LONDON -- Pregnant women in Britain should get a COVID-19 vaccine made by Pfizer or Moderna because there is more real-world data to show they are safe, the British public body that advises on vaccinations said on Friday.

The Joint Committee on Vaccination and Immunisation (JCVI) said around 90,000 pregnant women had been vaccinated in the United States, mainly with the two American vaccines, without any safety concerns being raised.

"Based on these data, the JCVI advises that it is preferable for pregnant women in the U.K. to be offered the Pfizer-BioNTech or Moderna vaccines where available," it said. "There is no evidence to suggest that other vaccines are unsafe for pregnant women, but more research is needed."

Pregnant women had previously been advised against taking the vaccine in Britain because not enough information was known about the impact.

"I encourage all pregnant women when they are called to get the jab to come forward and discuss the benefits and risks of the vaccine with a trusted source like their GP (family doctor), obstetrician or midwife," Health Secretary Matt Hancock said.

Britain recently advised that all under 30s should be given alternative vaccines to the Oxford/AstraZeneca shot if possible because of a "vanishingly" rare side effect of blood clots in the brain.

(Reporting by Kate Holton, editing by David Milliken)