Maternal smoking and blood pressure in different trimesters of pregnancy: the Generation R study.
OBJECTIVE
Smoking during pregnancy is a risk factor for various adverse birth outcomes but lowers the risk of preeclampsia. Cardiovascular adaptations might underlie these associations. We examined the associations of smoking in different trimesters of pregnancy with repeatedly measured blood pressure and the risks of preeclampsia and pregnancy-induced hypertension in a low-risk population-based cohort of 7106 pregnant women.


METHODS
This study was embedded in a population-based prospective cohort study from early pregnancy onwards. Smoking and systolic and diastolic blood pressures were assessed by questionnaires and physical examinations in each trimester of pregnancy. Information about preeclampsia and pregnancy-induced hypertension was obtained from medical records.


RESULTS
Compared to nonsmoking women, both first-trimester-only and continued smoking were associated with a steeper increase for systolic blood pressure and a lowest mid-pregnancy level and steeper increase thereafter for diastolic blood pressure throughout pregnancy. We did not find any significant associations in risk of preeclampsia for first-trimester-only smoking (odds ratio of 1.28, 95% confidence interval 0.74, 2.21) and continued smoking (odds ratio of 0.83, 95% confidence interval 0.50, 1.36), respectively.


CONCLUSIONS
Our results suggest that both first-trimester-only and continued smoking are associated with persistent maternal cardiovascular adaptations during pregnancy. Strategies for prevention of smoking during pregnancy should be focused on the preconception period. The effects of early and late-pregnancy smoking on the risk of preeclampsia should be further explored. Our results should be carefully interpreted to the general population of pregnant women.
Bakker
Rachel
R
The Generation R Study Group, Erasmus Medical Center, Rotterdam, The Netherlands.
Steegers
Eric Ap
EA
Mackenbach
Johan P
JP
Hofman
Albert
A
Jaddoe
Vincent Wv
VW
D000293:Adolescent; D000328:Adult; D001794:Blood Pressure; D015331:Cohort Studies; D005260:Female; D006801:Humans; D008875:Middle Aged; D009426:Netherlands; D016017:Odds Ratio; D011225:Pre-Eclampsia / Q000175:diagnosis / Q000209:etiology; D011247:Pregnancy; D011249:Pregnancy Complications, Cardiovascular / Q000175:diagnosis* / Q000209:etiology; D011264:Pregnancy Trimesters; D012907:Smoking / Q000009:adverse effects*