A pregnancy is typically considered at-risk when an expectant mother also has additional acute or chronic health concerns, explains OB/GYN Kyoko Peña-Robles with One Medical Group in San Francisco. "There are a number of factors that could cause a pregnancy to be classified higher risk than normal," she says. These factors can include underlying chronic medical conditions like Type 1 or Type 2 diabetes, chronic hypertension, thyroid disease or drug or alcohol abuse, as well as a history of preterm labor, preeclampsia, or miscarriage. If you're expecting twins or multiples, your pregnancy also might be labeled high-risk, Peña-Robles says. Most pregnant women who are over 35 are also considered high-risk simply due to their age.