A high-risk pregnancy is one in which there's a higher chance of complications. You can lower your risk by avoiding certain lifestyle factors, like smoking, drinking, using drugs, or being routinely exposed to dangerous chemicals. Various medical conditions can result in a high-risk pregnancy, such as high blood pressure, diabetes, R-h disease, and severe kidney or heart disease. A woman with these problems will likely experience a worsening of that condition during pregnancy. Women with a previous stillbirth, or who've had a premature or low birth weight infant should also be closely monitored. Other risk factors include being under age 15 or over 35, having twins, or being three weeks or more overdue. Infections during pregnancy pose still another hazard, including Rubella, herpes, hepatitis-B, toxoplasmosis (TOX-oh-plaz-MOE-sis), and AIDS. Although pregnancy is a normal, natural state, it puts stress on even a healthy body, due to changes in blood volume, hormone balance, and mechanical pressure. An expectant mother with a high-risk pregnancy may want to select an obstetrician (ob-steh-TRIH-shun) who's skilled in handling such complications. Finally, some women may not develop problems until labor. For more information on high-risk pregnancy, consult a health care provider.