Alternate Names : Preterm Labor
In most pregnancies, labor starts at about 40 weeks. Labor that starts before the end of the 37th week is considered preterm. Preterm labor can lead to preterm birth. About 1 in every 10 babies born in the United States is born preterm. Preterm birth accounts for 3 of every 4 newborn deaths that are not related to birth defects.
What is going on in the body?
Labor starts with regular contractions of the uterus. The cervix thins out and dilates, or opens up, so the baby can enter the birth canal. Sometimes labor begins earlier than it should. If preterm labor is caught quickly, delivery can often be postponed. This gives the baby extra time to grow and mature. Growth and development in the last part of pregnancy are critical to the baby's health. A baby born too early is at risk for fetal distress.
If a preterm delivery seems likely, the healthcare provider will try to determine if the baby's lungs are mature enough to survive outside the uterus. If the lungs are not mature enough, the baby may develop respiratory distress syndrome. This is the most common cause of death in preterm babies.
What are the causes and risks of the condition?
In 50 to 60% of preterm labors, the cause is not known. The factors known to cause preterm labor can be divided into major and minor ones.
history of preterm labor or birth
two previous second-trimester abortions
defects in the uterus such as an incompetent cervix, fibroids, or double uterus
excess amniotic fluid
abdominal surgery during pregnancy
birth defects in the fetus
one previous second-trimester abortion
three previous first-trimester elective abortions
bleeding after 12 weeks
weight less than 100 pounds
any illness with fever
smoking more than 10 cigarettes a day
high blood pressure
chronic illness, such as diabetes