Pfizer has launched a new COVID-19 vaccine trial specifically for pregnant women.

The drugmaker hopes to enroll 4,000 expectant mothers from around the world. Women who are over 18 and who are 24 to 34 weeks pregnant will be eligible.

Some of the women will be given the vaccine, while others receive a placebo shot. Once the women give birth, they will find out which shot they received. At that point, any mother who got the placebo will be offered the vaccine, too.

"Pregnant women have an increased risk of complications and developing severe COVID-19, which is why it is critical that we develop a vaccine that is safe and effective for this population," said Dr. William Gruber, Senior Vice President of Vaccine Clinical Research and Development for Pfizer.

"We are deeply thankful to the volunteers who are enrolling in the trial, and site investigators who are leading this work."

It's good news for expectant mothers, who until now have been excluded from vaccine studies.

Scientists with the National Institutes of Health recently published an article calling on vaccine developers to include pregnant women in their research.

"Pregnant and lactating persons should not be protected from participating in research, but rather should be protected through research," they wrote in the article published by the Journal of American Medical Association.

Pfizer's team will also follow the newborns for six months after birth. They hope to determine whether moms who receive the COVID-19 vaccine while pregnant ultimately transfer antibodies to their babies.

Researchers estimate this trial will wrap up by January 2023.

If you're interested in enrolling in Pfizer's clinical trial, you can find more information here.