Neonatal and Five Year Outcomes after Birth at 30-34 Weeks of Gestation
Abstract & Commentary
By John C. Hobbins, MD, Professor and Chief of Obstetrics, University of Colorado Health Sciences Center, Denver, is Associate Editor for OB/GYN Clinical Alert.
Dr. Hobbins reports no financial relationship to this field of study.
Synopsis: Authors evaluate the rates of in-hospital death, neonatal complications, and 5-year outcomes of infants born at 30-34 weeks of gestation.
Source: Marret S, et al. Neonatal and 5-year outcomes after birth at 30-34 weeks of gestation. Obstet Gynecol.2007;110:72-81.
In the latest issue of Obstetrics and Gynecology there were 3 papers, loosely tied together, that should provide important guidance to clinicians dealing with preterm labor (PTL). One article will be the source for the primary review, but the others will be folded into the comments sections.
I have found myself telling patients that once their pregnancies have reached 32 weeks, the fetus/infant represents a nursery "slam dunk" for today's neonatologists. The following article demonstrates how inaccurate that concept is.
Marret et al compiled data from infants born in nine regions in France during 1997 and added follow-up data from these infants at 5 years of age. The author concentrated on those born between 30-34 weeks of gestation.
Neonatal morbidity dropped from 8.1% to 0.4% between 30 and 34 weeks. Respiratory distress syndrome (RDS) decreased from 43.8 % to 2.6 %, perinatal infection from 7.2 % to 2.6 %, and severe "white matter injury" from 5.5 % to 1.3 %. At 5 years of age the incidence of cerebral palsy (CP) and cognitive impairment in children born between 30 and 34 weeks dropped at each week of gestation from 6.7 percent to 0.7%, and from 35.3% to 23.9%, respectively.
It is clear from these data that being born, even at 34 weeks, is not ideal for immediate health and longer term development, thereby leading to the conclusion that we should continue doing everything we can to keep these babies from delivering early. Although this is a very logical interpretation, it should be pointed out that there may be more to the story. For example, CP and impaired childhood development can be linked directly in some cases to intrauterine infection, which often was the cause of the associated preterm labor and delivery. Since it would be far worse to attempt to keep fetuses exposed to infection in utero than to have them exposed to the complications of prematurity alone in today's improved neonatal environment, it seems that we should be very selective in our attempts to stop preterm labor. That said, information from recent investigation involving cervical length, various interleukins, amniocentesis, and other clinical tip offs should allow us to identify those in whom an aggressive attempt should be made to prolong pregnancy.
In the last 5 years most studies have yielded negative results regarding our ability to stop preterm labor, but very recently there have been encouraging results from transdermal nitroglycerine (GTN) and nifedipine in stopping preterm labor. In the same issue of Obstetrics and Gynecology, a randomized trial was published comparing nifedipine and magnesium sulfate (MgSO4) to stop contractions for 48 hours in patients with preterm contractions. They found that, although MgSO4 was slightly better in achieving that one goal, there was no difference in rate of delivery within 48 hours (7.6% vs 8.0%) or average time of delivery (35.8 weeks vs 36 weeks). MgSO4 achieved the dubious distinction of much higher adverse maternal effects and resulted in a doubling of neonatal nursery days.
Last, another study in the same journal comparing dexamethasone and betamethasone to reduce RDS, found no difference in their abilities to do this, but dexamethasone was associated with a lower rate of neonatal interventricular hemorrhage (IVH).
So, to summarize:
- It does make sense to try to keep fetuses in utero up through 34 weeks of gestation, as long as an aggressive attempt is made to rule out intra-uterine infection.
- There is now more evidence that we should move away from MgSO4 as a tocolytic.
- The newest study pitting dexamethasone against betamethasone shows the former medication to be at least as effective in stimulating pulmonic maturity, and may be better at preventing IVH, (and, it is cheaper).