Preterm labor, which occurs when labor begins before 37 weeks of pregnancy, can be caused by a variety of factors involving the pregnant person, the baby, or both. Often, no specific cause is identified, but known causes and risk factors include:
- Infections: Infections of the uterus, amniotic fluid, urinary tract, or lower genital tract can trigger preterm labor
- Multiple pregnancies: Carrying twins, triplets, or more increases the risk due to uterine stretching and other factors
- Chronic medical conditions: Conditions such as high blood pressure, diabetes, autoimmune diseases, and depression can contribute
- Uterine or cervical problems: A short or incompetent cervix, uterine abnormalities (e.g., bicornuate uterus), or previous uterine surgery increase risk
- Placental issues: Placental abruption or placenta previa can lead to preterm labor
- Lifestyle factors: Smoking, drug or alcohol use, poor nutrition, and lack of prenatal care raise the risk
- Pregnancy-related factors: Too much amniotic fluid (polyhydramnios), vaginal bleeding during pregnancy, short intervals between pregnancies (less than 6-18 months), and pregnancies conceived via assisted reproductive technology
- Demographic factors: Maternal age under 17 or over 35, certain racial and ethnic groups (e.g., African American, American Indian/Alaska Native), and low socioeconomic status are associated with higher risk
- Stress and social factors: Stressful life events, domestic violence, and long work hours may contribute
In many cases, a combination of these factors is involved, and sometimes the cause remains unknown
. Thus, preterm labor is multifactorial, with infections, multiple gestations, chronic conditions, uterine or cervical issues, lifestyle, and social determinants playing key roles. Regular prenatal care is crucial to monitor and manage these risk factors to support a full-term pregnancy
