Discussing the risk of premature birth

Prematurity, defined as birth before 37 weeks, is the leading cause of death and disabilities in babies today.

It’s a pregnancy risk that should never be taken lightly, cautioned maternal-fetal medicine specialist Dr. Alexander Saucedo, assistant professor of obstetrics and gynecology at Baylor College of Medicine.

“One of the biggest things I try to convey to patients is just how real the risk is and how important it is that we screen and attempt to reduce that risk so we don’t have to deliver early. It’s not just the premature birth that presents risk, it’s the complications we see in these babies that will impact their health for the rest of their lives, if they survive,” Saucedo said. “It’s one of the most important conversations I have with patients.”

The biggest known risk factor

The first step in preventing early delivery is assessing each patient’s baseline risk.

“If the patient has had prior preterm births due to chronic hypertension, diabetes or preeclampsia, for example, we try to identify and modify those risk factors from the onset in this pregnancy, whether it’s starting them on low-dose aspirin therapy to reduce the risk of preeclampsia and fetal growth restriction or controlling their diabetes from an early gestational age,” he explained.

“Having a history of preterm birth is the biggest known risk factor for prematurity,” Saucedo said. “Not only does preterm birth tend to recur, it often recurs in a more severe form in the next pregnancy.”

Other risk factors for preterm birth include being underweight or overweight, short intervals between pregnancies, racial and socioeconomic differences, infections, smoking and other modifiable lifestyle behaviors.

Surgical and nonsurgical interventions

“For patients with a history of prematurity, we offer transvaginal cervical length screening, an ultrasound procedure to assess how short their cervix might be in this pregnancy – a well-known risk factor for prematurity,” Saucedo said. “If the screening shows the cervix is shortened, then we consider surgical or medical interventions to reduce their risk of preterm birth.”

Surgical intervention, known as a cerclage, involves stitches placed around the cervix to keep it closed during pregnancy. It is typically performed between 16 and 24 weeks.

Nonsurgical options include medications such as vaginal progesterone that have also been shown to reduce the risk of preterm birth.

Recent studies provide new hope

“Prematurity is one of the most heavily researched areas in obstetrics because it’s so multifaceted and poorly understood,” Saucedo noted. “There are many factors that can initiate that labor process or lead to premature rupture of membranes.”

There may be light at the end of the tunnel, thanks to the volume of research underway.  A large clinical trial recently found that using a combination or “bundle” of interventions for patients at high risk of prematurity, including daily vaginal progesterone, low-dose aspirin and weekly nursing calls, improved neonatal outcomes.

“Another big trial underway involves twin pregnancies, which are known for their risk for preterm birth,” he continued.

A previous study found that cerclage performed when the patient starts to dilate prematurely – known as rescue-indicated cerclage or physical examination-indicated cerclage – significantly decreased preterm birth and perinatal mortality. Today’s larger study aims to determine if ultrasound-indicated cerclage in twin pregnancies where the patient has a short cervix identified before 24 weeks reduces the risk of preterm birth.

Optimizing outcomes for preterm babies

“Neonatologists do wonders today in terms of the survival rate and resuscitation of premature babies,” Saucedo said.

“Thirty or 40 years ago, the mortality rate of a baby born before 25 to 28 weeks was about 50%. Today they have an 80% to 100% survival rate. We work hand in hand with our neonatologists here, and other pediatric specialists as needed, to optimize outcomes for these preterm babies.”

“We also work closely with the adult specialists needed to optimize the mother’s health so she can remain pregnant as long as possible, avoiding early delivery,” he added.

Saucedo recommends women at risk of premature birth carefully consider the best hospital for delivery. “If we anticipate a baby is going to deliver before 32 weeks, we recommend a center with a NICU of level three or higher to ensure the specialized care these newborns require.”

By Sharon Dearman, writer in the Department of Obstetrics and Gynecology