardiovascular disease and other adverse health outcomes. OBJECTIVE To examine the association of parity and breastfeeding with the risk of early menopause. DESIGN, SETTING, AND PARTICIPANTS This population-based cohort study within the Nurses' Health Study II cohort (1989-2015) included premenopausal participants who were aged 25 to 42 years at baseline. Response rates were 85% to 90% for each cycle, and follow-up continued until menopause, age 45 years, hysterectomy, oophorectomy, death, cancer diagnosis, loss to follow-up, or end of follow-up in May 2015. Hypotheses were formulated after data collection. Data analysis took place from February to July 2019. EXPOSURES Parity (ie, number of pregnancies lasting Ն6 months) was measured at baseline and every 2 years. History and duration of total and exclusive breastfeeding were assessed 3 times during follow-up. Menopause status and age were assessed every 2 years. MAIN OUTCOMES AND MEASURES Risk of natural menopause before age 45 years. RESULTS At baseline, 108 887 premenopausal women aged 25 to 42 years (mean [SD] age, 34.1 [4.6] years; 102 246 [93.9%] non-Hispanic white) were included in the study. In multivariable models, higher parity was associated with lower risk of early menopause. Hazard ratios were attenuated with adjustment for breastfeeding but remained significant. Compared with nulliparous women, those reporting 1, 2, 3, and 4 or more pregnancies lasting at least 6 months had hazard ratios 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 (P for trend = .006). In multivariable models also adjusted for parity, hazard ratios 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), 0.80 (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 (P for trend = .001). Despite the significant test for trend, estimates were not observed to be lower as duration of exclusive breastfeeding increased. In a stratified analysis of parous women, risk of early menopause was lowest among those reporting exclusive breastfeeding for 7 to 12 months in each level of parity (women with 2 pregnancies and 7-12 months of breastfeeding: HR, 0.79; 95% CI, 0.66-0.96; Ն3 pregnancies and 7-12 months of breastfeeding: HR,

Factors influencing age at natural menopause

“…In a prospective cohort study that included 108 887 women, risk of early menopause was lowest among those reporting exclusive breastfeeding during their premenopausal years for 7–12 months. It was reported that breastfeeding was also associated with a significantly lower risk of early menopause independent of parity 14 . In our study, duration of breastfeeding weakly correlated with age at natural menopause.…”

“…The association of parity with the timing of menopause has been previously examined in the literature. Lower parity and nulliparity was associated with higher risk of early menopause 9,13,14 . In our study, the mean age at menopause was found significantly higher in those reporting five or more births than P0 and P1‐4 groups.…”

Study of Factors Associated with the Age of Natural Menopause in Menopausal Women Aged 30 to 80 Years from the Keur Massar Health District in 2015 (Senegal)

“…Faye et al found similar results in Burkina Faso [12], as did Garrido-Latorre in Mexico [19] and Kaczmarek in Poland [10]. Christine et al in her multivariate model also found higher parity associated with a lower risk of early menopause [21]. The number of children per woman can influence the age of menopause.…”

Prevalence and Risk Factors of Premature Ovarian Insufficiency/Early Menopause

“…43 Consistent with this, a lower risk of early menopause was associated with longer breastfeeding durations of 7 to 12 months (multiadjusted HR: 0.72; 95% CI: 0.62, 0.83) or 13 to 18 months (multiadjusted HR: 0.80; 95% CI; 0.66, 0.97), compared with less than 1 month of exclusive breastfeeding in the Nurses' Health Study II (NHS II) cohort. 44 Parenting/Childhood Experiences Lower cognitive scores in childhood were associated with earlier age at menopause and childhood intelligence was correlated with age at natural menopause. 43,45,46 Early-life violence may affect reproductive aging as demonstrated by the Avon Longitudinal Study of parents and children which found earlier age at menopause in victims of sexual abuse.…”

“…43 Consistent with this, a lower risk of early menopause was associated with longer breastfeeding durations of 7 to 12 months (multiadjusted HR: 0.72; 95% CI: 0.62, 0.83) or 13 to 18 months (multiadjusted HR: 0.80; 95% CI; 0.66, 0.97), compared with less than 1 month of exclusive breastfeeding in the Nurses' Health Study II (NHS II) cohort. 44…”