Drug to Help Prematurity Flops

Delaying premature labor with nifedipine apparently not worthwhile

(RxWiki News) A full pregnancy term is 38 to 40 weeks. If it seems like the baby might come sooner, especially before the 34th week, doctors do what they can to prevent a premature birth.

Women who have symptoms of labor before 34 weeks of pregnancy are often given a medication to prevent going into labor. That delayed labor process is called tocolysis. A common medication for it is nifedipine.

The goal is to delay labor at least two days so a steroid can be given to help the baby develop faster for delivery. A recent study looked at the outcomes of babies when tocolysis is extended with nifedipine for more than 2 days.

Researchers found nifedipine does not improve outcomes for the newborn just before and just after birth.

The medication may still be helpful for those two days after early labor signs, but there is no apparent value in continuing it after those days.

"Attend all prenatal appointments."

The study was led by Carolien Roos, MD, from the Department of Obstetrics and Gynecology at Radboud University Nijmegen Medical Centre in the Netherlands.

The researchers compared two groups of pregnant women who showed signs of early labor between the 26th and 32nd week of pregnancy.

All the 406 women had been given tocolytics (drugs to cause tocolysis) to delay their labor for 48 hours and a dose of corticosteroids. The corticosteroids are given to improve the baby's lung maturity more quickly before possible early delivery.

The tocolytic delays the labor to give the steroid time to work and to provide time for the woman to be transferred to a hospital with a neonatal intensive care unit (NICU).

Then 201 of the women were given a daily dose of 80 mg of nifedipine for 12 days. Nifedipine is a type of medication called a calcium-channel blocker.

It's approved for other conditions, but the goal here was to see if it would further delay labor and delivery for the pregnant women.

The other 205 women were given a placebo (fake pill) for 12 days. Then the doctors looked at the rate of newborn death and several other complications in the babies.

These complications included infection, chronic lung disease, bleeding in the brain, other types of brain injury and a condition called necrotizing enterocolitis, when tissue in the baby's intestines dies.

The results showed that there were not any substantial differences in the rates of complications between the two groups of women.

In the group who received the additional doses of nifedipine, 11.9 percent had babies with a serious complication. The rate among women who received the placebo was 13.7 percent.

The rate was higher among the women who received the placebo, but not high enough to show that the medication in the other group actually made any difference. The difference could have been attributed to statistical chance.

The researchers therefore concluded nifedipine's "use for maintenance tocolysis does not appear beneficial at this time."

The research was published January 2 in JAMA. The research was funded by a grant from ZonMw, the Netherlands Organization for Health Research and Development Healthcare Efficiency Program.

One author has a pending grant from CSL Behring. Another author has offered expert testimony in courts and lectures for payment, receives royalties on a textbook about obstetrics, and holds private, unrelated stocks. No other disclosures were noted.

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Review Date: 
January 2, 2013