Preterm labor is a difficult and often unpredictable event that can occur during pregnancy. It is defined as labor that begins before the 37th week of gestation. While the exact cause of preterm labor is unknown, there are certain risk factors that can increase the likelihood of it occurring. These include problems with the uterus or placenta, smoking cigarettes or using illicit drugs, certain infections, and chronic conditions such as high blood pressure, diabetes, autoimmune diseases, and depression.
Intrauterine infection is a common cause of preterm labor. This type of infection occurs inside the womb and can be caused by bacteria such as E. coli and group B streptococcus (GBS), as well as bacterial vaginosis, chlamydia, trichomoniasis, gonorrhea, syphilis, and HIV. If a woman has an intrauterine infection, it can lead to premature birth.
Additionally, if the cervix shortens during pregnancy, it may indicate that a woman is at risk for preterm labor. Premature membrane rupture before delivery (PPROM) is another potential cause of preterm labor. This occurs when the amniotic sac ruptures before 37 weeks of pregnancy. If you experience any signs of preterm labor such as contractions, increased vaginal discharge, bleeding, or pelvic pain, it is important to contact your healthcare provider right away.
In most cases, preterm births are medically induced (through induction or caesarean section) rather than occurring naturally in order to reduce the risk of complications. Preterm birth is difficult to avoid but there are some steps that can be taken to reduce the risk. If a woman has had a
spontaneous preterm birthat an early gestational age (between 20 and 32 weeks), the most common cause is usually an infection or inflammation. Even an infection or inflammation in the mother's gums and teeth (known as periodontal disease) can lead to premature birth.
A thorough review of a woman's medical history can also help determine the cause of a previous preterm birth. This should include information about the time and symptoms experienced during the preterm birth. Because many preterm babies are born with low birth weight, many risk factors for preterm birth are similar to those associated with having a baby with a low birth weight. If you have had a premature birth in the past, your healthcare provider may recommend medications to prevent you from going into labor too soon.
Additionally, if you are having a preterm birth your cervix may open sooner than usual.You may have an increased risk of having a preterm birth if you are pregnant with twins or if you have a history of preterm birth or preterm delivery. However, some preterm births occur when the mother has an abnormal or inflammatory response to normal vaginal or cervical bacteria.