RELATED STORIES • Preeclampsia • Ectopic pregnancy • Placental abruption • Placenta previa

Note: All links within content go to MayoClinic.com

Most babies are born about 40 weeks after the first day of their mother's last menstrual period. But about one in eight babies arrives sooner, according to the March of Dimes. A birth that takes place more than three weeks before the due date is considered a premature birth.

A premature birth gives a baby less time to develop and mature in the womb. The result is an increased risk of medical and developmental problems, including underdeveloped lungs. If you go into labor too early, your doctor may try to delay your baby's birth. Even a few extra days in the womb can promote significant development.

The rate of premature birth has grown by more than 30 percent in the last 20 years, according to the Institute of Medicine. Thankfully, a healthy lifestyle can go a long way toward preventing preterm labor and birth.

Prompt recognition of preterm labor may help you prevent premature birth. Even months before your due date, be on the lookout for:

• Regular contractions of your uterus (You'll feel a tightening sensation in your lower abdomen, often reminiscent of menstrual cramps.)
• Low, dull backache
• A sensation of pelvic pressure
• A tightening sensation in the thighs
• Vaginal spotting or bleeding
• Watery vaginal discharge (This may be amniotic fluid, which surrounds your baby in the womb. A leakage may indicate that the membranes around your baby have ruptured.)

If you suspect you're in preterm labor but haven't had a watery discharge, stop what you're doing and rest. Pay attention to what you're feeling. If you have regular contractions 10 minutes apart or less, contact your doctor or go to the hospital. If you're having contractions but they're irregular or more than 10 minutes apart, drink two or three glasses of water and lie down on your left side. This helps improve circulation to your uterus and may stop contractions.

Some women who go into preterm labor do so for unknown reasons. Other women may have a medical condition that contributes to early labor, such as:

• Ruptured amniotic sac. Normally, the fluid-filled sac that surrounds your baby in the womb ruptures during labor or just before labor begins. But sometimes the sac may rupture for no apparent reason weeks or even months before your due date. In that case, there's a high risk that labor will begin within a few days. A ruptured amniotic sac also increases the risk of infection for both you and your baby.
• Certain infections. Infections of the cervix or urinary tract are associated with preterm rupture of the membranes and preterm labor.
• Weak cervix. In a normal pregnancy, the cervix softens late in pregnancy and opens (dilates) in response to uterine contractions. But for some women, the cervix opens earlier — perhaps due to the weight of the baby and amniotic fluid. This problem can be associated with previous surgery involving the cervix, such as a dilation and curettage (D and C) or a cone biopsy. It's somewhat more likely to occur when you're pregnant with twins or other multiples.
• Certain chronic diseases. Diseases such as high blood pressure, diabetes, kidney disease and lupus may increase the risk of preterm labor. If complications arise, labor may need to be induced early.
• Uterine abnormalities. An abnormally shaped uterus may increase the risk of preterm labor.
• A previous premature delivery. Women who've had a premature delivery are at higher risk of preterm labor. For many women, though, early labor happens only once.
• Substance abuse. These include smoking, drinking alcohol or using illicit drugs.
• Malnutrition. Women who are undernourished or anemic are more likely to give birth prematurely.
• Excess amniotic fluid. Too much amniotic fluid can contribute to early labor.

Good prenatal care includes regular visits to your doctor throughout your pregnancy to check on both your health and your baby's health. If you're at risk of preterm labor, your doctor may recommend more frequent visits.

If you develop any signs or symptoms of early labor — such as bleeding with cramps and pain, a watery vaginal discharge or regular contractions 10 minutes apart or less — call your doctor or hospital right away. It's a good idea to keep these phone numbers handy so that you can find them quickly.

If preterm labor seems likely, your doctor will check to see if your cervix has begun to dilate and whether the fetal membranes have ruptured. The duration and spacing of your contractions may be closely monitored. In some cases, your doctor may use ultrasound to monitor the length of your cervix. A swab from the cervical canal may be tested for the presence of fetal fibronectin, a glue-like tissue lost during labor.

If you're in preterm labor, you and your doctor will discuss the risks and benefits of trying to stop your labor.

Preterm labor and birth may have various complications.

For mothers
Preterm labor doesn't pose greater physical risks than later labor, unless it's the result of another problem — such as a uterine infection. But all treatments used to delay delivery carry some risks.

Medications that halt uterine contractions may cause fluid to collect in your lungs, which can make it difficult to breathe. Other side effects depend on the medication used to stop labor. Some medications can lead to fatigue and muscle weakness. Others may cause a rapid heart beat, blood sugar abnormalities or stomach ulcers.

You and your doctor will need to consider your own potential risks from medications used to stop labor, as well as possible risks to your baby if he or she is born too soon.

For babies
If your baby is premature, how well he or she will thrive depends largely on gestational age at birth. Risks are greatest for the youngest babies.

Survival is possible for babies born as early as 23 to 26 weeks, but these preemies may face a lifetime of health problems — including cerebral palsy, fluid accumulation in the brain (hydrocephalus), seizures, lasting neurological problems or developmental delays. Others will have less serious chronic problems, such as vision problems or mild developmental delays.

Premature babies are also at risk of other conditions:

• Bleeding in the brain (intracranial hemorrhage). If this occurs, it's usually in the first week to 10 days of life. The more severe the bleeding, the greater the likelihood that the child will develop serious problems, including developmental delays, seizures, learning disabilities and fluid accumulation in the brain.
• Retinal problems. Another complication seen in the youngest and most vulnerable premature babies is retinopathy of prematurity (ROP), an abnormal growth of blood vessels in the retina — the light-sensitive inner lining of the eye. ROP probably occurs because the vascular system in the baby's eye hasn't fully developed. Many cases of ROP improve on their own, but the condition can lead to scarring or some degree of vision impairment. The most serious cases may be treated with laser surgery to help prevent retinal detachment.
• Intestinal problems. Preemies also have an increased risk of a potentially severe intestinal problem known as necrotizing enterocolitis (NEC). In the most serious cases, this condition can be life-threatening. Infants who have NEC need to be fed intravenously and given antibiotics.
• Sudden infant death syndrome (SIDS). Premature babies have a higher risk of SIDS, the sudden and unexplained death of an infant during sleep.

For some premature babies, difficulties may not appear until later in childhood. Not performing well in school is often a prime concern.

But not all preemies have medical or developmental problems. By 28 to 30 weeks, the risk of serious complications is much lower. And for babies born between 32 and 35 weeks, most medical problems are short-term.

Treatment may focus on women in preterm labor, on babies still in the womb or on newborns in hospital neonatal (newborn) intensive care units (NICUs).

For mothers
If you're experiencing preterm labor, treatment depends on your stage of pregnancy and how far labor has progressed. Sometimes bed rest and extra fluids are enough to stop premature contractions.

If you have a weak cervix early in pregnancy, a surgical procedure known as cervical cerclage may help prevent preterm labor. Using strong sutures, your doctor stitches the cervix closed. The sutures are removed in the last month of pregnancy.

In other cases, your doctor may recommend medication. These may include terbutaline (Brethine), a medication that relaxes smooth muscles — including those of the uterus — or the muscle relaxant magnesium sulfate. Sometimes medications that block the calcium channels in muscle cells can stop contractions. So can drugs that block the production of substances that stimulate uterine contractions (prostaglandins), such as ibuprofen (Advil, Motrin, others) or indomethacin (Indocin).

Medications often stop labor only briefly, however — perhaps long enough to accomplish other goals, such as transferring you to a facility better equipped to care for a premature baby or allowing use of other medications that have a beneficial effect on the baby.

For babies in the womb
If preterm delivery is likely, you may be given medications to help prepare your baby for birth. Corticosteroids such as betamethasone and dexamethasone can help speed your baby's lung maturity in as little as 24 to 48 hours. After week 34, steroids aren't typically needed because lung development is more advanced.

For newborns
Hospital NICUs are designed to provide care for premature babies and full-term babies who develop serious problems after birth. In the NICU, babies receive round-the-clock intensive care from doctors, nurses and respiratory therapists specially trained to care for newborns with medical problems.

In the NICU, your baby will probably be kept in an incubator — an enclosed plastic bassinet that's kept warm to help your baby maintain normal body temperature. Because preemies have immature skin and very little body fat, they often need such care to stay warm.

Sensors may be taped to your baby's body to monitor blood pressure, heart rate, breathing and temperature. Caregivers may also use ventilators to help your baby breathe. This high-tech equipment may seem overwhelming at first, but it's all designed to help your baby.

At first your baby may receive fluids and nutrients through an intravenous tube. Milk feedings may be given later through a tube passed through your baby's nose and into his or her stomach. When your baby is strong enough to suck, breast-feeding or bottle-feeding is often possible. The antibodies in breast milk are especially important for premature infants.

Your baby's caregivers will help you learn how to touch and eventually hold and feed your baby. Talking or singing softly to your baby, or just providing quiet company, can give great support and comfort.

Taking your baby home
Premature babies are ready to go home when they no longer require continuous hospital care, when their body temperature is stable at room temperature and when they feed well enough to gain weight. Your baby need not reach a specific weight or age before going home.

Your baby's doctor will provide guidelines on how to care for your baby at home. Keep in mind that preemies are more susceptible than are other newborns to serious infections, and their illnesses tend to progress more quickly. Schedule frequent checkups for your baby. Routine checkups are a great time to ask questions about caring for your baby.

A healthy lifestyle can go a long way toward preventing preterm labor and birth.

• Seek regular prenatal care. Mention any signs or symptoms that concern you, even if they seem unimportant.
• Eat healthy foods. During pregnancy, you'll need more folic acid, calcium, iron, protein and other essential nutrients. A daily prenatal vitamin — ideally starting before conception — can help fill any gaps.
• Manage chronic conditions. Remember, uncontrolled diseases such as diabetes and high blood pressure increase the risk of preterm labor. Work with your doctor to keep any chronic conditions under control.
• Limit stress. Set reasonable limits — and stick to them. Set aside some quiet time every day. Ask for help when you need it.
• Follow your doctor's guidelines for activity. If there are problems with your pregnancy, your doctor may suggest working fewer hours or spending less time on your feet. Sometimes it makes sense to scale back other physical activities, too.
• Ask your doctor about sex. Sex may be off limits if you have certain complications — such as vaginal bleeding or problems with your cervix or placenta.
• Avoid risky substances. Smoking may trigger preterm labor. Alcohol and recreational drugs are off limits, too. Even over-the-counter supplements and medications deserve caution. Get your doctor's OK before taking any medications or supplements.

Some research suggests that the hormone progesterone may prevent preterm labor in women at high risk. If you're a candidate for this treatment, your doctor may recommend weekly progesterone injections. Although promising, the effectiveness of progesterone treatments in preventing preterm labor isn't yet clear.

It's also important to take care of your teeth. Although a 2006 study found that treating gum disease by cleaning the teeth above and below the gums doesn't reduce the risk of premature birth — negating the recent association between gum disease and premature birth — good dental hygiene remains an important part of proper prenatal care.

Caring for a premature infant can be a great challenge. You may be anxious about your baby's health and the long-term effects of premature birth. You may also feel angry or guilty. Sudden hormonal changes after pregnancy may trigger anxiety or postpartum depression.

You may find it hard to establish milk production if your baby is too small or requires too much support to breast-feed at first, and you may need more time to recover physically than you expected. Fatigue is inevitable. Long hours in the hospital with your baby are exhausting, and caring for a preemie at home may leave you little time to rest.

Some of these suggestions may help during this difficult time:

• Learn everything you can about your baby's condition. In addition to talking to your baby's doctor and other caregivers, read books on premature birth and look for information on the Internet.
• Take care of yourself. Get as much rest as you can and eat healthy foods. You'll feel stronger and better able to care for your baby.
• Establish your milk supply. Use a breast pump until your baby is able to breast-feed. Ask the hospital staff for help, if needed.
• Seek good listeners for support. Talk to your partner or spouse, friends, family or your baby's caregivers. If you're interested, your baby's caregivers may be able to suggest a support group in your area. Many parents find it particularly helpful to talk to other parents who are caring for a preemie.
• Accept help from others. Allow friends and family to help you. They can care for your other children, prepare food, clean the house or run errands. This helps you save your energy for your baby.
• Keep a journal. Record the details of your baby's progress as well as your own thoughts and feelings. Include pictures of your baby so that you can see how much he or she changes from week to week.