Preventing preterm labor involves a combination of lifestyle choices, medical monitoring, and, when needed, specific interventions that your healthcare provider can offer. Most strategies focus on reducing known risk factors and catching warning signs early enough to act. While no single approach guarantees you’ll carry to full term, understanding what actually works (and what doesn’t) puts you in the strongest position possible.
Risk Factors You Can Change
Several modifiable risk factors are directly linked to spontaneous preterm birth. Addressing them won’t eliminate risk entirely, but each one you manage tips the odds in your favor:
- Smoking, alcohol, and drug use all independently increase the chance of early labor. Quitting at any point during pregnancy reduces risk.
- Infections like urinary tract infections, bacterial vaginosis, and sexually transmitted infections can trigger preterm contractions. Getting screened and treated early matters.
- Chronic stress and lack of social support are recognized risk factors. This includes intimate partner violence.
- Long working hours with extended periods of standing are associated with higher preterm birth rates.
- Poor nutrition and late or absent prenatal care round out the list of factors within your control.
None of these are guarantees of preterm labor on their own. But in combination, they create a profile that makes early delivery more likely. The earlier in pregnancy you address them, the better.
Staying Hydrated Matters More Than You Think
Dehydration can directly increase uterine activity. When your blood volume drops, blood flow to the uterus decreases, which can destabilize tissue in the uterine lining and increase production of prostaglandins, compounds that stimulate contractions. Dehydration may also cause your body to release more oxytocin, the hormone responsible for labor contractions.
Drinking enough water throughout the day does the opposite: it expands blood volume, improves uterine blood flow, and may suppress the hormonal signals that trigger contractions. If you’re experiencing irregular tightening or mild contractions, drinking a large glass of water and resting is a reasonable first step before calling your provider. Many episodes of increased uterine activity resolve with hydration alone.
Bed Rest Is Not Recommended
For decades, bed rest was a standard prescription for women at risk of preterm labor. Current guidelines from the American College of Obstetricians and Gynecologists are clear: activity restriction should not be routinely prescribed to reduce preterm birth. The evidence simply doesn’t support it, and prolonged bed rest carries its own risks, including blood clots, muscle loss, and psychological effects. Your provider may still recommend reducing specific high-intensity activities, but blanket bed rest is no longer considered effective prevention.
Cervical Length Screening
One of the strongest predictors of preterm birth is the length of your cervix. A short cervix means the cervix is thinning or opening earlier than it should. Measured by transvaginal ultrasound, a cervical length of 25 millimeters or less at around 24 weeks of gestation carries a six-fold increased risk of preterm delivery. When the cervix measures under 15 millimeters, the risk jumps dramatically: in one study, women with a cervix that short accounted for 86% of births before 28 weeks.
If you have risk factors for preterm birth, your provider may recommend cervical length screening during mid-trimester ultrasounds. This is a quick, painless measurement that can identify problems before symptoms appear, giving you and your care team time to intervene.
Cervical Cerclage
A cerclage is a stitch placed around the cervix to hold it closed. It’s typically offered in three situations: when you have a history of two or more second-trimester losses from painless cervical dilation, when ultrasound reveals a short cervix (under 25 mm) in someone with prior preterm birth, or when a physical exam finds the cervix already dilating without symptoms during mid-pregnancy.
The procedure is most effective when placed early based on history or ultrasound findings. In those groups, delivery before 28 weeks occurred in roughly 6 to 10% of cases. When the cerclage was placed after the cervix had already begun opening significantly, the rate of delivery before 28 weeks jumped to 33%, and delivery before 34 weeks reached 60%. The timing matters enormously. Overall, research shows higher fetal survival rates in patients who receive a cerclage compared to those managed with observation alone.
Progesterone Treatment
Progesterone supplementation has been widely studied for preterm birth prevention, and the picture is more nuanced than many patients expect. For women with a shortened cervix, vaginal progesterone may offer benefit. However, recent meta-analyses found that vaginal progesterone does not reduce recurrent preterm birth in women who have a normal cervical length, even if they’ve had a prior preterm delivery.
An injectable form of progesterone (known as 17-OHPC) was once routinely given to women with a history of preterm birth. The FDA reviewed the available evidence and concluded there wasn’t sufficient data to support its effectiveness across the broad population it was approved for. Current ACOG guidance recommends against using injectable progesterone as a primary prevention strategy for recurrent preterm birth. Your provider may still discuss progesterone in specific clinical scenarios, particularly if you have a documented short cervix.
The Fetal Fibronectin Test
If you’re experiencing symptoms that worry you, one of the most useful tools is a fetal fibronectin (fFN) test. Fibronectin is a protein that acts like a biological glue between the amniotic sac and the uterine lining. A swab test can detect whether this protein is present in vaginal secretions. The real power of this test is its negative result: a negative fFN test has a 100% negative predictive value for delivery within 7 days, in both singleton and multiple pregnancies. That means if the test comes back negative, you are not going to deliver in the next week. This can save you from unnecessary hospitalization and medications, and provide significant peace of mind.
Telling Real Contractions From Braxton Hicks
One of the most anxiety-producing parts of pregnancy is figuring out whether what you’re feeling is harmless practice contractions or the start of actual labor. Braxton Hicks contractions are irregular, don’t get closer together over time, and tend to stay weak or fade away on their own. They’re usually felt in one specific spot on the front of the abdomen and often stop when you change position, take a walk, or lie down. If you can sleep through them, they’re almost certainly Braxton Hicks.
True preterm labor contractions follow a different pattern. They come at regular intervals and get progressively closer together, longer in duration, and stronger in intensity. They typically start in the mid-back and wrap around toward the front of your abdomen. Changing positions or moving around doesn’t relieve them. If you notice four or more contractions in an hour that follow this pattern, especially before 37 weeks, contact your provider.
Other warning signs of preterm labor include a change in vaginal discharge (watery, mucus-like, or bloody), constant low backache, pelvic pressure that feels like the baby is pushing down, and abdominal cramping with or without diarrhea.
What Happens If Preterm Labor Starts
If you do go into preterm labor, the immediate medical goal is usually to delay delivery by 48 hours. Medications called tocolytics can quiet uterine contractions and buy this critical window of time. They work by relaxing the uterine muscle through various mechanisms and can typically delay birth by two to seven days. The 48-hour window is particularly important because it allows time for corticosteroid injections to take effect.
A single course of corticosteroids is recommended for pregnancies between 24 and 34 weeks when delivery appears likely within 7 days. These steroids rapidly accelerate fetal lung development, dramatically improving outcomes if the baby is born early. A repeat course may be considered if the first was given more than 14 days earlier and preterm delivery still appears imminent. The combination of tocolytics to delay labor and steroids to mature the baby’s lungs is one of the most well-established interventions in obstetric care.