Duration of lactation and risk factors for maternal cardiovascular disease.
OBJECTIVE
To examine dose-response relationships between the cumulative number of months women lactated and postmenopausal risk factors for cardiovascular disease.


METHODS
We examined data from 139,681 postmenopausal women (median age 63 years) who reported at least one live birth on enrolling in the Women's Health Initiative observational study or controlled trials. Multivariable models were used to control for sociodemographic (age, parity, race, education, income, age at menopause), lifestyle, and family history variables when examining the effect of duration of lactation on risk factors for cardiovascular disease, including obesity (body mass index [BMI] at or above 30), hypertension, self-reported diabetes, hyperlipidemia, and prevalent and incident cardiovascular disease.


RESULTS
Dose-response relationships were seen; in fully adjusted models, women who reported a lifetime history of more than 12 months of lactation were less likely to have hypertension (odds ratio [OR] 0.88, P<.001), diabetes (OR 0.80, P<.001), hyperlipidemia (OR 0.81, P<.001), or cardiovascular disease (OR 0.91, P=.008) than women who never breast-fed, but they were not less likely to be obese. In models adjusted for all above variables and BMI, similar relationships were seen. Using multivariate adjusted prevalence ratios from generalized linear models, we estimate that among parous women who did not breast-feed compared with those who breast-fed for more than 12 months, 42.1% versus 38.6% would have hypertension, 5.3% versus 4.3% would have diabetes, 14.8% versus 12.3% would have hyperlipidemia, and 9.9% versus 9.1% would have developed cardiovascular disease when postmenopausal. Over an average of 7.9 years of postmenopausal participation in the Women's Health Initiative, women with a single live birth who breast-fed for 7-12 months were significantly less likely to develop cardiovascular disease (hazard ratio 0.72, 95% confidence interval 0.53-0.97) than women who never breast-fed.


CONCLUSIONS
Among postmenopausal women, increased duration of lactation was associated with a lower prevalence of hypertension, diabetes, hyperlipidemia, and cardiovascular disease.
Schwarz
Eleanor Bimla
EB
From the Department of Medicine, University of Pittsburgh, Pittsburgh, Pennsylvania; the Division of Public Health Sciences, Fred Hutchinson Cancer Research Center, Seattle, Washington; the Division of Maternal-Fetal Medicine, University of North Carolina School of Medicine, Chapel Hill, North Carolina; the University of California, San Diego, La Jolla, California; and the Department of Epidemiology, Graduate School of Public Health, University of Pittsburgh, Pittsburgh, Pennsylvania.
Ray
Roberta M
RM
Stuebe
Alison M
AM
Allison
Matthew A
MA
Ness
Roberta B
RB
Freiberg
Matthew S
MS
Cauley
Jane A
JA
D000328:Adult; D000368:Aged; D001942:Breast Feeding / Q000453:epidemiology*; D002318:Cardiovascular Diseases / Q000453:epidemiology* / Q000517:prevention & control; D015331:Cohort Studies; D003920:Diabetes Mellitus / Q000453:epidemiology; D005260:Female; D006801:Humans; D007774:Lactation / Q000502:physiology*; D008019:Life Style; D008875:Middle Aged; D009765:Obesity / Q000453:epidemiology; D017698:Postmenopause; D015995:Prevalence; D012307:Risk Factors; D012959:Socioeconomic Factors; D055815:Young Adult