Physiologic changes of pregnancy include insulin resistance, thrombophilia, immunosuppression, and hypervolemia. These changes may herald the development of disease in later life.To summarize current evidence on how pregnancy reveals risk of chronic disease.MEDLINE was searched for articles published between 1990 and 2005 relating pregnancy conditions to the development of chronic disease. Bibliographies and the Web sites of the International Society of Obstetric Medicine and International Society for the Study of Hypertension in Pregnancy were also reviewed.Pregnancy exaggerates atherogeniclike responses, including insulin resistance and dyslipidemia, manifesting as preeclampsia or gestational diabetes. These complications herald an increased risk of postpartum cardiovascular disease, with a 2-fold increased risk of coronary artery disease and stroke. Women with gestational diabetes mellitus can progress to type 2 diabetes mellitus. The rate of progression varies from 6% to 92% depending on diagnostic criteria, race/ethnicity, and duration of surveillance (from 6 months to 28 years). Pregnancy increases risk of venous thrombosis by 7- to 10-fold. Heritable thrombophilia is present in at least 15% of Western populations and underlies at least 50% of gestational venous thromboses. Thus, the procoagulant changes during pregnancy can unmask hereditary thrombophilia. An important adaptation leading to immunotolerance of the fetoplacental unit is a switch from helper T-cell (T(H)) 1 dominance to T(H)2 dominance. Patients with a T(H)1-dominant immune disease, such as rheumatoid arthritis or multiple sclerosis, improve during pregnancy. However, rheumatoid arthritis is 5 times more likely to develop after delivery than at any other time. During pregnancy, there is a 50% increase in plasma volume, which can unmask glomerulopathies, peripartum cardiomyopathy, arterial aneurysms, or arteriovenous malformations. Development of intrahepatic cholestasis of pregnancy predicts increased risk of later cholelithiasis.The physiologic changes of pregnancy can reveal risk of chronic diseases. Exaggerated responses reflective of the metabolic syndrome are seen in preeclampsia and gestational diabetes and can herald future cardiovascular and metabolic disease. Pregnancy is therefore an important screening opportunity for cardiovascular and metabolic disease risk factors, with the possibility of early intervention.