Lactation and changes in maternal metabolic risk factors.
OBJECTIVE
To examine the relationship between duration of lactation and changes in maternal metabolic risk factors.


METHODS
This 3-year prospective study examined changes in metabolic risk factors among lactating women from preconception to postweaning and among nonlactating women from preconception to postdelivery, in comparison with nongravid women. Of 1,051 (490 black, 561 white) women who attended two consecutive study visits in years 7 (1992-1993) and 10 (1995-1996), 942 were nongravid and 109 had one interim birth. Of parous women, 48 (45%) did not lactate, and 61 (55%) lactated and weaned before year 10. The lactated and weaned women were subdivided by duration of lactation into less than 3 months and 3 months or more. Multiple linear regression models estimated mean 3-year changes in metabolic risk factors adjusted for age, race, parity, education, and behavioral covariates.


RESULTS
Both parous women who did not lactate and parous women who lactated and weaned gained more weight (+5.6, +4.4 kg) and waist girth (+5.3, +4.9 cm) than nongravid women over the 3-year interval; P<.001. Low-density lipoprotein cholesterol (+6.7 mg/dL, P<.05) and fasting insulin (+2.6 microunits, P=.06) increased more for parous women who did not lactate than for nongravid and parous women who lactated and weaned. High-density lipoprotein cholesterol decrements for both parous women who did not lactate and parous women who lactated and weaned were 4.0 mg/dL greater than for nongravid women (P<.001). Among parous, lactated and weaned women, lactation for 3 months or longer was associated with a smaller decrement in high-density lipoprotein cholesterol (-1.3 mg/dL versus -7.3 mg/dL for less than 3 months; P<.01).


CONCLUSIONS
Lactation may attenuate unfavorable metabolic risk factor changes that occur with pregnancy, with effects apparent after weaning. As a modifiable behavior, lactation may affect women's future risk of cardiovascular and metabolic diseases.


METHODS
II.
Gunderson
Erica P
EP
Division of Research, Epidemiology and Prevention Section, Kaiser Permanente, Oakland, California 94612, USA. epg@dor.kaiser.org
Lewis
Cora E
CE
Wei
Gina S
GS
Whitmer
Rachel A
RA
Quesenberry
Charles P
CP
Sidney
Steve
S
D000328:Adult; D001786:Blood Glucose / Q000032:analysis; D002318:Cardiovascular Diseases / Q000453:epidemiology; D002784:Cholesterol / Q000097:blood; D008078:Cholesterol, LDL / Q000097:blood; D003327:Coronary Disease / Q000453:epidemiology*; D004734:Energy Metabolism; D005260:Female; D006706:Homeostasis / Q000502:physiology; D006801:Humans; D007774:Lactation / Q000502:physiology*; D015337:Multicenter Studies as Topic; D011247:Pregnancy; D011446:Prospective Studies; D012307:Risk Factors; D013997:Time Factors; D014886:Weaning
D001786:Blood Glucose; D008078:Cholesterol, LDL; D002784:Cholesterol