How progesterone can decrease odds of preterm birth


Preterm birth (delivering before 37 weeks gestation) can lead to many health complications for newborns. It is estimated that 15 million children each year around the world are born “preemies.”

Additionally, preterm birth is one of the leading causes of infant mortality (death within the first year of life), and babies born prematurely make up a large portion of newborns admitted to the Neonatal Intensive Care Unit (NICU).

For women especially at risk for preterm birth, there are treatments that have proven beneficial at helping women carry to term. Heather Frey, MD, a high-risk obstetrician at Ohio State Wexner Medical Center, says one of the most effective interventions is the administration of progesterone, a naturally occurring hormone. 

Progesterone treatments have decreased preterm births from patients with major risk factors by more than a third.

So, how do you know if you’re at risk for preterm birth? And if so, should you automatically take progesterone? Dr. Frey weighs in: 

What are the risk factors for preterm birth?

“Women who have delivered preterm before are more likely to deliver preterm again. It’s the single biggest risk factor,” says Dr. Frey.

“Smoking, carrying more than one child, doing drugs or getting an infection during pregnancy can put you at a high risk for delivering your baby early,” says Dr. Frey.

There also seems to be a genetic link that can lead to a preterm delivery.

“If your mother or sisters have delivered preterm, you’re more likely to deliver preterm as well,” explains Dr. Frey.

Another risk factor is having a short cervix.

The cervix is the opening to the womb. During birth, the cervix widens and shortens, allowing the baby to pass through to the birth canal. In women who have short cervixes, this process is more likely to begin early.

Wait, how do I know if I have a short cervix?

“At Ohio State, we now offer a procedure called a universal cervical length screening,” explains Dr. Frey. “We use a transvaginal ultrasound to measure the length of the cervix. This is done around 16-24 weeks—the same time we do a regular anatomy ultrasound.”


Who is a good candidate for progesterone hormone treatment?

The two preterm birth risk factors that make someone a candidate for progesterone treatments are having delivered a preterm baby before and having a short cervix.


What do progesterone treatments involve?

Progesterone can be administered two ways: through an injection or a vaginal pill.

“We typically suggest that women with a history of preterm delivery receive progesterone injections, while women with short cervixes take the vaginal pill,” says Dr. Frey.

Treatments usually begin around 16 weeks of pregnancy, after a woman has her first ultrasound, and continue through 36 weeks.


How successful are the treatments?

While their effectiveness varies from woman to woman, progesterone often shows positive results.

“Progesterone treatments can decrease the likelihood of delivering preterm by 45 percent in women with short cervixes and over 30 percent in women who have previously delivered preterm,” shares Dr. Frey.

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