What Is Preterm Labor?
You may be experiencing early or preterm labor if uterine contractions become strong enough to cause dilatation, shortening, and thinning (effacement) of your cervix. Labor is preterm if it begins prior to 37 weeks gestation, (37 weeks from the first day of your last menstrual period or LMP).
Unfortunately, waiting for uterine contractions to result in cervical changes wastes valuable treatment time, so chances are your doctor will make a diagnosis of premature labor even when your cervical changes are minor or just beginning. This is a situation when the old adage, "better safe than sorry," really holds true.
Early treatment is more effective than later treatment (after labor has advanced). This is especially true because preterm delivery causes more death and illness for newborns than anything else except birth defects; and spontaneous preterm labor causes a large percentage of preterm deliveries.
The latest statistics on preterm births show that two percent of all deliveries will occur at less than 32 weeks (extreme prematurity); 5.5 percent between 32 and 35 weeks; and 4.2 percent at 36 to 37 weeks.
Who Is at Risk?
The risk of preterm delivery varies considerably. Some women have several times the risk of others. For example, women with a previous preterm delivery have two to three times the usual risk of having a preterm infant in a subsequent pregnancy (see following table). Some risk factors can be controlled (such as alcohol and illicit drug use), but other factors, such as age, multiple gestation, and uterine abnormalities, can't be controlled. All women should watch for the signs of preterm labor and avoid activities that can lead to preterm labor.
Lifestyle can influence your risk of preterm labor. These are some of the few risk factors for preterm labor that you can control:
- cigarette smoking
- alcohol use
- cocaine use
- short interval between subsequent pregnancies
- poor weight gain during pregnancy
Each of these factors can increase the risk of a low birth weight baby and, probably, preterm labor and delivery. The best time to begin preterm labor prevention is before conception, yet, many pregnancies are unplanned, making preconception counseling and preparation difficult.