Impact of pregnancy-induced hypertension on birthweight by gestational age

Few studies to date have examined the effect of severe pre-eclampsia, pre-eclampsia, and gestational hypertension on birthweight according to gestational age. We conducted a population-based retrospective cohort study of 16 936 pregnant women in Suzhou, China. Analysis of variance and multivariable linear regression were performed to compare the mean birthweights of babies born to mothers with gestational hypertension, pre-eclampsia, and severe pre-eclampsia with birthweights of infants born to mothers with normal blood pressure at each week of gestation. The differences in mean birthweight between women with severe pre-eclampsia and women with normal blood pressure ranged between -467.7 g and 189.1 g. The birthweights were statistically significantly lower in women with severe pre-eclampsia than in women with normal blood pressure for gestational age categories less than or equal to 35 and 36 weeks. However, after adjustment for confounding variables, the birthweights were not statistically significantly different in women with severe pre-eclampsia when compared with women with normal blood pressure even at less than or equal to 35 and 36 weeks. The differences in mean birthweight between women with pre-eclampsia and women with normal blood pressure ranged between -132.2 g and 174.6 g. These differences were not statistically significant, before or after adjusting for confounding variables. There were no differences in mean birthweight between women with gestational hypertension and women with normal blood pressure. Further analysis suggested that pre-eclampsia and gestational hypertension were associated with increased rates of both small-for-gestational-age and large-for-gestational-age infants. The majority of the babies born to mothers with different types of pregnancy-induced hypertension were appropriate-for-gestational-age or even large-for-gestational- age. In this Chinese population, most babies born to mothers with severe pre-eclampsia or pre-eclampsia and gestational hypertension had similar fetal growth to those born to normotensive mothers.