The World Health Organization on Friday changed its guidelines for pregnant women considering a Covid-19 vaccine and abandoned opposition to immunization for most expectant mothers unless they were at high risk.

The change came after an outcry from WHO’s previous stance that the organization “did not recommend vaccinating pregnant women with the vaccines manufactured by Pfizer-BioNTech and Moderna”.

Several experts expressed their disappointment with the WHO’s earlier position on Thursday. The experts found that this was inconsistent with the guidelines of the U.S. Centers for Disease Control and Prevention on the same topic and would confuse pregnant women who are looking for clear advice.

The vaccines manufactured by Pfizer-BioNTech and Moderna have not been tested on pregnant women, but have not shown any harmful effects in animal studies. According to experts, the technology used in the vaccines is generally known to be safe.

The WHO’s new wording reflects this information:

“Based on what we know about this type of vaccine, we have no particular reason to believe that there are any specific risks that would outweigh the benefits of vaccination for pregnant women.” The recommendation is now closely aligned with the position of the CDC.

Experts praised the postponement and welcomed the agreement between the world’s leading public health organizations on this important issue.

“I was very pleased to see that WHO has changed its guidelines for offering the Covid-19 vaccine to pregnant women,” said Dr. Denise Jamieson, an obstetrician at Emory University and a member of the Covid Expert Group at the American College of Obstetrics and Gynecology. The association was among the many women’s health organizations that urged Pfizer and Moderna to speed up vaccine testing in pregnant women.

“The WHO’s more permissive language is an important opportunity for pregnant women to get vaccinated and protect themselves from the serious risks of Covid-19,” said Dr. Jamieson. “This impressively rapid overhaul by WHO is good news for pregnant women and their babies.”

Pregnant women have traditionally been excluded from clinical trials, so there is a lack of scientific data on the safety of drugs and vaccines in women and their unborn children. Vaccines are generally considered safe, and pregnant women have been encouraged to get immunized against influenza and other diseases since the 1960s, even though rigorous clinical studies have not been conducted to test them.

Pfizer will test its vaccine in pregnant women over the next few months, according to a company spokeswoman. And Moderna plans to set up a registry to monitor side effects in women who have been immunized with the vaccine.