Preterm C-section could raise risk of breathing difficulties: Study

By Dr. Ananya Mandal, MDFeb 12 2012

Cesarean sections are often performed when a baby is going to be born early. Labor may also be induced when a woman's water breaks too early in the pregnancy. However, two new studies suggest that these common practices may, in fact, not benefit babies. The two new studies were presented Thursday at the annual meeting of the Society for Maternal-Fetal Medicine.

In the first study researchers at Johns Hopkins and Yale University reviewed 2,560 births in New York City from 1995 to 2003 and found that underweight premature infants had a 30 percent greater chance of developing breathing problems when delivered by C-section compared to those delivered vaginally. The team was led by Dr. Erika Werner, assistant professor of Maternal Fetal Medicine at the Johns Hopkins School of Medicine.

The findings were limited to a small subgroup of babies who grow in the fetus weighing less than 90 percent of babies at the same gestational age — a condition called intrauterine growth restriction. One in 8 babies is born prematurely in the United States, according to the March of Dimes.

“I don’t think we know for sure why this is the case,” Werner said about the results.  “In theory, you can say that it has something to do with contractions and the birthing process, getting the lungs ready for breathing outside the body, but we don’t know for sure.”

Werner said that since her study is only retrospective, the next step is to create a new prospective study. “We need to follow patients in the future starting from when they deliver,” Werner said.  “What matters even more is if there is a difference in these babies at 1 year of life or 5 years of life.  And we need to start to look at what preterm vaginal birth does at the biochemical level compared to cesarean sections.”

“Although in many instances, a C-section is medically necessary for the health of the baby or the mother, this research shows that in some cases the surgery may not be beneficial for some infants,” said Dr. Diane Ashton, deputy medical director of the March of Dimes. Ashton was not involved in the study.

The seemingly rare condition can develop if an expectant mother has severe hypertension or kidney disease, or if a baby is malnourished, according to Dr. Lucky Jain, neonatologist and medical director of the Emory Children’s Center at Emory University. In the study, the babies were delivered before 34 weeks of pregnancy.

Pre-term babies may be at higher risk for stillbirth during vaginal delivery, so they are more often delivered by c-section. While the findings may give physicians pause to consider an alternate delivery method, Jain said the findings are not likely to change practices for most. “The study tells me that it may not be a bad idea to let the mother give birth vaginally,” said Jain, adding that, oftentimes, the decision is made based on an individual mother’s situation. “To change practice, one would have to do a randomized trial, which would be hard to do given the small numbers,” said Jain.

However, Dr. Abdulla Al-Khan, director and section chief of Maternal Fetal Medicine and Surgery at Hackensack University Medical Center, said not to look at this new study as a blanket statement about C-sections. “No one in the medical community is in disagreement that natural birth is the best way to achieve birth,” Al-Khan told FoxNews.com.  “But in modern medicine, we have saved lives in doing C-sections.  If we look just over the last 50 years, neonatal mortality has definitely decreased in this country.”

In regards to babies who are small for their gestational age who are born preterm, Al-Khan said that sometimes C-sections are absolutely necessary to save both the life of the baby and the mother. “Clearly, if we have a baby who is growth-restricted, not every baby needs to be delivered prematurely,” Al-Khan said. “We look at the blood flow in the baby’s umbilical cord and make a better determination if there’s a need for delivery or not.  But if a baby is growth-restricted and has abnormal blood flow, they need to be delivered.  The likelihood of you delivering this baby naturally is very slim, and when you labor these kinds of babies, you’re going to end up with a catastrophe.”

The second study examined induction of labor after the rupture of membranes (meaning the bag of water breaks). When this occurs, labor is often induced to prompt immediate delivery and lower the risk of infection in the baby. However, 536 women with ruptured membranes were assigned to undergo either induction of labor or close monitoring. Close monitoring extended pregnancy on average by 3.5 days.

The study showed that the risk of infection in the newborn was similar - and quite low - in both groups as were rates of respiratory distress in the baby. “Due to these findings, we suggested expectant management as opposed to induced labor when possible,” the authors said in a news release.