New evidence suggests a drug used to lower blood sugar levels may also help extend the duration of preterm pregnancies in women with preeclampsia.
The findings from a small clinical trial, published Sept. 23 in the BMJ, showed that pregnant women who received the diabetes medication metformin prolonged their pregnancy by a week compared to those who received a placebo. Although this finding was not statistically significant, researchers said they are “cautiously optimistic” about the treatment of preterm preeclampsia.
“We hope that it will encourage others to test not only metformin but also other promising therapeutic candidates to treat and prevent preeclampsia,” study author Catherine Cluver, MBChB, FCOG, PhD, associate professor in the department of obstetrics and gynecology at Stellenbosch University in South Africa, said in an interview.
Preeclampsia, a condition that occurs about 1 in 25 pregnancies in the United States, happens when a woman develops high blood pressure and protein in her urine, according to the Centers for Disease Control and Prevention.
Preterm preeclampsia is a severe variant affecting 0.5% of all pregnancies, or 10% of those with preeclampsia, researchers wrote in the study. The condition is associated with more maternal and neonatal death and increases their risks of developing an illness.
Dr. Cluver said that when a mother develops preeclampsia, the lining of her blood vessels, or the endothelium, is affected and there are specific proteins in the blood that increase. Dr. Cluver’s preclinical study found that metformin improved endothelial function and decreased these biomarkers in laboratory work.
“We therefore set out to see if metformin could be used to prolong gestation in preterm preeclampsia,” she said.
For the study, Dr. Cluver and colleagues performed a double-blind, placebo-controlled clinical trial to compare the prolongation of pregnancies among women who were at least 26 months pregnant with preterm preeclampsia. They were treated with either 3 grams of extended-release metformin (90 women), or a matching placebo (90 women).*
In the treatment group, the average time from the start of the study to delivery was 17.7 days, compared to 10.1 days in the placebo group. The median difference was 7.6 days.
The researchers also found that 40% of women in the metformin group reached 34 weeks’ gestation compared with 28% of those in the placebo group. Fewer women in the metformin group delivered because of fetal indications such as fetal distress or other issues – 33% vs. 44%. However, the researchers said those results were not statistically significant.
They said they were cautiously optimistic when they found that the median time for prolongation of pregnancy in the metformin group was 17.5 days compared with 7.9 days in the placebo group, findings that were statistically significant.
Some adverse effects participants experienced while taking metformin during their pregnancy included diarrhea and an increase in nausea.
Although the study is important in maternal-fetal medicine and is a novel approach to preterm preeclampsia, the findings weren’t strong enough, but they point to the need for further study, said Victor Klein, MD, MBA, CPHRM, a specialist in high-risk pregnancy who was not involved in the study.
“Even though they did have an improved outcome, it wasn’t strong enough. It wasn’t long enough to prove that the medicine was useful or efficacious,” said Dr. Klein, vice chairman of obstetrics and gynecology at North Shore University Hospital, New York.
Metformin is also used to treat gestational diabetes, which is an “advantage of repurposing the drug is that it is likely to be safe,” the researchers wrote. They said longer term follow-up data might be worthwhile in future trials.
None of the experts had conflicts of interest to disclose.
*This story was updated on 10/6/2021.