Does long-term lactation protect premenopausal women against hypertension risk? A Korean women's cohort study

Prev Med. 2005 Aug;41(2):433-8. doi: 10.1016/j.ypmed.2004.11.025.


Background: Little is known about the long-term effect of lactation on maternal cardiovascular health except for a few animal or human experimental studies. The objective of this study was to examine the effects of lactation on the incidence of hypertension in premenopausal women.

Methods: The data were derived from a cohort study with 6 years follow-up (1995-2000). The cohort was composed of 177,749 Korean premenopausal women, aged 20-59, who had medical evaluations in 1992 and 1994. During the follow-up, blood pressure was measured as part of the 1996, 1998, and 2000 periodic examinations.

Results: In multivariate Cox proportional hazard models, lactation decreased the risk of hypertension (risk ratio, 0.92; 95% confidence interval, 0.90-0.96). Compared with women who with no history of lactation, 1-6 months of lactation decreased the risk of hypertension (RR, 0.90; 95% CI, 0.87-0.93), as did 7-12 months (RR, 0.92; 95% CI, 0.87-0.98) or 13-18 months (RR, 0.93; 95% CI, 0.86-0.99). In particular, the coexistence of obesity and no lactation increased the risk of hypertension (P for interaction = 0.028).

Conclusion: This finding suggests that lactation may be a protective factor against hypertension among premenopausal women.

MeSH terms

  • Adult
  • Female
  • Humans
  • Hypertension / epidemiology*
  • Hypertension / prevention & control
  • Incidence
  • Korea / epidemiology
  • Lactation / physiology*
  • Middle Aged
  • Multivariate Analysis
  • Obesity / physiopathology
  • Premenopause*
  • Proportional Hazards Models
  • Prospective Studies
  • Risk