Preterm Labor and Birth
Contractions and dilation (opening) of the cervix before 37 weeks of pregnancy are considered preterm, or premature, labor. A normal pregnancy lasts about 40 weeks after the first day of the last period (38 weeks after fertilization). The danger of preterm labor is that it will lead to the birth of a baby that has not fully developed, and therefore has a high risk of complications. About 10% of all pregnancies result in premature birth. About 60% of serious complications or infant deaths are due to consequences of premature birth.
Preterm labor can be extremely frightening, because mothers-to-be quite naturally fear that their baby will be born too early and suffer the problems of prematurity. If your baby is born too soon, there is a great chance that her lungs will be underdeveloped. If so, she'll need to be put onto a ventilator that can breathe for her. Receiving oxygen through a ventilator can lead to complications.
Your baby may also have trouble maintaining a normal body temperature, and may become hypothermic (too cold). She'll need to be kept warm. Your baby might be so early that she can't coordinate her muscles to suck and swallow. If this is the case, she'll have to be fed through a needle in the vein (intravenously), or through a tube passed into her nose, down her throat and into her stomach. A premature baby may also develop complications such as bleeding into the brain; an increased risk of infections, especially meningitis and sepsis; problems with kidney function; and jaundice. Premature babies are at higher risk for long-term complications, which may include vision impairment or blindness, hearing impairment, cerebral palsy and chronic lung problems. The earlier the baby is born, the more likely that she will have these complications.
You are more likely to experience preterm labor if:
- You have had preterm labor or delivered a premature infant in the past.
- You are carrying more than one baby (such as twins or triplets).
- Your mother used the medication diethylstilbestrol (DES) while she was pregnant with you.
- You have an abnormally shaped uterus or an abnormal cervix.
- You have had a cone biopsy of your cervix in the past.
- You are younger than 18 or older than 40 years.
- You belong to a non-Caucasian race.
- You are living in poverty.
- You got pregnant while using an IUD, and it is left in place during the pregnancy.
- You were seriously underweight when you became pregnant.
- You smoke or use cocaine or other street drugs.
- You have had second-trimester miscarriages during previous pregnancies, or you have had three or more elective abortions.
- You are not receiving prenatal care from a qualified health-care provider.
- You have a cervical infection, such as group B streptococci, gonorrhea, chlamydia, syphilis, trichomonas or gardnerella.
- You are employed, doing extremely physical and strenuous work.
- Contractions (tightening and hardening of the uterus), occurring more than four per hour (may be painless).
- Low cramps, similar to menstrual cramps.
- Low backache.
- A feeling of pelvic pressure.
- Abdominal cramps, gas or diarrhea.
- A change in quality or quantity of vaginal discharge, especially any gush or leak of fluid.
Premature delivery may be preceded either by contractions or premature rupture of the fetal membranes (PROM), when the water breaks before labor begins. Although there have been many advances in caring for premature babies, there has been no improvement in solving the problem of preterm labor or PROM. We don't completely understand why some women go into labor or break their bag of water too early. We are often unable to accurately predict which women will do so, and we are limited in preventing these women from giving birth prematurely. In some cases, an infection may be involved; in others, it may be an abnormally short cervix or a combination of factors. In about half of all cases, no cause can be found. The number of babies born prematurely in the United States has actually risen in the last 10 years.
Diagnostic and Test Procedures
If you go to your health-care provider or a hospital because you think you may be in preterm labor, monitors will be placed on your abdomen to measure your baby's heart rate and record any uterine contractions that you have. The doctor will do a pelvic examination to check if your cervix is dilating. If you report that you think your water has broken or if the doctor sees any fluid coming from the cervix, he or she will take a small sample of fluid in order to determine whether it is truly amniotic fluid. If it is, a sample may be sent to a laboratory to determine how mature your baby's lungs are. Alternatively, your doctor may choose to perform an amniocentesis, which can provide information about your baby's lung development. Swabs of your cervix will be sent to a laboratory to test for infection, such as the presence of beta Strep. Your practitioner will want to test your urine for infection. You may be asked to provide a urine specimen, or your practitioner may put a tiny tube in your bladder (catheter) to remove a urine sample.
If you get to the hospital early in labor, your practitioner can stop labor from progressing with hydration, bed rest, muscle relaxants or other drugs, possibly requiring hospitalization. The intent is to stave off labor to allow the baby's lungs and other organs more time to develop and reach maturity. Furthermore, if doctors can prevent delivery for even a little while, the mother can be given steroids to speed up the baby's lung development.
If your health-care provider determines that you are in preterm labor, you may be admitted to the hospital. You'll probably be given intravenous fluids (through a needle in your arm). The most common medications used to stop or slow labor contractions are magnesium sulfate, ritodrine (the only FDA approved medication for premature labor) and terbutaline. A number of other medications are still being investigated for this use, including prostaglandin synthetase inhibitors (indomethacin), calcium-channel blockers, aminophylline and progesterone. You are often given an antibiotic prophylactically, even if you have no obvious infection. Also, you'll usually be given steroid medications to speed up your baby's lung development.
If your contractions are successfully stopped, you may be sent home from the hospital, sometimes with an oral medication. You'll probably be asked to decrease your activity level, or even to stay on bedrest, until you get closer to your due date.
Sometimes when you are in premature labor, your doctor may choose to allow you to deliver the baby early, rather than trying to stop labor. This choice is usually made when the mother is suffering from an infection of the amniotic fluid and uterus, or has illnesses such as severe preeclampsia or eclampsia (forms of high blood pressure that occur during pregnancy). Delivering the baby prematurely may also be preferable if fetal evaluation shows that the fetus is not doing well, if there is placenta previa (placenta covering the cervix) that bleeds a lot, if there is abruptio placentae (detachment of the placenta) or if certain birth defects or malformations are identified.
The most important thing you can do to try to have a healthy baby is to get early and adequate prenatal care. In fact, the best prenatal care begins even before you are pregnant. That way, you can be sure that you are in the best of health before pregnancy. Your practitioner will screen you for risk factors of premature delivery and discuss which precautions you could take. Measuring the length of the cervix using a special transvaginal ultrasound probe can predict a woman's risk of delivering prematurely. This is usually done in the doctor's office between 20 and 28 weeks of pregnancy. Researchers are studying vaginal secretions called cervicovaginal fetal fibronectin as a possible predictor of preterm labor. A woman at increased risk for premature delivery can be forewarned about what to do if symptoms occur, and may undergo further screening tests.
If you think that you broke your water, call your provider right away or go to the hospital. If you think that you are experiencing preterm contractions, you should stop what you are doing, go to the bathroom to empty your bladder, and then lie down on your left side. You should drink two glasses of water and juice, and try to relax. Many times, women are able to stop contractions by making sure that they are well hydrated and resting. If you continue to have four or more contractions per hour, call your health-care provider.
Call Your Doctor If:
- You are having at least four contractions every hour, even if they're painless.
- You have low, menstrual-like cramps.
- You have a low, dull, constant backache.
- You notice a change in your vaginal discharge, or a gush or slow leak of fluid from your vagina.
- You notice a sensation of pelvic pressure.
- You have abdominal cramping, gas or diarrhea.
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