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Basic Labor Terminology

Understanding Labor and Delivery Basics in Miscarriage and Pregnancy Loss


Updated February 19, 2012

Written or reviewed by a board-certified physician. See About.com's Medical Review Board.

Pregnancy loss can happen at any stage of pregnancy. If it's your first pregnancy, you might not have taken birth classes, or even have had a chance to read pregnancy books when your miscarriage begins. If you're looking for basic labor and delivery terms you might hear during your treatment, you'll find a list. These definitions are tailored to pregnancy loss with links to more general information when it's available.

Bag of Waters

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In pregnancy, a fetus is suspended in amniotic fluid, which is contained in a thick balloon-like membrane. The membrane extends out from the placenta and protects the baby throughout pregnancy. At some point in labor, the bag of waters will either break spontaneously or be broken by your doctor or midwife. When the bag of waters breaks too early in pregnancy, it is called preterm premature rupture of membranes (PPROM), which can lead to miscarriage, infection, preterm labor, or a premature birth.


When a baby is positioned with the head at the top of the uterus, it is considered a breech position. There are several types of breech positions, based on the position of the feet relative to the rest of the body. In early pregnancy loss, a breech baby can be delivered vaginally. If a baby is positioned breech later in a pregnancy that results in intrauterine fetal demise (commonly known as stillbirth), the baby may have to be delivered by c-section.


Part of the female reproductive system, the cervix is the tunnel-like opening to the uterus. It is a strong, ring-shaped muscle that is normally closed. The cervix can open prior to labor, especially if you’ve already had a baby, but an open cervix can also result in pregnancy loss. During labor, the cervix begins to dilate, eventually opening large enough (10cm in a full-term pregnancy) to allow the baby to pass out of the uterus into the vagina on the way to being born.


When the muscles of the uterus “tighten” or “cramp” in a rhythmic pattern during pregnancy, the tightenings are called contractions. In labor, or preterm labor, contractions cause the cervix to dilate, or open, eventually leading to the birth of the fetus. Contractions can also happen outside of labor, but generally don’t organize into a regular pattern in those circumstances. Contractions can be an early sign of miscarriage or preterm labor and should be monitored.


A pain control method for labor. An anesthesiologist places a thin, flexible catheter in the fluid surrounding the spine. Special numbing medications are given continuously by a computerized pump. Pain is controlled by numbing you from the top of the abdomen down. Epidurals can be used in pregnancy loss as well, depending on the size of the fetus and the delivery method needed by your personal circumstances.


A small cut made at the bottom of the vagina by your doctor or midwife at the time of delivery to ease the passage of the baby’s head through the vagina. Episiotomies are not often necessary for pregnancy losses, and usually only in a full-term, or near-term delivery. The cut must be repaired with stitches after delivery.


The medical term for an unborn baby who is greater than 10 weeks gestation. Prior to that point, a developing human is called a zygote (at the time of conception), and then an embryo. An baby is called a fetus up until the moment of birth, at which time he or she is called an infant.

First Stage of Labor

The time between when the cervix starts to dilate and the time it is fully dilated. In a full-term delivery, this stage ends when the cervix is 10cm dilated. In preterm labor, or miscarriage, the cervix may not dilate to a full 10cm before the fetus can be delivered.

Full Term

A pregnancy is considered “full term” if it is between 37 and 42 weeks gestation. A pregnant woman is given a “due date” estimated to be 40 weeks after the first day of her last menstrual period. However, this is only an estimated date based on the average length of pregnancy. Babies born up to three weeks before that estimate date are likely to be born without any of the complications associated with preterm delivery. Babies born after their due date are also at little risk for complications until after week 42. At that point, the risk of stillbirth increases dramatically.

Gestational Age

A way of measuring a baby’s age during a pregnancy. Gestational ge is calculated from the first day of a woman’s last menstrual period, which actually includes approximately two weeks prior to conception. Gestational age is universally used by medical practitioners to measure a baby’s progress from size to expected complications if a baby is born preterm. The gestational age may also determine if your pregnancy loss is called a miscarriage or stillbirth.

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