Smoking, hemoglobin concentration and pregnancy-induced hypertension

The aim of the study was to assess the effect of cigarette smoking on first- to second-trimester change in hemoglobin (Hb) concentration and the presence of pregnancy-induced hypertension (PIH). In smokers and non-smokers the mean difference between the first- and second-trimester Hb concentration was 1.5-1.6 and 1.3 g/dl, respectively (p < 0.0001). The incidence of PIH among smokers and non-smokers was 4.0 and 7.5%, respectively (p < 0.0001). The risk of PIH increased with increasing second-trimester Hb. After adjustment for factors including previous pregnancies, maternal age and weight gain by logistic regression analysis, the increased Hb declined and the decreased incidence of PIH in smokers persisted.