Alveoli - tiny sacs that are the smallest airways of the lungs.

Cervical cerclage - a procedure used to suture the cervical opening. Cervical cerclage is performed on a woman with an incompetent cervix.

Corticosteroid - medication given to the pregnant woman to help mature the lungs of the fetus.

Fetal fibronectin (FFN) - a protein that helps "glue together" the lining of the uterus and the amniotic sac.

Fetus - an unborn baby from the eighth week after fertilization until delivery.

Fundus - the top of the enlarged uterus.

Kegel exercises - pelvic floor exercises that help tone the muscles in the vagina and perineum.

Lanugo - fine, downy hair that covers the fetus until shortly before or after birth.

Methylmercury - a form of mercury that can be dangerous to an unborn baby.

Pediatrics - the branch of medicine that deals with diagnosis, treatment, and prevention of diseases in children.

Preeclampsia - a condition characterized by pregnancy-induced high blood pressure, protein in the urine, and swelling (edema) due to fluid retention.

Premature - describes a baby born before 37 completed weeks of pregnancy.

Preterm labor - labor that begins before 37 completed weeks of pregnancy.

Round ligaments - ligaments that attach to both sides of the uterus and extend down into the groin.

Surfactant - a substance in the lungs that helps keep the tiny air sacs open.

Tocolytics - medications administered to help slow or stop contractions.

Ultrasound - a diagnostic imaging technique that uses high-frequency sound waves to create an image of the fetus' body and organs and the surrounding tissues.

Vernix caseosa (also called vernix) - a white substance that covers the skin of the fetus during pregnancy and helps to protect the fetus.