Premature Labor: Causes, Symptoms and Prevention

Premature labor
Image source -

Premature Labor: Causes, Symptoms and Prevention


Did you know? An estimated 15 million babies are born preterm every year across the world. This comes down to more than 1 in 10 babies. Not just that. Preterm birth or premature labor is the predominant reason for infant mortality.


What is premature labor?

A normal pregnancy lasts about 40 weeks. Occasionally, labor begins prematurely, before the 37th week of pregnancy. This happens because uterine contractions cause the cervix to open earlier than normal. Consequently, the baby is born premature and can be at risk for health problems.

Fortunately, research, technology and medicine have helped improve the health of premature babies.


What Might Cause a Preterm Labor?

While no one knows for sure what causes preterm labor, experts point to a number of factors that could play a role in triggering your uterus to begin contracting and your cervix dilating before your baby is ready to come out:

  • Smoking, alcohol and drug use:

    Not only do these behaviors increase your risk of miscarriage, they also increase your baby’s risk of being born early or at a low birth weight (toxins that cross the placenta can keep your baby from getting the necessary oxygen she needs to grow). If there’s ever a reason to quit, pregnancy is it.

  • Short interval between pregnancies:

    Getting pregnant sooner than 18 months after giving birth to your last child increases your risk of preterm birth. And the longer you can wait, the less you’re at risk: A large recent study found that 20 percent of women who wait less than a year between pregnancies give birth before 37 weeks; the rate drops to 10 percent among women who wait a year to 18 months and is less than 8 percent in those who wait more than 18 months to conceive again.

  • Uterine and vaginal infections:

    Infections — both those in the genital tract, such as bacterial vaginosis (BV) and sexually transmitted diseases (STDs) like trichomoniasis, along with infections in the uterus and amniotic fluid — are thought to be responsible for nearly half of all preterm births. Experts suspect they cause inflammation, which in turn leads to the release of prostaglandins — the same substance that initiates labor when you’re full-term. Untreated urinary-tract infections can have the same effect.

  • Pregnancy complications:

    Complications (such as gestational diabetes, preeclamsiaand excessive amniotic fluid) as well as problems with the placenta (such as placenta previa or placental abruption) can make an early delivery more likely.

  • Structural anomalies of the uterus and/or cervix:

    A uterus that is malformed, extremely large or has other structural abnormalities can make it more difficult to carry a baby to term, as can problems with the cervix (such as having a short cervical length or an incompetent cervix — when the cervix doesn’t stay closed the way it’s supposed to during pregnancy).

  • Gum infections:

    Pregnancy hormones make expectant moms more susceptible to periodontal disease, which in turn has been linked to preterm labor. Some experts suspect that the bacteria that cause inflammation in the gums can actually get into mom’s bloodstream, reach the fetus and initiate early delivery. Other research proposes another possibility: The bacteria that cause inflammation in the gums can also trigger the immune system to produce inflammation in the cervix and uterus, triggering early labor.

  • Stress levels:

    Researchers theorize that severe emotional stress — not the kind caused by those raging hormones or a bad day, but the kind that’s related to a traumatic experience — can lead to the release of hormones that in turn trigger labor contractions.

  • Occupational factors:

    Extreme physical stress on the job has also been linked to preterm labor. Researchers have found that women who stand for long periods of time (more than five hours a day) or who have jobs that are extremely physically exhausting are more likely to deliver early.

  • Carrying multiples:

    Multiples are more likely than singletons to arrive early. (Note that infertility treatments make moms more likely to conceive multiples.)

  • Maternal age:

    Women younger than 17 and older than 35 are more likely than their younger counterparts to deliver prematurely. That’s one of the reasons doctors consider (even otherwise healthy) older expecting women to have a “high-risk” pregnancy.

  • A previous preterm birth:

    If you’ve given birth early previously, you’re at an increased risk of having a subsequent preterm birth.

  • If you were preterm yourself:

    A large 2015 study found that women who were born prematurely themselves are at a higher risk of giving birth prematurely (though those odds are still low, at 14.2 percent or less depending on how early you were born).

Most important to remember, however, is that having one of these risk factors doesn’t mean that you’ll necessarily go into preterm labor. Similarly, not having any of the risk factors doesn’t mean that you won’t (some women do for other reasons — or for no known reason at all).


How to recognize Preterm Labor?

A full 80 percent of women who have symptoms of preterm labor will not deliver early. And while it’s likely you’ll never have to put this knowledge to use, it’s good to have in your back pocket: The earlier you recognize that you’re in labor, the earlier you’ll be able to seek treatment. Call your practitioner right away if you are experiencing these labor signs:

  • Regular contractions: That is, those that come every 10 minutes (or more often) and do not subside when you change position (try lying down on your side). These are not to be confused with Braxton Hicks contractions that you’ve possibly already begun to feel, which are practice contractions that are no cause for concern (they’re irregular, don’t intensify and subside when you change position). If you’re not sure, call your practitioner anyway.
  • Change in vaginal discharge: Look for blood-streaked discharge or vaginal bleeding.
  • Fluid leaking from your vagina: It could be a sign your water’s broken. Take a sniff test: If it smells like ammonia, it’s urine. If it doesn’t, it could be amniotic fluid.
  • Period-like cramps: Strong cramps you feel in your lower abdomen or lower back could be a sign of labor.
  • Back pain: A constant low, dull back pain may be a sign of labor.
  • Increased pelvic pressure: If you feel a significant increase in pressure in your pelvic area, call your doctor.

Keep in mind that you can have some or all of these symptoms and not be in labor (most pregnant women experience pelvic pain/pressure or lower back pain at some point). But only your practitioner can tell for sure, so pick up the phone and call. After all, better safe than sorry.



You might not be able to prevent preterm labor — but there’s much you can do to promote a healthy, full-term pregnancy. For example:

  • Seek regular prenatal care.Prenatal visits can help your health care provider monitor your health and your baby’s health. Mention any signs or symptoms that concern you. If you have a history of preterm labor or develop signs or symptoms of preterm labor, you might need to see your health care provider more often during pregnancy.
  • Eat a healthy diet.Some research suggests that a diet high in polyunsaturated fats (PUFAs) is associated with a lower risk of premature birth. PUFAs are found in nuts, seeds, fish and seed oils.
  • Avoid risky substances.If you smoke, quit. Ask your health care provider about a smoking cessation program. Illicit drugs are off-limits, too.
  • Consider pregnancy spacing.Some research suggests a link between pregnancies spaced less than six months apart and an increased risk of premature birth. Consider talking to your health care provider about pregnancy spacing.
  • Be cautious when using assisted reproductive technology (ART).If you’re planning to use ART to get pregnant, consider how many embryos will be implanted. Multiple pregnancies carry a higher risk of preterm labor.


If you have a history of preterm labor or premature birth, you’re at risk of a subsequent preterm labor. Work with your health care provider to manage any risk factors and respond to early warning signs and symptoms.


Also read: What is Labor Induction and How is it done?