Instead, the study examined blood pressure as a continuous measure, using genetic data to assess how increases in blood pressure across its full range may influence pregnancy outcomes. This approach to the study allowed researchers to better determine whether higher blood pressure itself plays a causal role in these complications. However, high blood pressure during pregnancy may be more common than many people realize. “High blood pressure is a common medical problem encountered in pregnancy, with approximately one in ten pregnant women affected.”According to the Mayo Clinic, there are four main types of high blood pressure that can occur during pregnancy. The first is chronic hypertension, which occurs when high blood pressure develops either before pregnancy or during the first 20 weeks of pregnancy.