Preterm Labour

What Happens

If preterm labour occurs close to your due date (in the 35th or 36th week of pregnancy), you may be allowed to deliver without delay. Preterm birth at this point in a pregnancy usually results in few or no serious complications.

Symptoms of preterm labour are a warning sign. They do not necessarily mean that preterm birth is inevitable. Of all women who see a health professional about their preterm contractions (before 37 weeks, without preterm premature rupture of membranes (PROM), about half will deliver at full term.⁴

If preterm labour contractions do not stop, the cervix may thin (efface) and open (dilate). The amniotic sac may break (rupture), leading to preterm birth.

The method of delivery used in premature labour depends on the health of the mother and fetus. In most cases a woman can deliver vaginally. If the health of the mother or fetus is at risk, a caesarean section may be needed. See the topic Pregnancy for more information.

Sometimes a pregnancy poses a great enough health risk to a mother or her fetus that it is necessary to deliver by caesarean or induce labour for a preterm vaginal delivery. This is called an indicated preterm birth, accounting for about 25% of preterm births.⁵

Premature infant

The more prematurely an infant is born, the greater the risk of medical complications of prematurity. A premature fetus's likelihood of survival increases as the pregnancy advances and as the fetus gains weight. The fetus's stage of development, ability to breathe (lung maturity), and overall health are also important factors for survival. Because of advances in medical care, more premature infants are surviving today than in years past. For more information, see the topic Premature Infant.

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Author:	Kathe Gallagher, MSW Carrie Henley	Last Updated: April 10, 2007
Medical Review:	Joy Melnikow, MD, MPH - Family Medicine Anne C. Poinier, MD - Internal Medicine Gregory A L Davies, MD, FRCSC, FACOG - Maternal-Fetal Medicine William Gilbert, MD - Perinatology
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