Photo by Skip Lawrence Denise Kirkner-Vourlos' baby Markella Vourlos is shown Oct. 13 at 66 days old at Frederick Memorial Hospital.

For some women, the cervix dilates early, which Dr. Marilea Miller describes as "opening a door" for the baby. Miller is the medical director of the neonatal intensive care unit at Frederick Memorial Hospital.

Other mothers contract an infection or virus that causes early childbirth, and some elect to give birth early because of a condition like preeclampsia, which can cause organ failure in mothers.

Doctors said prenatal care is the No. 1 way to prevent premature birth. According to the National Women's Health Information Center, babies of mothers who get no prenatal care are three times more likely to have a low birth weight and five times more likely to die than those born to mothers who have regular care.

"Regular prenatal care is one of the best things that women can do to detect anything early," said Dr. Denise Kirkner-Vourlos, who practices at Capital Women's Care in Frederick .

Getting care early in the pregnancy is crucial, and the number of doctor visits over the course of the pregnancy will vary from woman to woman. Doctors will advise expecting mothers as to the frequency of their appointments.

The center also recommends refraining from smoking and drinking alcohol during pregnancy and even while trying to conceive.

But sometimes there's no explanation for an early birth. Kirkner-Vourlos gave birth to her daughter Aug. 8 at just 26 weeks gestation.

"I had care, but we have no idea why I went into labor," she said. "There's a small amount of women who just for some reason go into labor and deliver (early)."

Kirkner-Vourlos was transferred to Holy Cross Hospital because her baby was born too early for the FMH neonatal intensive care unit, she said. Her daughter is now back in the Frederick NICU and has grown from about 1 pound to almost 4 pounds, she said.

The special care nursery at FMH became a NICU in 2007, and can now care for babies born at 28 weeks or later. It has space for 30 babies, but it has never reached that capacity, Miller said. If a woman goes into labor before she has reached 28 weeks gestation, FMH will attempt to get her to another hospital before she gives birth.

"We try to do an in-utero transfer, but occasionally they do pop out," Miller said. About three or four babies are born before 28 weeks at FMH each year, she said.

According to a March of Dimes report release early this month, nearly 13 million infants, or 10 percent of all babies born worldwide, are born prematurely. More than 85 percent of these are in Asia and Africa.

North America reports about 500,000 preterm births per year, about 10.5 percent of all births. This is the second highest rate of preterm births in the world, second only to Africa's, according to the report. In 2008, 74 babies were born at 35 weeks or earlier at FMH, Miller said.

Babies born at 36 weeks or less are considered premature, but those born at 36 weeks usually don't end up in the NICU, Miller said. The lungs develop last, so many babies born before 36 weeks gestation have respiratory issues.

The length of a baby's stay in the NICU depends on when he or she is born, Miller said. A baby born at 28 weeks might stay 60 days, whereas a baby born at 32 weeks might stay 21 to 30 days, she said.

Most premature babies are ready for discharge at 36 to 37 weeks equivalent, Miller said.

"They do go home before their due dates almost always," she said.

Kirkner-Vourlos said she hopes her daughter will be able to go home by the end of October.

"She's had a very rocky course ... it's now just a feeding issue; she's learning how to take bottles and gain weight."

Parents have round-the-clock access to the NICU, but siblings and other family members are limited, Miller said. Visitors must wash their hands and put on sterile gowns before holding the tiny babies.

Kirkner-Vourlos visits her daughter in the NICU every day, and is waiting for the day she can take her home from the tiny hospital bed to her own crib.

"The NICU is just a roller coaster for every baby. You are not out of the woods until you're out the door," she said. "There's no words to describe what it's like for parents. It's stressful for parents and families."