Originally Published: 11 AUG 21 13:04 ET

By Jacqueline Howard, CNN

(CNN) -- The US Centers for Disease Control and Prevention has updated its recommendation for pregnant people to get vaccinated against Covid-19.

Previously, the public health agency was vague in its recommendation. "If you are pregnant, you can receive a Covid-19 vaccine," previous guidance read. Now, the CDC is strengthening its guidance, recommending that pregnant women should be vaccinated against Covid-19, based on new data about the safety of the vaccines.

"COVID-19 vaccination is recommended for all people 12 years and older, including people who are pregnant, breastfeeding, trying to get pregnant now, or might become pregnant in the future," the new guidance reads.

"Evidence about the safety and effectiveness of COVID-19 vaccination during pregnancy has been growing. These data suggest that the benefits of receiving a COVID-19 vaccine outweigh any known or potential risks of vaccination during pregnancy," the CDC adds in the updated guidance on its website.

"We are not seeing a signal of safety concerns of the vaccine in pregnancy," Sascha Ellington, team lead for emergency preparedness and response in the CDC's Division of Reproductive Health, told CNN on Wednesday.

Pregnant women are at an increased risk of getting severely ill from Covid-19 and "adverse pregnancy outcomes, such as preterm birth," Ellington said. "This vaccine can prevent Covid-19, and so that's the primary benefit."

The agency said Wednesday that a new analysis of information from its V-SAFE database, used to track vaccine side effects and safety, found no increased risk for miscarriage among people who received either the Pfizer/BioNTech or Moderna coronavirus vaccines before 20 weeks of pregnancy. There were also no safety concerns among people who were vaccinated late in pregnancy -- for themselves or for their babies.

The rate of miscarriage among vaccinated pregnant women was about 13%, which is consistent with the rate that would be expected among unvaccinated pregnant women, Ellington said. In response to the myth that the vaccine could cause fertility issues, she said, "There are no data to indicate that the vaccine has any effect on fertility."

The website reflects this, also. "There is currently no evidence that any vaccines, including COVID-19 vaccines, cause fertility problems in women or men," it says.

The CDC says that it recommends Covid-19 vaccination for everyone ages 12 and older, including those who may be pregnant, breastfeeding, or who are trying to get pregnant.

As of July 31, only around 23% of pregnant women in the United States have received at least one dose of coronavirus vaccine, Ellington said. "The vaccine coverage of 23% does give us an indication that it is below where we want it to be," she added.

In late July, two leading organizations that represent obstetricians and gynecologists recommended that anyone who is pregnant should be vaccinated against Covid-19. The groups had previously said Covid-19 vaccines "should not be withheld" from someone because they are pregnant, but did not specifically recommend they get one.

The American College of Obstetricians and Gynecologists (ACOG) and the Society for Maternal-Fetal Medicine (SMFM) said their recommendations were based on safety evidence from thousands of pregnant women.

The associations also cite the country's low vaccination rate and the recent increase in cases.

The two groups urge their members to "enthusiastically recommend vaccination" to their patients.