Objective:Hypertensive disorders in pregnancy pose a major burden during pregnancy and are also associated with an increased risk for hypertension later in life. Plasma creatine kinase activity is identified in the general population as an independent risk factor for hypertension. We hypothesize that plasma creatine kinase activity is similarly associated with blood pressure during pregnancy.Methods:Women who participated in the 'Amsterdam Born Children and their Development-study' were eligible for the current study. The associations between plasma creatine kinase activity and blood pressure measurements during pregnancy, and between plasma creatine kinase activity and hypertensive disorders in pregnancy (gestational hypertension, HELLP, preeclampsia and eclampsia) were evaluated using multiple linear regression and logistic regression models.Results:In 3619 pregnant women, plasma creatine kinase activity was significantly associated with all blood pressure outcomes. This was most pronounced for the mean SBP throughout pregnancy, with a regression coefficient of 3.48 mmHg (CI 1.67-5.28, P < 0.001) per 1-unit logCK. With respect to the hypertensive disorders in pregnancy, we found a significant association between severe gestational hypertension diagnosed before 34 weeks of gestation (OR 9.16, CI 1.32-63.86, P = 0.025) per 1-unit logCK activity. HELLP and preeclampsia were not significantly associated.Conclusion:Our data show that plasma creatine kinase activity measured in early pregnancy is associated with blood pressure during pregnancy and associated with severe gestational hypertension diagnosed before 34 weeks of gestation, whereas no significant association was found between creatine kinase and other hypertensive disorders in pregnancy.