superelaks/Fotolia

Why Are Some Babies Born Premature? Science Is Trying To Find An Explanation

My mother gave birth to both her children prematurely, and after listening to her stories, I remember clinging to my calendar during pregnancy, counting down the weeks until my baby could safely come into the world. Having a baby early is extremely stressful for any parent, emotionally, physically, and financially. Sadly, there's not much families can do to prevent it. So why are some babies are born premature? Researchers are trying to figure it out, but here's what science can — and can't — tell us about foreshortened pregnancies.

In 2016, one in 10 infants were born prematurely, according to data collected by the Centers for Disease Control and Prevention (CDC). Any baby born before 37 weeks is considered premature, but babies born before 32 weeks are at great risk of serious complications, including permanent disability. Premature birth is also a leading cause of infant death, per the CDC. In an email interview with Romper, Dr. Michael Nageotte, a national expert in perinatology and Associate Chief Medical Officer at Miller Children’s & Women’s Hospital Long Beach, explains that most babies born prematurely were either induced because of a medical problem — like preeclampsia or fetal growth restriction — or born spontaneously as a result of uterine inflammation that takes days, weeks, or even longer to develop.

In the case of medically indicated preterm birth, labor is induced to protect the baby, the mother, or both. Spontaneous preterm birth, on the other hand, occurs after sudden, unexpected labor. Science still can't tell us what causes every case. "Spontaneous preterm birth likely is related to issues of uterine capacity or other issues such as in-utero inflammation," writes Nageotte, adding, "We really do not know."

Preterm birth is also dangerous for the baby. According to G. Thomas Ruiz, M.D., OB/GYN, of Orange Coast Medical Center, Fountain Valley, California, "The rule of thumb says for each day we can delay a preterm birth we take up to a week off the NICU stay for the premature infant," he tells Romper. He explains that the single greatest risk factor for preterm birth is having given birth early in the past.

Twins and multiples also put you at greater risk of delivering early, whether through induction or spontaneous labor. Dr. Miao Crystal Yu, OB-GYN, of MemorialCare Saddleback Medical Center in Laguna Hills, California, adds that smoking, drug use, low weight gain during pregnancy, and a history of infections (including urinary tract infections, bacterial vaginosis, and even dental infections) may also contribute to your risk of delivering too soon.

"Most important is to discuss with your doctor if you have a history of preterm labor," Dr. Yu tells Romper in an email interview. "They may suggest starting progesterone medication in the second trimester, or placing a stitch in the cervix to hold the pregnancy longer."

Unfortunately, while great advances have been made in the ability to care for babies born before 37 weeks, obstetrics hasn't made much of a dent in preventing those early births from taking place.

"We have essentially had minimal-to-no impact on the rate of preterm birth in this country or elsewhere other than reducing the frequency of multi-fetal pregnancies resulting from infertility treatments," writes Nageotte.

Troublingly, in 2016, CDC research actually showed a rise in preterm births for the second straight year.

So, if you know you're at risk for preterm birth, what can you do? Besides receiving a stitch in your cervix or intramuscular progesterone injections, not much — although keeping stress in check and avoiding smoking and illegal drugs during pregnancy might reduce your risk.

As for bedrest, medications that control the frequency of contractions, and even intensive prenatal care, none of it is likely to prevent preterm birth, according to Nageotte. "This is frustrating, but remains the state of affairs regarding the modern management of the obstetrical problem of preterm birth," he observes.

Obstetrical science has saved countless lives, and yet, when it comes to babies born prematurely, serious questions remain. If you think you're experiencing symptoms of premature labor, call your doctor right away. Medicine may not be able to explain every case of premature birth, but hospitals can do a lot to care for babies born early.

Check out Romper's new video series, Romper's Doula Diaries:

Watch full episodes of Romper's Doula Diaries on Facebook Watch.