Preterm labor is labor with regular contractions that open your cervix before week 37 of pregnancy—in other words, before your baby is considered full-term. The most common early sign is frequent, regular tightening of your belly every 10 minutes or more often, though not all contractions are painful and some preterm labor feels surprisingly mild. Most readers find this page because something feels different, and you need to know now whether to call your provider or go to the hospital.
This guide covers the warning signs doctors watch for, what each one means, and what you should actually do about them. The key fact is this: no single feeling proves preterm labor on its own. Only your provider can confirm it with an exam. But you should know what sensations warrant a phone call or a trip in, because early warning signs exist and deserve attention.
Table of Contents
- What Is Preterm Labor and When Does It Start?
- Regular Contractions—The Most Important Warning Sign
- Pelvic Pressure and Back Pain
- Abdominal Cramps, Vaginal Discharge Changes, and Bleeding
- Fluid Leakage and Ruptured Membranes
- When Preterm Labor Feels Subtle or Painless
- Threatened Preterm Labor Versus Active Labor—What Your Provider Checks
- What to Do Immediately if You Suspect Preterm Labor
- Which Pregnancies Carry Higher Risk
- Questions to Ask Your Provider at Your Next Visit
- Frequently Asked Questions
What Is Preterm Labor and When Does It Start?
Preterm labor is labor that begins with regular contractions causing cervical opening after week 20 and before week 37 of pregnancy. Delivery at or after 37 weeks is considered full-term by obstetric standards. The distinction matters because a baby born at 36 weeks faces different medical needs than one born at 34 weeks or 28 weeks, and your provider's response depends on how far along you are when symptoms start.
The second and third trimesters are the window for preterm labor risk. In the second trimester (weeks 13–27), preterm labor is less common but serious when it occurs. By the third trimester (weeks 28–36), as your body naturally prepares for labor, distinguishing between normal preparation and actual preterm labor becomes harder—which is why knowing the specific signs matters.
Week 20 is the clinical starting point because before then, early loss is called miscarriage rather than preterm labor, and different medical protocols apply. After week 37, labor is no longer considered preterm even if it begins spontaneously. This definition helps doctors communicate clearly and apply the right treatment, and it also tells you when to take warning signs seriously: if you are before week 20 and suspect labor, contact your provider immediately but understand the terminology may differ.
Not all early contractions mean preterm labor is starting. Braxton-Hicks contractions, also called "false labor," are the uterus practicing and tightening irregularly. They feel like a tightening and then release, often painless, and they do not grow closer together or stronger over time. Learning to spot the difference between practice contractions and real labor contractions is one of the most practical things you can do in the weeks before your due date.
Your provider can estimate your gestational age from ultrasound, menstrual dates, or physical exam. This timing determines which interventions are available if preterm labor does begin. At 24 weeks, treatments focus on stopping labor and giving steroids to help the baby's lungs develop. At 35 weeks, doctors may take a different approach. Knowing your exact week helps you understand what your provider is doing and why.
Regular Contractions—The Most Important Warning Sign
The most common early sign is regular or frequent uterine contractions that tighten the belly, which may occur every 10 minutes or more often; contractions may or may not be painful. A contraction feels like a tightening sensation that starts somewhere in your abdomen, spreads, and then releases.
The key word is "regular"—they happen in a pattern with predictable spacing, not randomly scattered throughout the day. In preterm labor, contractions typically occur at least once every 10 minutes. They build in frequency or intensity, or both, over time. Some feel like a tight ball in your lower belly.
Others feel like a dull ache across your whole abdomen or a sharp sensation in one spot. The sensation can radiate to your back, sides, or even into your thighs. You might feel your belly go hard and then soft again as each one passes. The tricky part is that Braxton-Hicks contractions and preterm labor contractions can feel nearly identical.
The difference is consistency and progression. Braxton-Hicks are usually scattered, with no clear pattern of getting closer or stronger. True preterm labor contractions follow a rhythm: they come regularly, they keep coming, and over an hour or two they may grow more intense or closer together. If you have five or more contractions in one hour before week 37, that warrants a call to your provider.
Many women are told that contractions need to be "painful" to count as labor, but research shows nearly 30% of preterm labor cases present without uterine contractions and only half reported pain. You might feel pressure instead of pain, or the sensation might feel so mild you second-guess whether it is real. Do not wait for severe pain.
Regular tightening that repeats every 10 minutes is enough to warrant calling your provider. The right move is to call your healthcare provider or labor line and describe what you feel: how often contractions are coming, what they feel like, how long each one lasts, and how many you have had in the past hour.
Many providers have a nurse line you can reach 24/7. They will ask follow-up questions to help decide whether you need to come in for an exam. It is far better to call and have the nurse reassure you than to wait and wonder all night.
Pelvic Pressure and Back Pain
A persistent dull low-back ache combined with a feeling that the baby is pushing down into the pelvis are warning signs; this sensation differs from normal pregnancy weight and requires provider assessment. Most pregnant people feel low-back pain at some point—your center of gravity shifts, your ligaments loosen, and the weight of your baby pulls on your lower spine.
Preterm labor pain in this area is different: it is persistent, it often comes in a rhythm that matches contractions, and it feels like pressure or heaviness rather than the ache of carrying extra weight. The sensation of the baby "dropping" or pushing down into your pelvis is a specific warning sign. You might describe it as bearing-down pressure, as if the baby is being pushed downward by force.
Some women say it feels like the baby is sitting on a nerve or pushing on a tender spot inside. This pressure may come and go with contractions or may feel constant. If the sensation is new, worsening, or paired with contractions, contact your provider. Lower-back pain that comes with contractions is more concerning than back pain alone.
If your back pain follows a pattern—it tightens, intensifies for 30 seconds or a minute, and then eases—and this pattern repeats every few minutes, that is a strong clue that your uterus is contracting. Back pain that is constant and does not cycle on and off is less likely to be labor, though it should still be mentioned to your provider at your next visit.
Distinguishing normal late-pregnancy back pain from preterm labor pain is one reason to track what you feel over time. Keep a simple written note of when the sensation starts, what it feels like, how long it lasts, how often it repeats, and whether it changes with movement, position, or rest.
If you lie down and the sensation stops, it is less likely to be labor. If you change positions and nothing helps, or if the sensation continues or worsens, call your provider. Some back pain in late pregnancy eases with rest, a heating pad, or a change of position. Preterm labor pain typically does not ease fully with these measures.
A hot shower or bath might make Braxton-Hicks contractions fade within 20 minutes, but true preterm labor contractions will continue. If you rest, hydrate, and relax for an hour and the pattern persists, err on the side of calling your provider rather than waiting.
Abdominal Cramps, Vaginal Discharge Changes, and Bleeding
Mild belly cramps, with or without diarrhea, are listed warning signs; cramping differs from the stretching sensations normal in late pregnancy and warrants contact with your provider. Cramping in preterm labor often feels sharper and more rhythmic than the round ligament pain many pregnant people experience. Round ligament pain is usually one-sided, comes with movement, and fades when you rest.
Preterm labor cramping comes regularly, may affect your whole lower belly, and does not go away with rest or position changes. Diarrhea can accompany preterm labor or can be a sign on its own. Your body may experience cramping and loose stools as your hormones shift in preparation for labor. If you have diarrhea along with regular contractions or pelvic pressure, mention both to your provider.
If you have cramping and diarrhea but no contractions or other warning signs, it is more likely a stomach bug, but call your provider if the cramping continues or worsens or if you develop additional symptoms. A change in vaginal discharge—becoming watery, bloody, or mucus-filled—or an increase in discharge volume before 37 weeks is a warning sign; any vaginal bleeding before term also requires immediate medical evaluation.
Normal pregnancy discharge is milky, without odor, and increases as you get closer to term. A sudden change—to watery discharge, thick mucus, or bloody streaks—deserves attention. Some discharge changes are harmless, but your provider needs to assess them. Vaginal bleeding before 37 weeks is always a reason to contact your provider. This includes light spotting, streaks of blood in discharge, or heavier bleeding.
Some causes are minor (a cervical polyp irritated during intercourse, for example), but bleeding can also signal placental issues or the onset of labor. Do not assume any amount of bleeding is normal just because you are not in severe pain. Describe what you see, when it started, whether it is ongoing or was one-time, and whether it is paired with other symptoms.
If you lose a mucus plug—a thick, stringy or globular mass of discharge sometimes tinged with blood—labor may be starting. The mucus plug seals your cervix during pregnancy. Losing it does not always mean labor is imminent; you can lose it weeks before labor begins. But if you lose it along with contractions, pressure, or bleeding, those symptoms together are worth reporting to your provider immediately.
Fluid Leakage and Ruptured Membranes
Leaking of fluid from the vagina or a sensation of gushing before 37 weeks may indicate rupture of the amniotic sac and requires emergency evaluation; unexplained fluid before term always warrants immediate medical assessment. Amniotic fluid is the clear, odorless fluid surrounding your baby in the uterus. If your membranes rupture—the sac tears—fluid may leak steadily or gush all at once.
This is sometimes called "breaking your water." Leaking amniotic fluid is different from urine or vaginal discharge. Amniotic fluid is clear to slightly yellow, has a faint sweet smell or no smell, and does not feel sticky. If you notice fluid dripping or soaking your underwear or pants and you are not sure whether it is urine, try this test: sit for a while, then stand up quickly.
If you feel a sudden gush of fluid, that is more consistent with ruptured membranes. If it is urine, the sensation usually builds gradually as your bladder fills. Once your membranes rupture, the risk of infection rises steadily over time. Infection can harm both you and your baby. For this reason, a suspected rupture is an emergency and you should head to the hospital or birthing center, not call first to ask permission.
Your provider will check the fluid with a simple test: they place a swab of fluid on a special paper, and if it turns blue or blue-green, that confirms amniotic fluid. Some ruptures are obvious—a gush of clear fluid and the steady drip afterward. Others are slow leaks and harder to notice. You might smell a change in odor, feel damp constantly, or notice your underwear stays wet throughout the day even though you are not urinating more.
If you think you might be leaking fluid before 37 weeks, it is safer to go to the hospital and be checked than to stay home and hope. Occasionally, a small tear in the membrane will seal itself and the leak stops. Your provider will want to monitor you for signs of infection even if the fluid stops leaking.
Do not assume a slow leak has stopped on its own without confirmation from your provider. One visit to the hospital for an evaluation is far less risky than trying to manage a possible rupture at home.
When Preterm Labor Feels Subtle or Painless
Many women are surprised to learn that preterm labor can feel very mild. Some describe their early symptoms as barely noticeable—so subtle they were not sure whether anything was actually happening. Others say they felt pressure rather than pain, or a dull ache they almost missed. This matters because some pregnant people have called their providers saying "I am probably overreacting" or "it is probably nothing," only to learn labor was actually starting.
Nearly 30% of preterm labor cases presented without uterine contractions and only half reported pain. What this means in practical terms is that you do not need to feel severe pain or obvious contractions to warrant a call to your provider. A feeling of pressure, persistent back ache, or a sensation that something feels "off" is enough.
Trust your instinct. You know your body. Some preterm labor presents as persistent pelvic heaviness without sharp pain. Others come as a vague cramp that does not go away with rest or a position change. A few women describe it as feeling like their baby is being pushed downward but without the intense pain they expected labor to involve.
These subtle presentations are real labor, and they deserve the same urgent attention as painful contractions. One reason subtle symptoms are easy to miss is that pregnancy itself is uncomfortable by 30-something weeks. Your back hurts, your hips are sore, you feel pressure from the baby's weight. So when a new sensation appears, it can blend into the background of normal late-pregnancy discomfort.
The question to ask yourself is whether this sensation is new or different from what you have been feeling. Is it more intense? Does it follow a pattern? Is it paired with any other symptoms on this list? If you are in the third trimester and you notice anything on this list that is new or worsening—even if it seems mild—call your provider.
Describe specifically what you feel, when it started, how long it lasts, and how often it repeats. You are not overreacting. Early identification of preterm labor gives you and your medical team the best chance to either stop it or prepare for your baby's arrival safely.
Threatened Preterm Labor Versus Active Labor—What Your Provider Checks
When you arrive at the hospital or clinic with symptoms, your provider will do an exam to figure out exactly what is happening. ACOG (American College of Obstetricians and Gynecologists) distinguishes threatened preterm labor (contractions without confirmed cervical opening) from active preterm labor (contractions with documented cervical change or ruptured membranes); only a provider exam can confirm which is occurring. The difference determines your treatment and what happens next.
Threatened preterm labor means you are having regular contractions, but when your provider examines your cervix, it has not opened (dilated) or changed in a way that signals active labor. Your cervix might be closed, firm, and in its normal position. You might be having four or five contractions an hour that feel very real, but the cervix is not responding.
In this case, your provider may try to stop labor with medications, bed rest, or other interventions. Active preterm labor means your cervix is opening or has already opened (you might be dilated 1 cm, 2 cm, or more), or your membranes have ruptured. Your provider can feel or see the cervical change during an exam.
Active preterm labor is further along than threatened preterm labor and may not be stoppable, depending on how far along you are. Your provider will explain your options. Only a provider exam can confirm which is occurring, so all suspected symptoms warrant immediate contact. This is why you cannot diagnose yourself at home, and why calling or going to the hospital is the right move even if you are not sure whether your symptoms are real.
The exam itself is not painful—your provider uses a speculum or their fingers to look at and feel your cervix and assess whether it is opening, thinning, or changing position. Your provider will also monitor your baby's heartbeat, measure how often contractions are coming, and may do an ultrasound to check the baby's size, position, and the amount of amniotic fluid.
All of this information helps them decide whether labor is truly starting and what your next steps should be. The evaluation usually takes 30 minutes to an hour. You will leave with a clear picture of what is happening and what to do next.
What to Do Immediately if You Suspect Preterm Labor
If you experience warning signs before 37 weeks, here is the action sequence: The goal of going in is twofold: to confirm or rule out preterm labor, and to start treatment if labor is indeed starting. Even if your symptoms turn out to be Braxton-Hicks contractions or a stomach bug, the evaluation is never wasted. It gives you peace of mind and your provider a clear picture of your pregnancy.
- **Call your healthcare provider or the hospital labor line immediately.** Do not wait to see whether symptoms go away. Describe what you are feeling, how long it has been happening, and any other symptoms. Many providers have nurses available 24/7. If you cannot reach your regular provider, call your hospital's labor and delivery unit or go directly to the nearest emergency room.
- **Write down what you are experiencing.** How often are contractions coming? What does the sensation feel like? How long does each one last? How long have you had them? Did anything change in your vaginal discharge? Have you had any bleeding? This information helps your provider assess how urgent the situation is.
- **Go to the hospital or birthing center if you have any of these symptoms: visible vaginal bleeding, sudden gush of fluid, severe belly pain, dizziness, or contractions every 5-10 minutes that do not stop.** Do not drive yourself if the symptoms are severe—call an ambulance or have someone else drive.
- **If symptoms are mild and your provider says you can wait for an appointment, keep monitoring.** Track contractions for the next hour. If they continue or worsen, go to the hospital. If they stop and do not return, call your provider before your next scheduled visit to report what happened.
- **Avoid situations that might trigger more contractions while you wait for evaluation.** Rest, avoid sexual activity, and drink plenty of water. Do not take any over-the-counter medications without checking with your provider first.
Which Pregnancies Carry Higher Risk
Some pregnancies are at higher risk for preterm labor than others. If you have any of these factors, talk with your provider about what warning signs to watch for and when to get evaluated: If any of these apply to you, your provider may already be monitoring you more closely or recommending preventive measures. Do not panic—many people with risk factors carry to term without complications. But knowing your risk profile helps you stay alert to warning signs and take any preventive steps your provider recommends.
- **History of preterm birth in a previous pregnancy.** If you have delivered before 37 weeks before, your risk is higher.
- **Carrying multiples** (twins, triplets, etc.). Multiple pregnancies are more likely to deliver early.
- **Infections, especially urinary tract or sexually transmitted infections** that go untreated.
- **Uterine abnormalities or cervical insufficiency**, conditions your provider would have mentioned in your prenatal care.
- **Vaginal bleeding or placental problems** earlier in this pregnancy.
Questions to Ask Your Provider at Your Next Visit
Understanding your individual risk and what to watch for makes a difference in how confidently you can navigate late pregnancy. Here are concrete questions worth asking:
- **"At what point should I call you or go to the hospital if I think I am in labor?"** Different providers give different guidance. Some want a call at the first sign of regular contractions; others want you to wait until contractions are closer together. Know what your provider wants.
- **"What does a contraction feel like, and how many do I need to have before I should be concerned?"** Your provider can describe what to expect and clarify the difference between Braxton-Hicks and real labor for your specific pregnancy.
- **"Are there any risk factors in my pregnancy that increase my chance of preterm labor?"** If your provider mentions risk factors, ask what signs to watch for and whether there are preventive steps you should take.
- **"If I think my water broke, what should I do?"** Know whether to call first or go straight to the hospital.
- **"Are there any activities, positions, or foods I should avoid in the third trimester?"** Some providers give specific guidance; others do not. Knowing helps you feel confident about your daily choices.
Frequently Asked Questions
How do I know if I'm in preterm labor or just having Braxton-Hicks contractions?
Real preterm labor contractions follow a regular pattern—happening every 10 minutes or closer—and build in frequency or intensity over time. Braxton-Hicks are scattered, with no clear pattern. Track the timing and intensity over an hour. If contractions are coming regularly and do not stop after rest and hydration, call your provider. Mayo Clinic notes contractions may or may not be painful, so do not wait for pain to be severe before calling.
If I notice fluid leaking before 37 weeks, what should I do?
Go to the hospital or call your labor line immediately. Do not wait for an appointment. Leaking amniotic fluid before term requires emergency evaluation because infection risk rises as time passes. Your provider will confirm whether it is amniotic fluid and monitor you for signs of infection.
Can preterm labor happen without pain?
Yes. Nearly 30% of preterm labor cases present without uterine contractions and only half reported pain, so some women experience only pressure, heaviness, or a persistent ache. If you feel anything new or different that matches the warning signs on this page, contact your provider even if it does not hurt.
What is the difference between threatened and active preterm labor?
Threatened preterm labor means you have contractions but your cervix has not opened; active preterm labor means your cervix is opening or your membranes have ruptured. Only your provider's exam can determine which one is happening. Treatment and next steps depend on which type you have.
If my contractions stop on their own, do I still need to go to the hospital?
Call your provider and describe what happened. If contractions truly stop and do not return, your provider may say an exam can wait for your next appointment. But if they return or if you had other symptoms like bleeding or fluid leakage, go to the hospital for evaluation.
What can I do to prevent preterm labor?
Attend all prenatal appointments, follow your provider's guidance on activity level, take prenatal vitamins, manage chronic conditions like diabetes or high blood pressure, avoid smoking and substance use, treat infections promptly, and reduce stress where possible. If your provider has identified risk factors in your pregnancy, ask what additional steps to take.
