Long-term blood pressure changes measured from before to after pregnancy relative to nonparous women.
OBJECTIVE
To prospectively examine whether blood pressure changes persist after pregnancy among women of reproductive age.


METHODS
This was a prospective, population-based, observational cohort of 2,304 (1,167 black, 1,137 white) women (aged 18-30 years) who were free of hypertension at baseline (1985-1986) and reexamined up to six times at 2, 5, 7, 10, or 20 years later (2005-2006). We obtained standardized blood pressure measurements before and after pregnancies and categorized women into time-dependent groups by the cumulative number of births since baseline within each time interval (zero births [referent]; one interim birth and two or more interim births; nonhypertensive pregnancies). The study assessed differences in systolic and diastolic blood pressures among interim birth groups using multivariable, repeated measures linear regression models stratified by baseline parity (nulliparous and parous), adjusted for time, age, race, baseline covariates (blood pressure, body mass index, education, and oral contraceptive use), and follow-up covariates (smoking, antihypertensive medications, oral contraceptive use, and weight gain).


RESULTS
Among nulliparas at baseline, mean (95% confidence interval) fully adjusted systolic and diastolic blood pressures (mm Hg), respectively, were lower by -2.06 (-2.72 to -1.41) and -1.50 (-2.08 to -0.92) after one interim birth, and lower by -1.89 (-2.63 to -1.15) and -1.29 (-1.96 to -0.63) after two or more interim births compared with no births (all P<.001). Among women already parous at baseline, adjusted mean blood pressure changes did not differ by number of subsequent births.


CONCLUSIONS
A first birth is accompanied by persistent lowering of blood pressure from preconception to years after delivery. Although the biologic mechanism is unclear, pregnancy may create enduring alterations in vascular endothelial function.


METHODS
II.
Gunderson
Erica P
EP
From the Division of Research, Epidemiology and Prevention, Kaiser Permanente, Oakland, California; Division of Preventive Medicine, University of Alabama at Birmingham, Birmingham, Alabama; Department of Epidemiology, Graduate School of Public Health, University of Pittsburgh, Pittsburgh, Pennsylvania; Department of Obstetrics and Gynecology, Magee-Womens Hospital, University of Pittsburgh, Pittsburgh, Pennsylvania; and Division of Prevention and Population Sciences, National Heart, Lung, and Blood Institute, Bethesda, Maryland.
Chiang
Vicky
V
Lewis
Cora E
CE
Catov
Janet
J
Quesenberry
Charles P
CP
Sidney
Stephen
S
Wei
Gina S
GS
Ness
Roberta
R
D000293:Adolescent; D000328:Adult; D001741:Black or African American; D000375:Aging / Q000502:physiology; D001794:Blood Pressure / Q000502:physiology*; D004730:Endothelium, Vascular / Q000502:physiology; D005260:Female; D006801:Humans; D008137:Longitudinal Studies; D008875:Middle Aged; D010298:Parity; D011247:Pregnancy / Q000502:physiology*; D044465:White People; D055815:Young Adult