Fetoscopy - An uncommon type of prenatal testing performed in the second trimester when birth defects, such as spina bifida are suspected. During fetoscopy, a small telescope is passed through the abdomen into the uterus to examine the fetus.

Fetus - The stage of human development from 10 weeks' gestation until birth.

Folic acid (folate) - A B vitamin necessary for the development of red blood cells in the mother. Folic acid deficiency has been associated with neural tube defects in the fetus. The vitamin is found in oranges, leafy green vegetables, and lentils, among other foods.

Fontanel - One of two soft spots on a newborn's head at which the bones of the baby's still-forming skull do not yet meet. They usually close by 18 months.

Forceps extraction - The assisted delivery of a baby using forceps, a metal instrument resembling hinged salad tongs, with ends curved to fit a baby's head. Forceps are inserted into the vagina and placed around the baby's head to guide him through the birth canal.

Fallopian tube - One of two ducts, that carries the egg to the uterus. The egg travels towards the uterus, pushed along by movements of the cilia on the inner lining of the tubes.

Failure to Progress - A term used to describe the lack of progressive cervical dilation or lack of descent of the fetal head, or both.

Fertilization - The penetration of the egg by sperm.

Fetal alcohol syndrome (FAS) - Physical, mental, and behavioral problems in a baby resulting from alcohol abuse by the mother during pregnancy. Babies with FAS may have small bodies, abnormal facial features, heart defects, and problems with joints and limbs.

Fetal fibronectin (fFN) - A protein that, when present in the vagina, can indicate that the placenta and amniotic sac are starting to separate and labor is imminent.

Fetal growth retardation - (also called intrauterine growth retardation, or IUGR) Inadequate fetal growth, which can be caused by a variety of conditions and circumstances, including hypertension, smoking, poor weight gain, fetal viral infections, kidney disease, and improper nutrition of the mother.

Fetal monitor - A device used before or during labor to listen to the fetal heart rate. Fetal monitoring can be done by placing the monitor on the expectant mother's abdomen (externally) or through the vagina (internally).

Fetal distress - A situation, usually detected by an abnormal heartbeat or an irregular rhythm observed during fetal monitoring. These problems can occur before birth or during labor.