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Learn how to prevent and identify preterm labor

Being pregnant for the first time has its ups and downs. On the bright side, you don’t know what you don’t know, so you don’t worry about things you might worry about if, well, you know… you knew.

Alternately, you worry about every little flutter, kick (or lack of kick) and pang. But would you know how to identify preterm labor?

If it’s your first pregnancy, you likely have no idea what preterm labor feels like, and you might not know the best response.

According to the Mayo Clinic Guide to a Healthy Pregnancy, preterm labor is “when contractions begin to open the cervix before the 37th week of pregnancy.”

Don’t you feel better? I mean, we all know what it feels like when our cervix opens, right?

Of course not. That’s why the guide also describes three key signs and symptoms of preterm labor.

What you might experience

  1. Uterine contractions — possibly painless — that feel like a tightening of your abdomen. When I began preterm labor with my second child, my abdomen felt like concrete. I could have bounced a brick off my belly button. There was no question it was contracting; we just didn’t know what that meant.
  2. Contractions accompanied by low back pain or a feeling of heaviness in your lower pelvis and upper thighs. I didn’t have these symptoms at all, yet I was still diagnosed with preterm labor. I’m so glad I called the triage nurse to discuss my symptoms; my second pregnancy really taught me that my OB-GYN’s nursing team never minded a phone call.
  3. Changes in vaginal discharge, such as light spotting or bleeding, watery fluid leaking from your vagina or a thick discharge tinged with blood.

Dr. Myra Wick of the Mayo Clinic in Rochester, Minnesota, is board-certified in both OB-GYN and Medical Genetics. She also co-authored the Mayo Clinic Guide to a Healthy Pregnancy.

 “Our OB nurses review educational materials concerning preterm labor with each of our patients at the time of the anatomy ultrasound, typically between 18 and 20 weeks,” Dr. Wick says.

“This includes precautions and instructions to call our OB triage nurses with signs or symptoms of preterm labor. If the information reported to the nurse is concerning for preterm labor, the patient will be instructed to come to the clinic or Labor and Delivery for evaluation.”

What may cause preterm labor?

According to the March of Dimes, in nearly 40 percent of premature births, the cause is unknown, but studies suggest four main causes of spontaneous premature labor:

  1. Infections/Inflammation
    Studies suggest that premature labor is often triggered by the body’s natural immune response to certain bacterial infections, such as those involving the genital and urinary tracts and fetal membranes. Even infections far away from the reproductive organs, such as periodontal disease, may contribute to premature delivery.
  2. Bleeding
    The uterus may bleed because of problems such as placental abruption (i.e., the placenta peels away, partially or almost completely, from the uterine wall before delivery). Bleeding triggers the release of various proteins involved in blood clotting, which also appear to stimulate uterine contractions.
  3. Stretching
    The uterus may become overstretched by the presence of two or more babies, excessive amounts of amniotic fluid, or uterine or placental abnormalities, leading to the release of chemicals that stimulate uterine contractions.
  4. Maternal or fetal stress
    We all know stress is not our friend. If an expecting mom experiences ongoing stress, or the fetus experiences physical stress (such as insufficient blood flow from the placenta), the fetus may produce a stress-related hormone called corticotrophin-releasing hormone (CRH). CRH may stimulate production of a cascade of other hormones that trigger uterine contractions and premature birth.

Now you feel stressed about stress, right? Breathe!

“Patients frequently ask about work-related stress,“ Dr. Wick says. “We see a lot of pregnant patients in stressful positions: Surgeons, oncologists, nurses lifting heavy patients. The vast majority work right up to delivery without significant complication. Just recently, one of our own residents was working the night shift in Labor and Delivery right up to her due date!“

Survival rates

The earlier in pregnancy a baby is born, the more likely he is to have health problems, reports the March of Dimes. But advances in medical care mean even babies born very premature are more likely to survive today than ever before, according to the March of Dimes.

The March of Dimes reports babies born earlier than 23 weeks have a much smaller chance of survival than babies born after 23 weeks.

“About 9 out of 10 babies born at 28 weeks survive,” March of Dimes reports. “But many have serious health problems… Premature babies have less time to develop in the womb than babies who arrive on time. This puts them at greater risk of medical and developmental problems… Between 23 and 26 weeks, every extra day in the womb increases a baby’s chance of survival by 2 to 4 percent.”

The Mayo Clinic’s Dr. Wick says, “We now define viability at 23 weeks; this is referred to as the limits of viability. Our neonatologists counsel the patient, ideally before delivery, regarding the survival and outcomes if delivery were to occur at a given gestational age.

“Survival rate in the U.S. after delivery at 23 weeks is less than 25 percent. In addition, there is also significant morbidity for infants born near viability including infection, bleeding in the brain, problems with lung development, necrotizing enterocolitis (a gastrointestinal emergency due to inadequate blood flow to the intestine), and long-term cognitive problems,” Dr. Wick adds.

Real stories of preterm labor

“I went into labor at 26 weeks with [my son], and [physicians] were unable to stop my contractions so I delivered him at 2 pounds,” says Joanna. “[It was the] scariest day of my life.” Tristan is healthy now, but the family happened to be visiting out of town when Joanna’s contractions began, so they spent six months in the hospital.

Women who have given birth early once tend to have other early births, as well.

Joanna’s daughter arrived at 33 weeks, weighing five pounds. “Luckily, she was healthy and did 10 days in the NICU, which was a cake walk compared to [our son],” she shares.

In my situation, Charlie arrived at 33 weeks, weighing 4 pounds, 14 ounces, because he had fluid in a lung cavity and needed to be delivered.

His sister, Mary Emma, born 17-1/2 months later at 36 weeks, came a week earlier than preferred after testing well for lung development. She weighed 8 pounds, 12 ounces, and our physicians were concerned her size would get dangerously large (thank you, gestational diabetes).

Preventing preterm labor

”In many cases, we don’t know what causes preterm labor,” says Dr. Wick. “However, there is a ‘laundry list’ of reported risk factors including infection, drug abuse, smoking, multiples (twins, triplets), placental problems, problems with your cervix (cervical shortening), procedures on your cervix prior to pregnancy, history of preterm labor with previous pregnancy, poor nutrition or very low body mass index and inadequate prenatal care.”

Patients with a history of preterm labor may be offered progesterone supplementation to prevent recurrent preterm labor; there is no evidence that progesterone supplementation will prevent preterm labor in women without a previous history, or in women who are carrying twins.

Dr. Wick emphasizes, “The simplest advice is to establish a healthy lifestyle prior to pregnancy, which you continue into your pregnancy!”

What now?

If you do begin preterm labor, relax. Neonatologists help stabilize babies born prematurely every day. In fact, Dr. Wick reports that approximately 12 percent of infants in the United States are born prematurely, with almost 2 percent delivered before 32 weeks.

If you receive your care at a hospital without a NICU, your baby may be transferred to a hospital with a NICU where neonatologists will provide special care for your preterm baby.

Dr. Wick says, “The most important factors in preventing preterm birth include avoidance or discontinuation of unhealthy lifestyle practices associated with preterm labor (e.g., smoking, illegal drug use), and establishing good prenatal care.


As with any health concerns during pregnancy, signs or symptoms of preterm labor should be reported to your health care provider immediately.

Read more about prematurity

Think your baby won’t come early? Think twice and prepare!
Benefits of kangaroo care for preemies
Advice for navigating the NICU

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