Approximately 12 percent of babies born in the United States are premature, according to 2007 information from the American Pregnancy Association. Often there are no complications, but premature births increase the risk of certain medical conditions and developmental problems due to incomplete growth and development. There are many causes of premature births, but in many cases, the exact cause is unknown.
Premature Births
A normal pregnancy lasts approximately 40 weeks ,while a premature birth is defined as a birth occurring before 37 weeks of pregnancy. Pregnancy is an important time of growth and development for a baby and more time in the womb increases the chance of a healthy baby. The earlier a baby is born, the higher the risk of complications. According to the American Pregnancy Association, babies born before 24 weeks have a 50 percent survival rate, but those born after 34 weeks have a high rate of survival with no long-term complications.
PROM
Spontaneous premature rupture of the membranes, or PROM, is a common cause of premature births. It occurs when the amniotic sac that holds a baby inside the uterus breaks open shortly before labor resulting in a premature birth. An infection of the vagina, amniotic fluid or fetal membranes, or too much amniotic fluid are common causes of PROM, but in many situations, the exact cause is unknown, according to the March of Dimes website. Premature rupture of the membranes is more common in women with twins or multiples.
Cervical and Uterine Abnormalities
The cervix is the lower portion of the uterus that extends into the vagina. In pregnant women, it is designed to remain closed and hard until the birthing process begins, at which time it softens and widens during contractions to allow the baby to pass. However, in some women, the cervix is abnormally weak or short, a condition medically defined as cervical insufficiency. In this case, as the baby grows, it pushes on the cervix causing it to open too soon, leading to a premature birth.
Certain uterine abnormalities can also lead to premature births. A plethora of abnormalities exist from growths or polyps to structural irregularities of the uterus. The majority of these result in a uterine cavity that is smaller than normal, allowing less space for a baby to grow. In turn, as the baby grows, the womb is overstretched and labor is induced, according to Healthnews.com.
Complications
Premature births increase the risk of complications and the risk goes up the earlier the baby is born. Babies born before 36 weeks of pregnancy are considered to have immature lungs, according to the American Pregnancy Association. This increases the risk of respiratory distress syndrome, bronchopulmonary dysplasia, irregular breathing and pneumonia. Babies born prematurely are also at an increased risk of infection, slow heart rate, or bradycardia, jaundice and anemia. Babies born before 34 weeks of gestation have an increased risk of bleeding in the brain, a condition called intraventricular hemorrhage, according to the American Pregnancy Association.
Risk Factors
Medical conditions such as recurring bladder or kidney infections, sexually transmitted diseases or being under or overweight before pregnancy can increase the risk for a premature baby. High blood pressure, kidney disease and diabetes also increase the risk. Certain lifestyle choices increase the risk of a premature birth, such as little or no prenatal care, alcohol and illegal drug use, smoking, domestic violence and high stress environments, according to the American Pregnancy Association.
