This issue Obstetrics and Gynecology Clinics examines Medical Complications in Pregnancy. Guest Editor Dr. Judith Hibbard has assembled a panel of experts who offer reviews on topics including Preeclampsia, Chronic hypertension, Peripartum cardiomyopathy, Valvular heart disease in pregnancy, Pregestational diabetes, Asthma management, Management of renal disease, Renal transplant recipients and pregnancy, Sickle disease and pregnancy, Thyroid disease, Update on gestational diabetes, Pregnancy after gastric bypass, Thromboprophylaxis in obstetrics, Cholestasis of pregnancy, and Hepatitis: screening and management.