More young and healthy pregnant people are ending up hospitalized on ventilators, delivering babies prematurely and sometimes dying from COVID-19 during the delta-fueled spike in cases.

Doctors across the country are reporting this trend, not seen in previous surges, largely in the South but also in states like California and Washington. As of Aug. 14, 76.2% of pregnant people were unvaccinated.

Pregnant women with COVID-19 are 15 times more likely to die, 14 times more likely to need to be intubated, and 22 times more likely to have preterm birth than those who are uninfected, according to a study published this month in JAMA Network Open. "I have not seen risks like this," said Linda Eckert, professor of obstetrics and gynecology at the University of Washington.

Reluctance to get the shots has been widespread among the pregnant population because they were excluded from clinical trials for the Pfizer Inc.-BioNTech SE, Moderna Inc., and Johnson & Johnson vaccines. Studies on pregnant women began in February, and evidence has shown no increased risk of miscarriage from the shots. U.S. health officials this month stepped up calls for pregnant people to get vaccinated.

"Now we have a lot more compelling data about the safety of the vaccine in pregnancy and we have amazingly compelling data about how dangerous it is to get COVID when you're pregnant," Eckert said.

The low numbers of pregnant people who are vaccinated and the delta variant have "created this perfect storm of pregnant people getting extremely sick and being hospitalized, and even requiring care in the intensive care unit," said Alison Cahill, a professor of women's health at the University of Texas at Austin Dell Medical School and maternal-fetal medicine specialist at the school's Women's Health Institute. "We have very, very busy services with patients extremely sick from COVID."

Gabriella Nardi-McGee, who is six months pregnant and lives in New York City, got her first vaccine dose after the end of the first trimester of her pregnancy after initially worrying about harming her unborn child. However, she also was concerned about exposing her immunocompromised mother to the virus and "did not want to be in a hospital and not be vaccinated," she said. "That really scared me."

Judette Louis, chair of the University of South Florida College of Medicine Obstetrics and Gynecology, said the vast majority of pregnant people getting hospitalized with COVID are unvaccinated.

"We did have a couple of vaccine breakthroughs that did end up needing to be hospitalized, but they did not end up on the ventilator," Louis said.

People often undergo immune changes during pregnancy that can increase vulnerability to a severe type of COVID, potentially with respiratory issues, said Shweta Patel, an obstetrician and gynecologist in Florida.

In the study published in JAMA, University of California, Irvine, doctors and a statistician analyzed a clinical database of more than 650 academic hospitals in the U.S. to compare patients who gave birth with or without COVID-19 between March 1, 2020, and Feb. 28, 2021.

Of those cases, 5.2% of those giving birth with COVID were admitted to the ICU, compared with 0.9% of women without the virus; 1.5% of those with COVID were intubated, compared with 0.1% of women without the virus. Additionally, 16.4% of women with COVID delivered at less than 37 weeks, compared with 11.5% of those without the virus.

"Sometimes the illness can be significant enough such that we have to deliver folks early and when that happens, then that newborn baby who's delivered extremely prematurely takes on all of the risks of a very preterm delivery that can be lifelong morbidities and even death," Cahill said.

Ronald Reagan UCLA Medical Center in Los Angeles has seen a lot of pregnant people admitted to the ICU throughout the pandemic, said Nida Qadir, associate director of the hospital's medical ICU. It is one of the few facilities in the Los Angeles area that can put patients on extracorporeal membrane oxygenation (ECMO), a machine that bypasses the heart and lungs to allow the body to heal.

Now that there are more cases overall, there are even more pregnant COVID patients in her ICU.

People who have to deliver early and end up on ECMO have a "long course to recovery," said South Florida College's Louis.

Taking care of severely ill COVID-19 patients can be more challenging if they're pregnant. One important way to help patients in respiratory distress involves putting someone on their belly, known as proning. "While we're able to do it, it for obvious reasons becomes more difficult if somebody is further along in their pregnancy," Qadir said.

Doctors also need to keep oxygen levels higher for pregnant patients because "we are trying to keep in mind oxygen delivery to the fetus, which is very sensitive to changes in oxygenation," Qadir said.

Qadir took care of one young woman who had an uncomplicated pregnancy and was athletic before getting COVID. The woman had to deliver her baby prematurely, "nearly died so many times," and was in the hospital for months before she was able to go home.

"We cannot predict who is going to have that severe COVID pneumonia respiratory failure outcome," said Christopher Robinson, chair of obstetrics and gynecology and director of maternal fetal medicine at East Cooper Medical Center in Mount Pleasant, S.C. "The only thing that appears to be suggestive of who is safe and who is not is vaccination history."

When Molly Wadzeck Kraus from Trumansburg, N.Y., was considering getting vaccinated while pregnant, safety data still wasn't available. "I struggled with the decision of whether or not to do it," she said.

Her obstetrician said it was up to her. When data came out, Wadzeck Kraus discussed it again with her obstetrician and decided to get the vaccine. Four weeks ago, she gave birth to a healthy baby girl.

"Even if there was a risk of miscarriage, I would've much rather risked that than risk me getting COVID and dying and leaving my two children I already have without a mom," Wadzeck Kraus said.