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Basic Pregnancy Terminology

Understanding Pregnancy Basics in Miscarriage and Pregnancy Loss


Updated December 08, 2011

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

While you may be familiar with a lot of the words and phrases used by doctors, nurses, and in online resources like this, occasionally you'll encounter a word you just don't know. In the case of pregnancy loss, it can be hard to understand how those terms and phrases fit into your personal experience. Below, you'll find a list of some terms the come up frequently in discussions of pregnancy, miscarriage, and pregnancy loss. Follow the highlighted links for in-depth information when it's available.


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 referred to as stillbirth), the baby may have to be delivered by c-section.


A.D.A.M. Health Encyclopedia
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. During labor, it begins to dilate, eventually opening large enough to allow the baby to pass out of the uterus into the vagina on the way to being born. The cervix can open prior to labor, especially in women who have been pregnant before. Usually, there is no affect on the pregnancy, but an opening cervix in early pregnancy can result in miscarriage.

Fallopian Tube

Part of the female reproductive system, the fallopian tubes lead from the ovaries to the uterus. When an egg is released from the ovary during ovulation, it enters the fallopian tubes. For fertilization to lead to pregnancy, it needs to occur in the fallopian tube. If a fertilized egg implants in the fallopian tube, it is called a tubal pregnancy and can be a life threatening emergency. If the fallopian tubes become damaged due to infection, infertility can result.


The moment when a male reproductive cell (sperm) penetrates the outer layer of the female reproductive cell (ovum) causing the genetic material of the mother and father to mix into a new cell, which is called a zygote.

Fertilized Egg

Another name for a zygote, or new cell created at the moment a sperm and egg are joined.


The medical term for an unborn baby who is more than 10 weeks gestation. Prior to that point, a developing human is called an embryo.

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 age 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 prematurely.


The time when a developing embryo adheres to the uterine lining after an egg (ovum) is fertilized in the fallopian tube. Occasionally, implantation is associated with some vaginal bleeding, which can be disturbing to women in early pregnancy.

Last Menstrual Period

A woman’s last period prior to becoming pregnant. The first day of the last menstrual period (LMP) is used to calculate the due date.

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