March 5, 2004

Combating premature births

By Steve Zimmerman
Ashland Daily Tidings

Before you can begin to understand why premature births occur, you need to understand what constitutes a normal term pregnancy.

	Oregon Health Sciences University student Jenny Kimsey assesses three-day-old Joshua Ruthstrom under the watch of instructor Ute Sherbow. Denise Baratta | Ashland Daily Tidings

"From the start of the first day of a woman's last menstrual period to her due date is 40 weeks," Doctor Brian Sohl, a maternal fetal medicine specialist at Rogue Valley Medical Center, explained. "From conception to due date is 38 weeks. Anything pre-term is considered to be any birth under 37 weeks."

When Sohl was a resident from 1984 to 1988, babies born under 28 weeks had a very low chance of survival. That has changed substantially in the past 15 years.

"The advances for survival of pre-term babies have been advances in the nursery by the neonatologists and their team and not by the obstetricians," he said. "In fact, I think we (obstetricians) have not done very well, as evidenced by the fact that pre-term labor is increasing."

Sohl said putting a finger on the cause of premature birth is difficult but a couple of factors could explain the rise.

"The demographics of who is having babies is changing," he noted. "We are seeing more women at the extremes of their reproductive years, in particular older women having their first children in their late 30s and early 40s, that are at an increased risk."

Obviously, making regular visits to the doctor and getting proper prenatal care, including nutritional advice, is very important in the birth process

One other aspect that could be causing an increase in premature birth noted by Sohl is the increase in twin and triplet pregnancies. In 1990, nationwide there were 94,000 twin pregnancies and in the year 2000, there were 119,000, a 27 percent increase in 10 years. Triplet births have gone up 139 percent in 10 years. This rise is due to advances in reproductive assisted technology, namely fertility pills or in vitro fertilization.

"In singleton babies, 10.4 percent deliver pre-term and 1.6 percent deliver before 32 weeks," Sohl said. "But with twins, 57.4 percent deliver pre-term and 11.8 percent before 32 weeks. In triplet births, 92.5 deliver pre-term and 36.7 percent before 32 weeks."

People who have more physically demanding jobs and very stressful jobs have an increased risk of delivering early. But those living in lower socioeconomic groups also have an increased risk.

"We don't know exactly what that causes that," Sohl said. "Is it stress in that environment, from making enough money to pay the rent or having two or three jobs to make ends meet, or is it the fact they tend to smoke more or use illegal drugs and alcohol? It is hard to find statistics that will say any one of those things is a risk factor but probably a combination of those factors are."

A misperception is that premature birth runs in the family, according to Sohl.

"That has some small association," he said. "But clearly, a woman's prior reproductive history does play a role. If a woman has delivered one term baby before, she has a 4.4 percent chance of a pre-term delivery. If she had one pre-term baby delivered previously, she has a 17 percent chance and if she has had two pre-term deliveries, she has a 28 percent chance of another pre-term delivery."

Sohl said he would not counsel someone to not have a baby if they have delivered pre-term previously. He said that is too big a decision for him to make.

"But I would make them aware of the risk," he said. "And I would try to make them aware that we do not have a good way of predicting if they will deliver pre-term and a good way of treating pre-term labor."

Sohl said there are a variety of very uncomfortable drugs that can be used to stop pre-term labor. But he added that none of them have been shown to do more than delay delivery for a couple of days.

"We can slow down labor enough to allow a mother, from say Klamath Falls, to come down the mountain and deliver at Rogue Valley in the NICU," he explained. "And we can usually slow down labor long enough to administer a drug called Betamethasone, which is a drug that helps prepare the baby's brain and lungs for a pre-term delivery."

Sohl said as little as four weeks can make the difference between life or death, or the quality of life, for a premature infant. And, in general, pre-term babies are breach babies or have difficulty making it through labor and are taken by caesarean section.

"A baby born at 25 weeks has a 50 percent chance of living and has, if it survives, a 50 percent chance of brain injury," he said. "Just four weeks later, at 29 weeks, the baby has well over a 90 percent chance of living and living a normal childhood. Between 24 and 28 weeks, there is a very steep survival curve where every single day the mom doesn't deliver adds a couple of percentage points to the survival chance of the baby."

The fact that RVMC covers a large and somewhat rural area can make timing a big factor in the case of a premature birth. Sohl said there are several methods used to get those mothers to the hospital.

"For instance, we utilize mercy flights in Medford," he said. "They will fly out to Lakeview or Klamath Falls to pick up moms. We also utilize ground transport from Yreka or Grants Pass. And helicopters and Cal-Ore Air Services fly to and from Gold Beach or Crescent City to transport mothers and their babies."

There are nine hospitals that feed into the RVMC area. In 2003, there were 4,687 deliveries of which 2,212 were at Rogue Valley, Providence and Ashland Community hospitals. Sohl noted that he doesn't think there are many regions in the west that are bigger geographically than the one RVMC services.

Sohl said the biggest advance in treating premature births has been human serfactin.

"That is a soap-like material in our lungs that keep our air sacs fully inflated," he said. "Newborn premature babies are deficient in that. It was initially collected in the early studies at caesarean section. A doctor in Bend, Dr. Alan Merritt, did a lot of that early study.

"After the collection of the fluid, they would centrifuge this fluid out and use it in studies and get the serfactin and spray it into the lungs of premature babies and found dramatic improved survival rates."

That practice ended with the identification of the HIV and Hepatitis viruses. Doctors then became very reluctant to use these kids of products collected from humans.

"Now, they have been able to genetically engineer that molecule and make it in bacteria," Sohl explained. "And now we have this genetically engineered product that can be sprayed down into a baby's lungs that are premature. That has made a big difference in allowing those babies to breathe."

And, another promising advance is now being tested and used in some circumstances.

"A natural hormone, progesterone, is being used in women who have delivered pre-term," Sohl said. "There has been two studies recently published, one using an injectable form and another using a suppository used in the vagina. They are given from 20 weeks to 34-36 weeks and have shown fairly dramatic decreases in the risk of pre-term labor for those moms compared to those given a placebo.

"It is still in its study phase and I think it would be ideal to have more information back about it. But I think, for a real high-risk patient, we are at a point where this is a good option."