Reducing your risk of preterm labor involves a combination of nutrition, stress management, infection prevention, and physical adjustments during pregnancy. Preterm birth, defined as delivery before 37 weeks, affects roughly 4 to 16% of pregnancies worldwide, with an estimated 13.4 million babies born early in 2020 alone. While some risk factors like genetics or a history of preterm delivery can’t be changed, several evidence-backed strategies can meaningfully lower your chances.
Omega-3 Fatty Acids and Preterm Birth Risk
One of the strongest nutritional links to preterm birth prevention involves omega-3 fatty acids, specifically the types found in fatty fish like salmon, sardines, and mackerel. A statement from the International Society for the Study of Fatty Acids and Lipids recommends a combined intake of about 1,000 mg of DHA plus EPA daily for women at risk of early delivery, ideally starting before 20 weeks of gestation. If you don’t eat fish regularly, a high-quality fish oil supplement can fill the gap. This isn’t a small effect: the evidence is strong enough that major nutrition bodies now include it in their formal guidance for pregnancy.
Why Your Weight Before and During Pregnancy Matters
Starting pregnancy underweight (a BMI below 18.5) nearly doubles the risk of preterm birth compared to women in the normal BMI range. For very early preterm delivery, that risk jumps even higher, with underweight women facing 2.3 times the odds. But here’s the encouraging part: underweight women who gained weight at a normal rate during pregnancy saw their preterm birth risk drop to nearly the same level as normal-weight women.
Very low weight gain during pregnancy, less than about a third of a pound per week, raised the risk across all weight categories. For underweight women with very low weight gain, the odds of spontaneous preterm birth were 3.4 times higher than normal-weight women gaining at a healthy pace. Eating enough calories and gaining steadily throughout pregnancy is one of the most straightforward things you can do to protect against early delivery.
How Chronic Stress Triggers Early Labor
Stress doesn’t just feel bad during pregnancy. It activates a biological chain reaction that can push labor to start too soon. When you’re under chronic stress, your body produces elevated levels of cortisol. During pregnancy, the placenta produces a hormone called corticotropin-releasing hormone (CRH), which further stimulates cortisol production. In a normal pregnancy, rising fetal cortisol near the due date helps shift the balance of hormones that initiates labor. But when maternal cortisol stays elevated for weeks or months, the fetus may be exposed to those labor-triggering signals far too early.
This process also works in the other direction. High cortisol can suppress your immune system enough to make you more vulnerable to infections in the uterus, and those infections produce inflammatory molecules that independently push the body toward labor. Stress and infection essentially feed each other in a loop that accelerates the timeline.
What actually helps reduce cortisol during pregnancy varies from person to person, but the research consistently points to regular moderate exercise, adequate sleep, and social support as protective. If you’re dealing with anxiety, depression, or an overwhelming life situation, addressing that directly with a therapist or counselor is a legitimate medical intervention for your pregnancy, not a luxury.
Gum Health and Preterm Birth
This one surprises most people. Periodontal disease, the chronic inflammation and infection of gum tissue, has a direct biological connection to preterm labor. In women with gum disease, the infected tissue acts as a reservoir of bacteria that can travel through the bloodstream to the placenta. One species in particular has been found in the amniotic fluid of premature births with no other obvious cause of early labor.
The mechanism works two ways. First, the bacteria themselves can colonize placental tissue. Second, the constant low-grade inflammation from gum disease raises systemic levels of inflammatory molecules that stimulate uterine contractions. Pregnancy hormones, especially progesterone and estrogen, actually feed certain oral bacteria, which is why many women notice their gums bleed more during pregnancy even without changes in brushing habits.
Getting a dental cleaning and addressing any gum inflammation early in pregnancy, or ideally before conception, is a simple step with real protective value. Brush twice daily, floss, and don’t skip dental visits because you’re pregnant.
Silent Urinary Tract Infections
Between 2 and 10% of pregnant women have bacteria growing in their urine without any symptoms at all, a condition called asymptomatic bacteriuria. Left untreated, these silent infections can progress to kidney infections, which carry serious risks including preterm birth, sepsis, and anemia. The American College of Obstetricians and Gynecologists recommends that every pregnant woman be screened with a urine culture early in prenatal care for exactly this reason.
Studies show that screening for and treating these silent infections reduces both kidney infections and preterm delivery. This isn’t something you can prevent on your own, but you can make sure it gets caught: keep your early prenatal appointments, and if your provider hasn’t mentioned a urine culture, ask about it. Staying well hydrated and urinating frequently also help reduce bacterial buildup, though they’re no substitute for screening.
Physical Activity and Occupational Risks
Moderate exercise during pregnancy is protective, not harmful. Walking, swimming, and prenatal yoga support healthy weight gain, reduce stress hormones, and improve circulation. What does raise concern is strenuous occupational physical activity, particularly heavy lifting and prolonged standing.
A large systematic review of workplace risks found that lifting more than 5 kg at a time (about 11 pounds) or standing for more than 3 hours per day at work were both associated with higher rates of preterm birth. Some individual studies found dramatic increases: one reported that heavy lifting was associated with more than four times the odds of extremely preterm delivery. High overall physical workload and shift work also showed moderate evidence of increased risk.
If your job involves heavy lifting, long hours on your feet, or rotating shifts, talk to your employer about modifications. In many countries, workplace accommodations for pregnant employees are legally protected. Even small changes, like sitting for 15 minutes every hour or having someone else handle loads over 10 pounds, can make a difference.
Zinc and Micronutrient Intake
Zinc supplementation has shown a modest but real effect on preterm birth risk. A Cochrane review of 16 trials covering more than 7,600 women found a 14% reduction in preterm birth among women taking zinc compared to placebo. This effect was strongest in women with low incomes, who are more likely to have marginal nutrition to begin with. A standard prenatal vitamin typically contains zinc, but if your diet is limited or you’re concerned about micronutrient gaps, it’s worth checking.
Recognizing Warning Signs Early
Prevention also means catching preterm labor early enough to intervene. The key warning sign is uterine contractions occurring six or more times in one hour, whether or not they’re painful. Other signs include a change in vaginal discharge, pelvic pressure, low back pain that doesn’t go away, and any spotting or fluid leaking from your vagina.
If you notice any of these before 37 weeks, lie down and check for contractions over a full hour. Time them from the start of one to the start of the next. If you count six or more in that hour, or if you have spotting, fluid leakage, or persistent symptoms, contact your provider or go to the hospital. Early detection gives medical teams more options to slow or stop labor and administer treatments that protect the baby’s lungs.