Tests and diagnosis

By Mayo Clinic Staff

To help diagnose preterm labor, your health care provider will document your signs and symptoms. If you're experiencing regular, painful contractions and your cervix has begun to soften, thin and open before 37 weeks of pregnancy, you'll likely be diagnosed with preterm labor.

Tests and procedures to diagnose preterm labor include:

  • Pelvic exam. Your health care provider might evaluate the firmness and tenderness of your uterus and the baby's size and position. He or she might also do a pelvic exam to determine if your cervix has begun to open — if your water hasn't broken and the placenta isn't covering your cervix (placenta previa).
  • Ultrasound. An ultrasound might be used to measure the length of your cervix and determine your baby's size, age, weight and position in your uterus. You might need to be monitored for a period of time and then have another ultrasound to measure any changes in your cervix, including cervical length.
  • Uterine monitoring. Your health care provider might use a uterine monitor to measure the duration and spacing of your contractions.
  • Lab tests. Your health care provider might take a swab of your vaginal secretions to check for the presence of certain infections and fetal fibronectin — a substance that acts like a glue between the fetal sac and the lining of the uterus and is discharged during labor. However, this test isn't reliable enough to be used on its own to assess the risk of preterm labor.
  • Maturity amniocentesis. Your health care provider might recommend a procedure in which amniotic fluid is removed from the uterus (amniocentesis) to determine your baby's lung maturity. The technique can also be used to detect an infection in the amniotic fluid.

If you're in preterm labor, your health care provider will explain the risks and benefits of trying to stop your labor. Keep in mind that preterm labor sometimes stops on its own.

Oct. 19, 2016