The
positive associations between these variables and the risk of gestational hypertension were weaker and
nonsignificant. Compared with underweight women (body mass index < 19.8), obese women (body mass
index > 29) had increased risks of both gestational hypertension (odds ratio = 4.85, 95% confidence interval
1.97-11.92) and preeclampsia (odds ratio = 5.19, 95% confidence interval 2.35-11.48). Significantly lower
risks of preeclampsia and gestational hypertension were observed for women born outside Nordic countries
and in association with maternal smoking and summer birth.