— Officials with the North Carolina Board of Nursing said Friday that they are investigating a complaint against a midwife at a Cary birthing center where three babies have died since October.

The board received the complaint Friday morning, the day after WRAL Investigates reported on the deaths.

Officials declined to release details. WRAL Investigates found that Baby+Co. had a midwife resign within the last few months. It was not clear if that person was the target of the complaint.

Four babies have died at Baby+Co. in Cary since the center opened in 2014. One death occurred in 2015, two more happened last fall and a fourth one occurred in February.

This month, a fifth newborn was rushed to Duke University Hospital's neonatal intensive care unit after showing distress during delivery at the Cary center.

Baby+Co. halted all deliveries after that latest incident and is referring all expectant mothers to nearby WakeMed Cary while officials review the center's protocols.

"Any time you hear of a baby that's died, it's tragic, and it certainly needs to be investigated. That number of deaths in such a short time span is certainly concerning and unusual," said Becky Bagley, director of the midwifery education program at East Carolina University.

According to the American Association of Birth Centers, 0.4 newborn deaths occur per 1,000 women at birth centers. With the recent cluster of deaths, the mortality rate at Baby+Co. in Cary is 2.87 per 1,000 women.

"My personal reaction is shock and, of course, sadness and sympathy," said Debra Fiore, a certified nurse midwife with 17 years of experience at birth centers, hospitals and homes. "I've never heard of this. I mean, this many in this short a period of time, I've just never encountered it."

Baby+Co. also suspended deliveries and investigated after the deaths last fall and again in February but then resumed them within weeks.

Fiore and Bagley said a more thorough investigation is needed this time.

"The investigation may prove there's nothing that could have been done. That sometimes happens," Bagley said. "But if there's something that could have been done, we need to address it, and we need to learn from it."

Both women said they hope the newborn deaths don't scare women away from birthing centers, which have seen explosive growth in recent years.

In 2015, 624 babies were delivered in birth centers statewide. By last year, that figure had almost doubled, to 1,193.

"The last thing we want to see happen is the closing of birth centers," Fiore said. "We want to see more birth centers opened."

"Birth centers are a very safe place to deliver," Bagley said, citing a collection of studies that found no significant difference in newborn mortality rates at birth centers versus hospitals for women with low-risk pregnancies.

"[Newborn deaths] happen in the hospital. They happen in any birth setting. Things can happen. That's just a fact," she said. "The birth centers that are in the United States that are accredited are very safe places for women to deliver."

Baby+Co. in Cary is accredited, and its staff is properly licensed with the state.

Still, there's no direct regulation of the centers by the state Department of Health and Human Services. They are required to have physician oversight, but a doctor doesn't have to be on site, and the Board of Nursing investigates complaints against nurse midwives.

Parents can request a birth center's credentials and outcomes.

Margaret Buxton, a certified nurse midwife and clinical director for Baby+Co., said center staff want to know what went wrong as much as parents do.

"It's a tragedy. Loss is a tragedy for every family. So, it would be wonderful if we could make it zero all the time. It's not possible, honestly," Buxton said.