Maternal-fetal medicine (MFM) is the branch of obstetrics that focuses on the medical and surgical management of high-risk pregnancies. Management includes monitoring and treatment including comprehensive ultrasound, chorionic villus sampling, genetic amniocentesis, and fetal surgery or treatment. Obstetricians who practice maternal-fetal medicine are also known as perinatologists. This is a subspecialty to obstetrics and gynecology mainly used for patients with high-risk pregnancies. Obstetric medicine is a closely related specialty that emphasizes the care of medical problems in pregnancy.