Perinatology (Maternal–fetal medicine) is a branch of medicine that focuses on managing health concerns of the mother and fetus prior to, during, and shortly after pregnancy.

Maternal–fetal medicine specialists are physicians who subspecialize within the field of obstetrics. They may perform prenatal tests, provide treatments, and perform surgeries. They act both as a consultant during low-risk pregnancies and as the primary obstetrician in especially high-risk pregnancies. For the mother, perinatologists assist with pre-existing health concerns, as well as complications caused by pregnancy

Source: Wikipedia