Previous studies showed the drug to have a positive effect on the growth of babies
A Dutch study into the use of viagra by pregnant women has been halted after 19 babies died.
The research by the Amsterdam University Medical Centre was to study the effect and safety of the drug sildenafil, sold as the brand name Viagra among others, which was given to pregnant women whose babies had a severe growth limitation.
Previous studies have shown sildenafil had a positive effect on the growth of babies.
The first results of the current study showed that there may be adverse effects for the baby after birth.
The study started in 2015 and focused on pregnant women whose babies had a serious growth limitation in early pregnancy.
There is no known therapy to date to help these babies grow.
Sildenafil is a blood vessel removal that may improve the function of the placenta, as was shown in previous research.
The study said this can stimulate the growth of an unborn child.
Half of the participants received tablets with sildenafil, the other half got a placebo.
But an interim analysis by Amsterdam UMC showed that sildenafil "may be detrimental" to the baby after birth.
The chance of lung disease appeared to be greater, and the chance of death after birth seemed to have increased, the medical centre said.
"The researchers found no positive effect for the children on other outcomes", it added.
It said the mothers had no adverse effect to the drug.
At the time of cessation, 183 women were involved in the study - of whom just over half had taken the drug.
In the sildenafil group, 93 women participated.
In this group 19 babies died, with 11 of these due to a possible lung disease - in the form of high blood pressure in the lungs.
Six babies also had this lung disease, but did not die.
The researchers note that Pfizer Viagra and Pfizer Sildenafil were not used as medication in the study.