The causes of preterm labor and birth are numerous, complex, and only partly understood. Medical, psychosocial, and biological factors all affect a woman's risk of preterm birth. There are three main reasons why preterm delivery and birth occur:
- Spontaneous preterm labor. This term refers to unintentional, unplanned delivery before the 37th week of pregnancy. Although the cause of spontaneous preterm labor and delivery is usually not known, a history of having one preterm birth is one of the strongest predictors for subsequent preterm births.1
- Medically indicated preterm birth. If a woman or the fetus has a serious medical condition, the doctor might recommend delivering the infant early.
- Non-medically indicated (elective) preterm delivery. Some late-preterm births result from inducing labor or having a C-section without a medical reason. The reasons for elective preterm delivery include: maternal discomfort during late stages of pregnancy, prior history of problems during labor or delivery, a suspicion that the fetus is larger than it should be at that stage of pregnancy, and such things as a desire to give birth on a certain date. Unless there are medical problems, women should wait until at least 39 weeks to schedule an induced labor or cesarean delivery to prevent possible prematurity-related problems in their infants.2 The risks to the infant are the same regardless of the reason for preterm delivery. It is important that the health care provider and the patient understand when it is a safe time for delivering the infant.
- American Congress of Obstetricians and Gynecologists, District II. (2009). Preventing preterm birth: The role of 17α hydroxyprogesterone caproate. Retrieved April 18, 2012, from https://www.acog.org/~/media/Announcements/20111013MakenaLtr.pdf (PDF - 1.84 MB) [top]
- March of Dimes. (n.d.). What is late-preterm birth? Retrieved April 18, 2012 from http://www.marchofdimes.com/research/prematurity-research.aspx [top]