Afterpains - Uterine contractions that may cause discomfort after delivery, especially during nursing. Oxytocin causes the uterus to contract, which may lead to cramping.

Anesthesia - Drugs that block local or regional pain or render a patient unconscious (called general anesthesia), preventing awareness of pain.

Angioma - A tumor, usually benign, or the swelling of lymph and blood vessels.

Areola - The darker skin around the nipple.

Artificial Rupture of Membranes (ARM) - This method for inducing labor works when the doctor ruptures the amniotic membrance artifically. He uses a sterile, plastic, thinhook to break the amniotic membranes. This procedure releases a gush of warm amniotic fluid from the vagina.

Auscultation - A way of listening to the baby's heartbeat during labor, using either a special stethoscope or a Doppler ultrasound device.

Apgar score - A score given to a newborn after being tested on several measures immediately after birth. The baby's heart rate, color, respiratory effort, muscle tone, and reflexes are measured at 1 minute and again at 5 minutes following delivery. A perfect Apgar score is 10, with the average being 7 to 9.

Amniocentesis - A procedure in which a needle is inserted through the abdomen into the uterus. A small amount of amniotic fluid is taken from the sac surrounding the fetus and tested for chromosomal or genetic abnormalities or other diseases.

Abruptio placentae - When the placenta begins to separate from the wall of the uterus before the baby is born, usually in the second and third trimester. Symptoms include sudden abdominal pain, hardness in the abdomen, vaginal bleeding, and lower back pain.

Active labor - The part of the first stage of labor during which the cervix dilates from 4 centimeters to 10 centimeters, contractions become stronger, and pressure and discomfort build.

Afterbirth - See placenta.

Alpha fetoprotein (AFP) - A protein in the blood of the growing fetus. It is also present in amniotic fluid and in the mother's blood. Elevated levels may indicate that the baby has a neural tube defect such as spina bifida.

Amniotic fluid - The fluid inside the sac which holds the fetus.

Amniotic sac - The fluid-filled sac in the mother's uterus where the fetus grows.

Analgesic - Medication given intravenously or intramuscularly to provide pain relief and relaxation. Analgesics do not result in a total loss of feeling, as anesthetic drugs do, though analgesics may slow down labor, especially if given too early in labor.

Anemia - A condition in which the blood is low in red blood cells, hemoglobin, or in total volume. Anemia is common in pregnancy, but easily treatable.

Anencephaly - A fatal neural tube defect in which the fetus's head and brain fail to develop normally and the neural tube remains open at the top.