Premature Labor

Overview

The uterus is a strong muscular organ, and like any muscle, it must work to stay in shape. When a muscle works, it is said to contract. When a muscle is not working, or is at rest, it is relaxed. It makes sense then that the uterus would need to contract to stay in shape and be able to stretch with a growing baby. As with all types of exercise, too much of a good thing can be not-so-good. Too much contracting of the uterus can lead to the cervix shortening (effacement) or opening (dilation). When your uterus contracts and starts to shorten or open your cervix before you are full term, it is called premature, or preterm, labor. Preterm labor occurs prior to thirty-seven weeks of your pregnancy. Preterm labor is most serious when it leads to preterm delivery.

The only way your care provider can determine whether your cervix has changed is to do a vaginal exam and feel your cervix or to use a special ultrasound device that gently slips into the vagina and produces an ultrasound picture of your cervix onto a screen. This picture is "frozen" on the screen and your cervix can then be measured. This type of ultrasound measurement is highly technical, but it gives a very accurate measurement of your cervix.

In most cases, the cause of preterm labor is unknown, but there are many things that contribute to a cervix shortening and opening.

Who Gets Preterm Labor?

Many women in general will fall into the category of "at risk" for preterm labor, and some women will be at "high risk" for preterm labor. This range will depend on the number of risk factors as well as the severity of the factors that put them at risk. As you review this list of things that lead to preterm labor, check off those that apply to you.

Factors that make a mother at risk for preterm labor:

• previous preterm labor or birth
• infections such as urinary tract or vaginal
• multiple babies: twins, triplets, or quads
• an abnormally shaped uterus or defects in the uterus such as fibroids
• previous surgery on the uterus
• previous surgery on the cervix such as cone, LEEP, or laser
• cervical incompetence (the cervix shortens and opens without contractions)
• exposure to Diethylstilbestrol (DES)
• if the mother is younger than eighteen or older than thirty-five years of age
• if the mother weighs less than 100 pounds
• too much or too little amniotic fluid
• abnormalities of the baby such as birth defects
• problems with the placenta working properly (caused by high blood pressure, high MSAFP, chronic diseases, etc.)
• bleeding during pregnancy
• placenta previa
• late or no prenatal care
• chronic illness
• premature rupture of membranes (your "water breaks")
• abdominal surgery during pregnancy
• smoking and drug use