7 Warning Signs of Preterm Labor Every Pregnant Woman Should Know

Preterm labor occurs when regular contractions begin to open the cervix before 37 weeks of pregnancy. Recognizing the signs early can make a significant difference in outcomes for both mother and baby. Approximately 10% of pregnancies experience preterm labor, making it crucial for expectant mothers to understand what symptoms to watch for. Early detection allows healthcare providers to intervene and potentially delay delivery, giving the baby more time to develop in the womb.

While not all episodes of preterm labor lead to premature birth, understanding these warning signs empowers pregnant women to seek medical attention promptly. Time is often critical in managing preterm labor, and quick action can help preserve the pregnancy longer.

1. Regular or Frequent Contractions

One of the most common signs of preterm labor is experiencing regular contractions before your due date. These contractions may feel like a tightening sensation in your abdomen, similar to menstrual cramps but typically more intense.

What distinguishes preterm labor contractions from normal Braxton Hicks contractions is their pattern and persistence:

• They occur at regular intervals (every 10 minutes or more frequently)
• They become progressively stronger over time
• They don’t go away when you change positions or rest
• They may be accompanied by lower back pain that radiates to the abdomen

If you experience more than four contractions in an hour, or eight contractions in two hours, contact your healthcare provider immediately. Timing these contractions from the beginning of one to the beginning of the next can help your doctor assess whether you’re in preterm labor.

2. Lower Back Pain or Pressure

Persistent lower back pain is a significant indicator of preterm labor, especially if it’s different from your normal pregnancy discomfort. This pain typically presents as a dull ache in the lower back that may come and go rhythmically or remain constant.

The backache associated with preterm labor has distinct characteristics:

• It doesn’t improve with rest or position changes
• It may feel like waves of pressure moving around to the abdomen
• The pain may intensify and then decrease in a regular pattern
• It’s often accompanied by a feeling of heaviness in the pelvis

Many women describe this sensation as similar to menstrual cramping that radiates from the back around to the front. Unlike typical pregnancy back pain that improves with rest or massage, labor-related back pain persists and often worsens over time.

3. Pelvic Pressure or Cramping

A feeling of pressure in the pelvis or lower abdomen is another telltale sign of preterm labor. This sensation may feel like the baby is pushing down, creating pressure on your pelvic floor and making you feel like you need to have a bowel movement.

This pelvic pressure occurs because the baby’s head is descending and pressing against the cervix as it begins to dilate. Women often describe this symptom as:

• A heavy feeling in the pelvis or vaginal area
• Cramping similar to menstrual cramps in the lower abdomen
• Thigh pressure or achiness
• An increased urge to urinate due to pressure on the bladder

This pressure is particularly concerning when it occurs before 37 weeks and is accompanied by other symptoms like contractions or back pain. The intensity may increase over time as labor progresses.

4. Changes in Vaginal Discharge

Any significant change in vaginal discharge during pregnancy warrants attention, especially when it might signal preterm labor. The cervix produces a mucus plug during pregnancy that helps protect the baby from infections, and losing this plug can indicate that the cervix is beginning to dilate.

Watch for these specific changes in vaginal discharge:

• An increase in the amount of discharge
• A change from thick to watery or mucus-like consistency
• Bloody or pink-tinged discharge (often called “bloody show”)
• Discharge containing thick mucus, possibly with streaks of blood

While some increase in discharge is normal during pregnancy, a sudden change—especially if the discharge is watery, mucus-like, or contains blood—should be evaluated immediately. This could indicate that your cervix is changing and labor may be beginning.

5. Fluid Leaking from the Vagina

Leaking fluid from the vagina could indicate that your water has broken (rupture of membranes), which is a serious sign of preterm labor when it occurs before 37 weeks. This differs from normal discharge or urine leakage, which are common in pregnancy.

Amniotic fluid has distinct characteristics that help identify it:

• It’s usually clear or pale yellow in color
• It has a slightly sweet smell, unlike urine which has an ammonia odor
• The leaking continues rather than stopping after a small amount
• You have little to no control over the leaking

If you’re unsure whether you’re leaking amniotic fluid or experiencing normal pregnancy discharge, it’s always better to err on the side of caution and contact your healthcare provider. A ruptured membrane significantly increases the risk of infection and usually necessitates delivery, regardless of gestational age.

6. Abdominal Cramping with or without Diarrhea

Cramping in the lower abdomen that feels similar to menstrual cramps or gas pains can be an early warning sign of preterm labor. These cramps may occur with or without diarrhea and can sometimes be mistaken for digestive issues.

The cramping associated with preterm labor typically has these features:

• Rhythmic or wave-like pattern that comes and goes
• Located low in the abdomen, below the belly button
• May be accompanied by intestinal cramping or loose stools
• Doesn’t resolve with hydration or rest

Some women experience diarrhea or frequent bowel movements as their body prepares for labor. The hormone prostaglandin, which helps soften the cervix, can also affect the digestive system. While occasional cramping or diarrhea alone isn’t necessarily cause for alarm, when combined with other symptoms of preterm labor, it requires medical evaluation.

7. Flu-like Symptoms

Feeling generally unwell with flu-like symptoms—including nausea, vomiting, or diarrhea—can sometimes accompany preterm labor. While these symptoms might seem unrelated to labor, they can indicate that your body is preparing for delivery.

Pay attention if you experience:

• Sudden onset of nausea or vomiting, especially if you’ve been feeling well
• A general feeling of being unwell or “off”
• Low-grade fever (though actual fever may indicate infection)
• These symptoms combined with any other signs of preterm labor

While it’s entirely possible to have actual flu or a stomach bug during pregnancy, these symptoms shouldn’t be dismissed, especially if they occur alongside contractions, back pain, or other labor signs. Your body releases hormones during early labor that can cause these flu-like feelings, so it’s important to monitor all symptoms together rather than in isolation.

Main Causes of Preterm Labor

Understanding what causes preterm labor can help identify women at higher risk, though in many cases, the exact cause remains unknown. Multiple factors can contribute to early labor:

Previous Preterm Birth

Women who have previously delivered a baby prematurely have a significantly higher risk of preterm labor in subsequent pregnancies. The risk increases with each previous preterm delivery.

Multiple Pregnancy

Carrying twins, triplets, or more multiples stretches the uterus and increases the likelihood of preterm labor. Approximately 60% of twins and over 90% of triplets are born prematurely.

Uterine or Cervical Abnormalities

Structural issues with the uterus or an incompetent cervix (one that begins to open too early without contractions) can lead to preterm labor. Cervical insufficiency often develops in the second trimester and may not present with typical labor symptoms.

Infections

Certain infections, particularly those of the urinary tract, vagina, or amniotic fluid, can trigger preterm labor. Bacterial vaginosis and urinary tract infections are among the most common infectious causes.

Chronic Health Conditions

Pre-existing conditions such as high blood pressure, diabetes, kidney disease, or thyroid problems increase the risk of preterm labor. Proper management of these conditions throughout pregnancy is essential.

Lifestyle Factors

Smoking, alcohol use, drug abuse, inadequate prenatal care, high stress levels, and poor nutrition all contribute to increased preterm labor risk. Physical abuse or domestic violence also significantly elevates the risk.

Pregnancy Complications

Problems during pregnancy such as placenta previa, placental abruption, too much or too little amniotic fluid, or preeclampsia can lead to preterm labor or necessitate early delivery.

Short Interval Between Pregnancies

Becoming pregnant again less than 6-18 months after giving birth increases the risk of preterm labor, as the body may not have fully recovered from the previous pregnancy.

Prevention Strategies

While not all cases of preterm labor can be prevented, there are several evidence-based strategies that can reduce your risk:

Regular Prenatal Care

Attending all scheduled prenatal appointments allows your healthcare provider to monitor your pregnancy closely and identify potential problems early. Early detection of risk factors enables timely intervention.

Maintain a Healthy Lifestyle

A balanced diet rich in nutrients, adequate hydration, and appropriate weight gain support a healthy pregnancy. Avoid smoking, alcohol, and recreational drugs, all of which significantly increase preterm labor risk.

Manage Chronic Conditions

If you have pre-existing health conditions like diabetes or high blood pressure, work closely with your healthcare team to keep them well-controlled throughout pregnancy. Uncontrolled chronic conditions dramatically increase the risk of pregnancy complications.

Treat Infections Promptly

Report any signs of infection to your healthcare provider immediately. Urinary tract infections, vaginal infections, and other bacterial infections should be treated promptly to reduce preterm labor risk.

Reduce Stress

High stress levels have been linked to preterm labor. Practice stress-reduction techniques such as prenatal yoga, meditation, adequate rest, and seeking support from family, friends, or a counselor when needed.

Progesterone Supplementation

For women with a history of preterm birth or a short cervix, your doctor may recommend progesterone supplementation during pregnancy. This hormone can help prevent early labor in high-risk women, but should only be used under medical supervision.

Cervical Cerclage

Women with cervical insufficiency may benefit from a cervical cerclage—a stitch placed around the cervix to help keep it closed during pregnancy. This procedure is typically performed between 12-14 weeks of pregnancy in high-risk women.

Limit Physical Strain

While moderate exercise is generally safe during pregnancy, avoid heavy lifting, prolonged standing, and excessive physical exertion, especially if you’re at high risk for preterm labor.

Frequently Asked Questions

When should I call my doctor about potential preterm labor symptoms?

Call your healthcare provider immediately if you experience any signs of preterm labor before 37 weeks, including regular contractions, persistent back pain, pelvic pressure, changes in vaginal discharge, or fluid leaking. Don’t wait to see if symptoms resolve on their own—early intervention can make a significant difference.

Can Braxton Hicks contractions be mistaken for preterm labor?

Yes, Braxton Hicks contractions are often confused with preterm labor. However, true labor contractions are regular, increase in intensity, don’t go away with rest or position changes, and occur at increasingly shorter intervals. Braxton Hicks contractions are irregular, usually painless, and stop when you rest or change position. If you’re unsure, always contact your healthcare provider.

How is preterm labor diagnosed?

Your healthcare provider will perform a physical examination, including checking your cervix for dilation and effacement. They may use ultrasound to assess cervical length and fetal position, and perform a fetal fibronectin test, which can help predict whether you’re likely to deliver soon. Monitoring uterine contractions and fetal heart rate also helps confirm preterm labor.

Can preterm labor be stopped?

In some cases, preterm labor can be stopped or delayed, especially if caught early and if your water hasn’t broken. Your doctor may recommend bed rest, hydration, and close monitoring. However, medical interventions should only be undertaken under professional supervision, and the decision depends on various factors including how far along you are and the condition of both mother and baby.

What is the difference between preterm labor and premature birth?

Preterm labor refers to the onset of labor before 37 weeks of pregnancy, while premature birth means the baby is actually born before 37 weeks. Not all women who experience preterm labor will have a premature birth—in many cases, labor can be stopped or delayed, allowing the pregnancy to continue.

Am I at risk for preterm labor if I’m having twins?

Yes, multiple pregnancies significantly increase the risk of preterm labor. About 60% of twins are born before 37 weeks. The stretching of the uterus and increased hormonal activity with multiple babies make preterm labor more likely. Women carrying multiples should be monitored more closely throughout pregnancy.

Does bed rest help prevent preterm labor?

The evidence on bed rest for preventing preterm labor is mixed. While it was commonly prescribed in the past, recent studies suggest that strict bed rest may not be effective and can even have negative effects. However, your healthcare provider may recommend modified activity or rest based on your individual situation. Always follow your doctor’s specific recommendations for your case.

Can stress cause preterm labor?

High levels of stress have been associated with an increased risk of preterm labor, though stress alone doesn’t directly cause it. Chronic stress can affect hormone levels and immune function, potentially contributing to early labor. Managing stress through relaxation techniques, adequate support, and lifestyle modifications is important for a healthy pregnancy.

References:

• Mayo Clinic – Preterm Labor
• American College of Obstetricians and Gynecologists – Preterm Labor and Birth
• March of Dimes – Preterm Labor and Premature Baby
• NHS – Premature Labour and Birth
• National Institute of Child Health and Human Development – Preterm Labor and Birth