Overview

What Causes Preterm Labor & Birth?

What Causes Preterm Labor & Birth?

Possible causes of preterm birth include the following:

  • maternal or fetal stress
  • infection or inflammation
  • vaginal bleeding that comes from inside your uterus
  • and overdistention of the uterus. Overdistention usually happens to women who’ve had twins or triplets or excess amniotic fluid during labor. 

There are other factors that seem to increase your chances of having a preemie. These include:

  • Short cervix - Your cervix—the opening of your uterus—shortens to prepare for childbirth. If an ultrasound or exam shows that your cervix has shortened too early in your pregnancy, you have a higher chance of delivering a preemie.
  • Pregnancy spacing less than six months - You’ve become pregnant within six months of your last pregnancy.
  • Multiple gestations - You’re carrying more than one baby (twins or triplets).
  • Smoking and substance abuse - You use tobacco, prescription pain medications, or street drugs.
  • Chronic medical conditions - You have a medical problem, such as diabetes or high blood pressure (hypertension).
  • Underweight, overweight, or poor nutrition - Being under or overweight increases your chance of having a preemie.
  • Little or no prenatal care.
  • Problems with you uterus or cervix - If you’ve had surgery on your uterus or cervix, have uterine fibroids, or have a uterine anomaly (such as bicornuate or septate uterus), you may have higher odds of delivering a preemie.

But, keep in mind that although these factors increase your chances of having a preemie, they are only part of the story. Most women who deliver preemies have none of these problems.

Infections During Pregnancy

When a woman has a spontaneous preterm birth at a very early gestational age (between 20 and 32 weeks gestation) the most common reason is infection or inflammation.

In some cases, bacteria or viruses can cause an infection in your uterus, vagina, bladder, or some other part of your body. This can cause preterm birth.

But some preterm deliveries happen when the mother has an abnormal or inflammatory response to normal vaginal or cervical bacteria. Even infection or inflammation in a mom’s gums and teeth (called periodontal disease) can cause preterm birth. 

Unknown Causes of Preterm Birth

In many cases, it’s not possible for doctors to identify the exact cause of preterm birth. But, having a complete history of a woman’s past births may help. This should include information and details about the timing and symptoms a woman had during a previous preterm delivery. 

Closely reviewing a woman’s medical records may also help pinpoint the cause of a past preterm birth.

Will My Baby Have Health Problems If It's Born Too Early?

Having a preemie can be very dangerous. Preterm birth and preterm delivery are the most common causes of neonatal death, or your child dying when he/she is a baby. Preemies can have long-term health problems including:

  • blindness & deafness,
  • behavioral & developmental problems,
  • chronic lung disease,
  • cerebral palsy,
  • bleeding in the brain,
  • and problems with the intestines. 
When you go into labor and whether you have any complications during labor will determine what health problems your preemie may have in the future.

How Does Preterm Labor Affect the Mother?

Preterm births usually happen because of complications from infection or abruption. Abruption is a medical condition where the placenta detaches from (or comes off) your uterine wall too soon.

Infections For the Mother

But these complications can cause health problems for the mother too. Mothers may get a severe infection that requires antibiotic treatment from an IV. Some infections may become life threatening.

Many women need a C-section (Cesarean section) during preterm labor because preemies are often breeched or laying in some other unusual position inside the womb. Preemies can also have a difficult time during labor. Mothers giving birth to preemies may need C-sections so their babies can be more comfortable during labor.

Signs & Symptoms of Preterm Labor

The most common signs that you may give birth to a preemie include regular uterine contractions. Some women describe these symptoms as severe menstrual-type cramps in the lower part of the abdomen (tummy area). 

Some women experience tightening in their abdomen in a band-like fashion that starts in the lower back and travels to the anterior (front) part of lower abdomen. Other symptoms include:

  • pressure in your vagina,
  • changes in vaginal discharge,
  • and vaginal bleeding or losing fluid.

Many women have preterm contractions as early as 23–24 weeks gestation. 

But when these contractions happen regularly (less than every 10 minutes) or if you have more than six contractions per hour, you should see a doctor immediately.

When Should I Contact My Doctor About Contractions?

If you’ve given birth to a preemie before, you should call your provider immediately if you are experiencing any of these symptoms:

  • regular uterine contractions,
  • pelvic pressure,
  • change in your vaginal discharge,
or vaginal bleeding or loss of fluid.

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