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. 2023 Jan;130(1):89-98.
doi: 10.1111/1471-0528.17274. Epub 2022 Aug 22.

Impact of lifetime lactation on the risk and duration of frequent vasomotor symptoms: A longitudinal dose-response analysis

Natalie V Scime  1 , Alison K Shea  2   3 , Peter D Faris  1   4 , Erin A Brennand  1   5
Affiliations

Impact of lifetime lactation on the risk and duration of frequent vasomotor symptoms: A longitudinal dose-response analysis

Natalie V Scime et al. BJOG. 2023 Jan.

Abstract

Objective: To examine the association between lifetime lactation and risk and duration of frequent vasomotor symptoms (VMS).

Design: Prospective cohort.

Setting: USA, 1995-2008.

Sample: 2356 parous midlife women in the Study of Women's Health Across the Nation.

Methods: Lifetime lactation was defined as the duration of breastfeeding across all births in months. We used generalised estimating equations to analyse risk of frequent VMS and Cox regression to analyse duration of frequent VMS in years.

Main outcome measures: Frequent VMS (hot flashes and night sweats) were measured annually for 10 years, defined as occurring ≥6 days in the past 2 weeks.

Results: Overall, 57.1% of women reported hot flashes and 43.0% reported night sweats during follow-up. Lifetime lactation was inversely associated with hot flashes plateauing at 12 months of breastfeeding (6 months: adjusted odds ratio [AOR] 0.85, 95% confidence interval (CI) 0.75-0.96; 12 months: AOR 0.78, 95% CI 0.65-0.93) and was inversely associated with night sweats in a downward linear fashion (6 months: AOR 0.93, 95% CI 0.81-1.08; 18 months: AOR 0.82, 95% CI 0.67-1.02; 30 months: AOR 0.73, 95% CI 0.56-0.97). Lifetime lactation was associated with shorter duration of hot flashes and night sweats in a quadratic (bell-shaped) fashion. The association was strongest at 12-18 months of breastfeeding and significant for hot flashes (6 months: adjusted hazard ratio [AHR] 1.35, 95% CI 1.11-1.65; 18 months: AHR 1.54, 95% CI 1.16-2.03; 30 months: AHR 1.18, 95% CI 0.83-1.68).

Conclusions: Longer lifetime lactation is associated with decreased risk and duration of frequent VMS.

Keywords: breastfeeding; hot flashes; menopause; middle-aged; prospective studies; sweating; women's health.

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Conflict of interest statement

DISCLOSURES OF INTEREST

AKS has received honoraria from Pfizer and Bio-Syent, and has received grant funding from Pfizer. PDF is a shareholder and consultant and receives payment in convertible notes from ViTAA medical devices. EAB has received speaking fees from Searchlight Pharmaceuticals. NVS has no disclosures to report.

Figures

Figure 1.
Figure 1.
Association of lifetime lactation and frequent hot flashes [Caption: OR, odds ratio. CI, confidence interval. Adjusted models controlled for education, race/ethnicity, parity, smoking, and body mass index at baseline as time-fixed covariates, and age as a time-varying covariate.]
Figure 2.
Figure 2.
Association of lifetime lactation and frequent night sweats [Caption: OR, odds ratio. CI, confidence interval. Adjusted models controlled for education, race/ethnicity, parity, smoking, and body mass index at baseline as time-fixed covariates, and age as a time-varying covariate.]
Figure 3.
Figure 3.
Association of lifetime lactation and duration of frequent hot flashes [Caption: HR, odds ratio. CI, confidence interval. Adjusted models controlled for education, race/ethnicity, parity, smoking, and body mass index at baseline and age at first report of hot flashes. An HR>1 indicated shorter duration of frequent hot flashes compared to the reference group, which was lifetime lactation of 0 months.]
Figure 4.
Figure 4.
Association of lifetime lactation and duration of frequent night sweats [Caption: HR, odds ratio. CI, confidence interval. Adjusted models controlled for education, race/ethnicity, parity, smoking, and body mass index at baseline and age at first report of night sweats. An HR>1 indicated shorter duration of frequent night sweats compared to the reference group, which was lifetime lactation of 0 months.]
See this image and copyright information in PMC

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