Early Menstruation Linked to Increase in Hot Flashes, Night Sweats Later in Life

July 23, 2020

A pooled analysis of 6 studies is shedding light on the relationship between early age at menarche and incidence of vasomotor menopausal symptoms.

New data from the Life course Approach to reproductive health and Chronic disease Events (InterLACE) international collaboration suggests menstruation at 11 years of age or younger was linked to an increased risk of hot flashes and night sweats later in life.

Results of the analysis indicated early age at menarche was a risk factor for vasomotor menopausal symptoms later in life, but investigators noted midlife body mass index (BMI) appeared to be have a major role in modifying this risk.

"Women who experienced early menstruation and were overweight or obese in midlife had a two times greater risk of frequent hot flushes and night sweats, compared with women who experienced their first period aged 14 years or older, and had normal weight," said Gita Mishra, PhD, professor at the University of Queensland and InterLACE project leader, in a statement. "These findings encourage women with early menstruation to engage in health promotion programs, especially weight management in adulthood.”

To further explore potential associations between age at menarche and risk of vasomotor menopausal symptoms and whether BMI influenced this association, Mishra and colleagues designed the current study as a pooled analysis of 6 cohort studies within InterLACE. The 6 studies used in the current study included the Australian Longitudinal Study on Women’s Health, the Healthy Ageing of Women Study, the MRC National Survey of Health and Development, the National Child Development Study, the Study of Women’s Health Across the Nation, and the Seattle Midlife Women’s Health Study.

From these 6 studies, investigators identified a cohort of 18,555 women for inclusion in their study. The median age of women included in the analysis was 48 years, the mean age at menarche was 12.8 years, and 19.1% of women reported experiencing menarche at 11 years or earlier. Of note, 29% of women were overweight and 21% were considered obese.

Using information from these studies, investigators obtained patient-level data related to VMS frequency for 13,602 patients and symptom severity data for 4953 patients.

The primary outcomes of interest for the analysis were hot flashes and night sweats. For the purpose of comparison, frequency was classified as never, rarely, sometimes, and often. Severity was classified as never, mild, moderate, or severe.

Investigators used multinomial logistic regression models to estimate relative risk ratios. Analyses were adjusted for multiple confounders including BMI, birth year, race/ethnicity/region, education level, and smoking status.

Upon analysis, investigators found menarche at 11 years or younger were more likely to report hot flashes (RRR, 1.48; 95% CI, 1.24-1.76) and night sweats (RRR, 1.59; 95% CI, 1.49-1.70) often compared to those with menarche at 14 years or later. When examining severity, investigators found menarche at 11 years or younger was associated with increased risk of reporting severe hot flashes (RRR, 1.16; 95% CI, 0.94-1.42) and night sweats (RRR, 1.27; 95% CI, 1.01-1.58).

Analyses examining joint effect of age at menarche and BMI indicated a significant interaction with risk of vasomotor menopausal symptoms (P <.0001). Data from these analyses indicated the association of early menarche with often experiencing hot flashes was strong among those who were overweight (RRR, 2.36; 95% CI, 2.17-2.57) or obese (RRR, 2.87; 95% CI, 2.79-2.95) compared to those who were of normal weight (RRR, 1.10; 95% CI, 0.95-1.28).

For night sweats, women experiencing early menarche who were overweight (RRR, 2.04; 95% CI, 1.80-2.30) or obese (RRR, 2.42; 95% CI, 2.36-2.47) were also at a greater risk compared to those of normal weight (RRR, 1.24; 95% CI, 1.20-1.28).

This study, “Age at menarche and risk of vasomotor menopausal symptoms: a pooled analysis of six studies,” was published in BJOG: an International Journal of Obstetrics & Gynaecology.