Laine K, et al. - Through a population-based cohort study of 929,963 deliveries with 16,174 twin pregnancies in 1999–2014 taken from Medical Birth Registry of Norway and Statistics Norway, the experts intended to evaluate the prevalence and risk of pre-eclampsia and gestational hypertension (most common complication that happens during pregnancy and one of the most common reasons for maternal and fetal mortality and morbidity globally) in twin pregnancies in comparison with singleton pregnancies. In the study population, the prevalence of pre-eclampsia was 3.7%. The OR for pre-eclampsia in twin pregnancies was three to fourfold as that of singleton pregnancies. Twin pregnancy persisted as an independent risk factor for pre-eclampsia, even after adjusting for known risk factors. The prevalence of gestational hypertension in women with singleton pregnancies and in those with twin pregnancies was 1.7% and 2.2%, respectively. Gestational hypertension had no marked association with a twin pregnancy, after adjustment for known risk factors. Hence, despite the maternal age, parity, educational level, smoking, maternal comorbidity or in vitro fertilization, the risk of pre-eclampsia in twin pregnancies was three to fourfold in comparison with singleton pregnancies. Moreover, in women with twin pregnancies, the risk of gestational hypertension was not elevated post-adjustment for the main risk factors.