Progesterone

PROGESTERONE

The hormones progesterone administered by injection or virginally to pregnant women, has been helpful in reducing the chances that a woman who has had one preterm birth will have another.

Two previous trials have also found progesterone useful in preventing preterm births among women with a short cervix, another known risk group. But those studies, using the virginal form of the drug, looked only at women who had a cervical length of less than 20 millimetres- only 2% of the population.
 

Scientists have hoped the hormones would benefit even more women, making a significant dent in the number of preterm births each year. Reports show that progesterone in its injected form does not work for a much larger risk group: the 10% of women with a cervix shorter than 30 millimetres. These women have about the same risk of having a preterm birth – around 25% - as those who have already had one.

The study emphasizes that because progesterone works for one group at risk for preterm birth doesn’t mean that it can automatically be extended to others, William A. Grobman, a professor of obstetrics and gynecology at North western.

Researchers randomly assigned 657women to a weekly injection of a form of progesterone or to a placebo shot. All were pregnant for the first time with a single baby, and each had a cervical length of less than 30mm at 16to22wks gestation. The women were followed through discharge from the hospital.

The scientist was unable to find any significant differences in birth outcomes between the two groups. Of those who took the progesterone, 25.1% delivered prematurely (at less than 37 weeks) and so did 24.2% of those on the placebo.

The average gestational age at delivery was the same in each group. The numbers of deliveries at less than 35wks and less than 28wks were practically the same in those who had taken the drugs and those who had taken the placebo.

By more than a dozen different measures of material and fetal health, too, the researchers could find no difference between the groups. Even the side effects – mostly pain or soreness at the injection site- were the same.

Some researchers like Sonia S. Hassan, the associate dean for maternal, prenatal and the child at wayne state university in Detroit, advocate cervical length screening for all pregnant women

If it’s found to be short, she said, they should receive vaginal progesterone. The injectable form is commonly used for women with a prior preterm birth. I would advise women to speak with their physician to see if they are candidate for that.

The vaginal form of the drug has not been tested in the larger group of women with a cervix shorter than 30mm only in the relatively few women with a cervix shorter than 20mm.

Grobman noted that the health and economic burden of preterm birth is enormous.

It’s incredibly important to investigate which risk groups can benefit and whether our strategies in general can be useful in preventing preterm birth, he said.