The Centers for Disease Control and Prevention recommended Wednesday that pregnant people be vaccinated against the coronavirus, updating its advice after it found no increased risk of miscarriage among those who have been immunized.

With vaccination rates low among pregnant women, the new guidance officially moves the CDC off its previous neutral stance on whether immunization is safe for them. It comes two days after more than 20 health organizations urged vaccinations for pregnant women, those who have recently been pregnant and those who plan to become pregnant. And the statement arrives more than three months after CDC Director Rochelle Walensky said immunization during pregnancy is safe.

Just 23 percent of pregnant women have received at least one shot of vaccine. The CDC advice applies to all three vaccines, though the one-shot Johnson & Johnson version has not been studied as much as the versions produced by Pfizer-BioNTech and Moderna, an official said.

“CDC encourages all pregnant people or people who are thinking about becoming pregnant and those breastfeeding to get vaccinated to protect themselves from COVID-19,” said CDC Director Rochelle Walensky said in a statement. “The vaccines are safe and effective, and it has never been more urgent to increase vaccinations as we face the highly transmissible Delta variant and see severe outcomes from COVID-19 among unvaccinated pregnant people.”

Previously, the health agency had said that pregnant women were “eligible” for the vaccine. Sascha Ellington, the team lead for the Emergency Preparedness and Response team in CDC’s Division of Reproductive Health, said the agency had no reason for concern, but in the absence of data previously “did stop short of a stronger recommendation in pregnant women.”

Brenna Hughes, a maternal-fetal medicine physician and member of the Society for Maternal-Fetal Medicine covid-19 Task Force, noted that misinformation about the vaccine’s effect on pregnancy and fertility has proliferated.

“There’s a lot of misinformation out in the world and that certainly has not helped vaccination efforts in any population,” Hughes said. “And among pregnant individuals, patients are worried about themselves as well as their babies. They have a lot more to consider.”

With cases of the delta variant of the virus soaring to a daily average of nearly 118,000, according to data analyzed by The Washington Post, the new advice might persuade some women to immunize themselves against covid-19, the disease caused by the virus.

Ellington said the updated guidance was informed by new data on the vaccine’s effects on pregnant women, increased risks of covid-19 in pregnancy and low vaccination rates among the pregnant population. The rise of the delta variant was also a factor.

“Taken together,” she said, “the time was right to come out with a stronger recommendation to hopefully increase the vaccination rates in pregnant women and hopefully protect them against covid-19.”

In a similar effort Monday, groups including the American College of Obstetricians and Gynecologists and the American Academy of Pediatrics said data shows that the vaccine is safe and effective when administered during pregnancy and has no impact on fertility.

“Pregnant individuals are at increased risk of severe COVID-19 infection, including death,” the organizations said. “With cases rising as a result of the Delta variant, the best way for pregnant individuals to protect themselves against the potential harm from COVID-19 infection is to be vaccinated.”

The CDC said a new analysis of data from the pregnancy registry did not find an increased risk for miscarriage among people who received the mRNA vaccine before 20 weeks of pregnancy; miscarriage rates were similar to the expected rate generally. Previous findings did not reveal any safety concerns for pregnant people who were vaccinated late in pregnancy or for their infants.

Other research has shown that covid-19 presents a significant risk of complications for pregnant women, including preterm birth. Pregnant women who contract the virus also appear to be at more likely to require admission to intensive care and use of ventilators.

“It is a really concerning paradox that people who are at potentially higher risk than the general population are less likely to get vaccinated,” Hughes said.

She said the new CDC guidance should put minds at ease “that in fact they should get the vaccine, and perhaps it would be even more important for them to get the vaccine when pregnant.”