Preterm Birth
Birth that happens before 37 weeks of pregnancy
Quick Facts
- Type: Pregnancy and newborn condition
- Definition: Birth before 37 completed weeks
- Key concern: Organs may be underdeveloped
- Warning signs: Regular contractions, fluid leak, pelvic pressure before 37 weeks
Overview
Preterm birth is delivery that occurs before 37 completed weeks of pregnancy. A full-term pregnancy lasts about 40 weeks, and the last weeks are an important time for a baby's lungs, brain, and other organs to mature. Babies born early, especially well before term, may need extra medical care because these organs are not yet fully developed.
Preterm birth can follow spontaneous preterm labor, the early breaking of the waters, or a planned early delivery when continuing the pregnancy would be unsafe for the mother or baby. Knowing the warning signs of preterm labor and attending regular prenatal care help with early recognition and treatment.
Signs of Preterm Labor
Preterm labor is labor that begins before 37 weeks. Warning signs include:
- Regular or frequent tightening or contractions of the abdomen
- A constant low, dull backache
- Pelvic pressure or a feeling that the baby is pushing down
- Mild abdominal cramps, with or without diarrhea
- A change in vaginal discharge, or a gush or trickle of fluid (the waters breaking)
- Light vaginal bleeding or spotting
Anyone experiencing these signs before 37 weeks should contact their maternity care provider promptly, as early treatment may help.
Causes
Preterm birth often has no single identifiable cause, but several factors are associated with it.
- Infections: Infections of the uterus, urinary tract, or other areas.
- Problems with the cervix or uterus: A weakened cervix or abnormalities of the uterus.
- Multiple pregnancy: Carrying twins or more.
- Pregnancy complications: High blood pressure, preeclampsia, or problems with the placenta or amniotic fluid.
- Maternal health conditions: Diabetes and other chronic illnesses.
Sometimes an early delivery is planned by the medical team because it is safer than continuing the pregnancy.
Risk Factors
- A previous preterm birth
- Carrying twins, triplets, or more
- Problems with the cervix, uterus, or placenta
- Infections during pregnancy
- High blood pressure, diabetes, or preeclampsia
- Smoking, alcohol, or substance use during pregnancy
- Short interval between pregnancies and being underweight or overweight
Diagnosis
When preterm labor is suspected, providers assess how close birth may be.
- Examination: Checking the cervix for opening and softening.
- Monitoring contractions: Measuring the frequency and strength of contractions and the baby's heart rate.
- Ultrasound: To measure cervical length and assess the baby and fluid.
- Tests of vaginal fluid: To check for ruptured membranes or markers that help predict the likelihood of early labor.
- Screening for infection: Urine and other tests as needed.
Treatment
Management aims to delay birth when safe and to prepare the baby for an early arrival.
- Medications to slow labor: Drugs may be used short term to delay delivery and allow time for other treatments.
- Steroids: Given to the mother to help the baby's lungs and other organs mature.
- Magnesium sulfate: May be used to help protect the baby's brain in very early labor.
- Antibiotics: When infection is present or the waters have broken.
- Specialized newborn care: Babies born early may need care in a neonatal unit.
In some situations, the safest course is to proceed with delivery, and the team plans care for both mother and baby.
Prevention
- Attend all prenatal appointments
- Avoid smoking, alcohol, and recreational drugs during pregnancy
- Treat infections promptly and manage chronic conditions like diabetes and high blood pressure
- Discuss preventive options if you have had a previous preterm birth or a short cervix
- Maintain good nutrition and follow your provider's advice on activity
When to Seek Care
Contact your maternity care provider right away, or seek urgent care, if before 37 weeks you have:
- Regular or frequent contractions or tightening
- A gush or steady trickle of fluid from the vagina
- Pelvic pressure or a constant low backache
- Vaginal bleeding
- A noticeable decrease in the baby's movements
Prompt assessment allows treatments that may delay birth or protect the baby to be started in time.
Frequently Asked Questions
What counts as a preterm birth?
Preterm birth is delivery before 37 completed weeks of pregnancy. A full-term pregnancy lasts about 40 weeks, and the earlier a baby is born, the more likely it is to need extra medical support because organs may not be fully developed.
What are the warning signs of preterm labor?
Signs before 37 weeks include regular or frequent contractions, a constant low backache, pelvic pressure, abdominal cramps, a change in vaginal discharge or a gush of fluid, and light bleeding. Contact your maternity provider promptly if these occur.
Can preterm birth be prevented?
Not all preterm births can be prevented, but attending prenatal care, avoiding smoking and alcohol, treating infections, and managing conditions like diabetes and high blood pressure can lower risk. People with a previous preterm birth may be offered specific preventive options.
What happens to babies born preterm?
Many premature babies do well, but those born well before term may need care in a neonatal unit to support breathing, feeding, and temperature. Outcomes generally improve the closer a baby is born to full term.
What should I do if I think I am in preterm labor?
Contact your maternity care provider or seek urgent care immediately if you have signs of preterm labor before 37 weeks. Early assessment allows treatments such as medications to slow labor and steroids to help the baby's lungs to be started in time.
References
- Centers for Disease Control and Prevention (CDC). Preterm birth.
- Mayo Clinic. Premature birth — Symptoms and causes.
- MedlinePlus, U.S. National Library of Medicine. Premature babies.
- World Health Organization (WHO). Preterm birth.