Women who take Viagra during the first stages of labor are half as likely to require an emergency cesarean, according to a new clinical trial.

The drug sildenafil, which is sold under the brand name Viagra, may increase blood flow to the fetus in much the same way as it does to the penis in men with erectile dysfunction, note researchers whose findings are published in the American Journal of Obstetrics and Gynecology.

Cesarean delivery is a surgical procedure to deliver a baby through incisions in the abdomen and uterus, according to the Mayo Clinic. Cesarean delivery can be planned in advance for a number of reasons, as well as an emergency option for when things do not go according to plan during vaginal birth. This can include a stalled labor where the cervix isn’t opening enough, a baby is in distress or in an abnormal position, or other health concerns. During labor, contractions reduce blood flow to the placenta, which may result in placental insufficiency, depriving the fetus of essential nutrients and oxygen. This is a rare but serious pregnancy complication that can lead to life-threatening complications for the infant and mother, notes Birth Injury Guide. In total, about two in every five cesarean deliveries are unplanned due to complications that put the baby at risk, according to Health Direct. 

To test their hypothesis, Australian researchers gave sildenafil to 150 pregnant women and placebo pills to another 150 women in early labor between September 2015 and January 2019 at Mater Mother’s Hospital in Brisbane. Women were between the ages of 18 and 50 experiencing an otherwise healthy pregnancy and were planning a vaginal birth. Doses were given hourly beginning at 50 milligrams going up to 150 milligrams.

The sildenafil group were 51 percent less likely to require emergency caesareans and saw 43 percent fewer cases of irregular heart rate patterns, which are indicative of a fetus being in distress. However, the drug’s impacts on fetal scalp sampling rates and adverse outcomes after birth remain inconclusive and 2.6 percent of sildenafil or its byproducts were detected in cord blood. Additionally, both groups of women experienced higher rates of induced labor than expected, which means they were already at higher risk for fetal distress and reduced the likelihood that they would require an emergency cesarean birth.

The authors note that sildenafil is not shown to prevent other health conditions that may impact a fetus, such as cord prolapse, placental abruption, or uterine rupture – all of which are strongly associated with a severe hypoxic injury. The outcomes of sildenafil on birth are still unknown and further trials are required to determine whether it may be connected with stillbirth, death, and disability following birth.

“Despite its promising results, this Phase II trial was underpowered to evaluate the 458 effects of sildenafil citrate on maternal and neonatal outcomes. Much larger 459 numbers are therefore urgently needed Phase III trials, endorsed by key stakeholders,” wrote the authors.

To broaden the findings and understand the greater implications of sildenafil during labor, the researchers say they are planning a bigger trial with more than 3,000 women at 16 hospitals across Australia, reports New Scientist.