Pregnancy typically lasts about 40 weeks. Babies born before 37 weeks are preterm and usually are not fully grown. This occurs in about 12% of babies born in the United States each year. The earlier the baby is born, the greater the risk of a problem. Preterm birth accounts for 75% of newborn deaths that are not related to birth defects. Preterm babies may have problems right away that need special care in the hospital, and they may have long-term problems, including learning and behavioral problems and trouble with vision, hearing, and breathing.
Preterm labor can happen to anyone, without warning. Some of the following factors have been linked to preterm labor:
* Past pregnancies with preterm labor or birth
* Special problems in current pregnancy
* Multiple pregnancy
* Abdominal surgery during pregnancy
* Infection in the mother
* Bleeding in mid-pregnancy
* Weight of the mother less than 110 pounds
* Previous pregnancy loss in second trimester
* Premature rupture of membranes (“water breaks” too
soon)
* High blood pressure
* Chronic illness in the woman
* Too much fluid in the amniotic sac
* Birth defects in the baby
Defects in the uterus, such as an incompetent cervix, also have been linked to preterm labor. A cervix is called incompetent when it opens before the full term of pregnancy. The causes of this are not certain. An ultrasound exam may be done to measure the length of the cervix.
For some women with an incompetent cervix, a procedure called cerclage may be done. Cerclage is a procedure that “stitches” the cervix closed. The stitch usually is taken out at the 37th week of pregnancy.
Signs of Preterm Labor:
¨ Change in vaginal discharge (becomes watery, mucus- like,
or bloody)
¨ Increase in amount of vaginal discharge
¨ Pelvic or lower-abdominal pressure
¨ Constant, low, dull backache
¨ Mild abdominal cramps, with or without diarrhea
¨ Regular or frequent contractions or uterine tightening,
often painless (four times every 20 minutes or 8 times an
hour for more than one hour)
¨ Ruptured membranes (your water breaks—whether a gush
or a trickle)
The earlier a baby is born, the less developed he or she is. This can lead to breathing problems (such as respiratory distress syndrome), feeding problems, or an increased risk of infection. Survival rates are best for babies after 24 weeks. After 32 weeks the baby is less likely to have long-term problems.
The American College of Obstetricians and Gynecologists. Your Pregnancy & Birth: Information You Can Trust from the Leading Experts in Women’s Health Care. 4th ed. 2005