(CNN) Cleveland Cavaliers star J.R. Smith spoke directly to his fans via video on Saturday to share some "very important news."

Speaking quietly to the camera, his wife, Jewel Harris Smith, announced the birth of their third daughter.

In stark contrast to their jubilant video reveal of Harris Smith's pregnancy in October, the couple appeared sad and deeply concerned in their poignant announcement.

"She's five days old today, and her name is Dakota, and she weighs 1 pound," Harris Smith said. "We decided to share with the world what's been going on with our family in the past five days. ... We know we're not the only family going through this, has been through this or who will ever go through it."

What is a preterm birth?

Dakota was born five months early, according to her mother, who did not explain the precise timing of the birth.

Preterm birth is when a baby is born before 37 weeks of gestation, according to Dr. Philippe Friedlich, chief of the division of neonatology and director of the center for fetal and neonatal medicine at Children's Hospital Los Angeles. A normal pregnancy can range from 38 to 42 weeks.

Preterm birth affected about one in every 10 infants born in the United States in 2015, the most recent statistical year tracked by the Centers for Disease Control and Prevention. Overall, the trend line has been decreasing from 2007 to 2014, due in part to a decline in babies born to teens. Mothers between the ages of 14 and 17 are more likely to deliver prematurely, according to one recent study

Between 2014 and 2015, there was a slight unexplained uptick.

The prognosis for preemies is very individual, with hopes for survival and well-being intertwined with the mother's condition and the reason for the prematurity, said Friedlich.

According to Dr. Anne Hansen, medical director of the neonatal intensive care unit at Boston Children's Hospital, the earliest that a baby can survive outside the womb is about 22 weeks gestation, and survival rates are extremely low during that week.

"Exact survival statistics are complicated to interpret, because many centers do not even offer resuscitation until 23 weeks," Hansen said.

For babies born very early, each and every week "can make a big difference in terms of prognosis," Friedlich said. In fact, there's a significant difference between 22 weeks and 23 weeks, with each week thereafter improving the prognosis.

"So at 23 weeks of gestation, nowadays, the prognosis is much better than a decade ago. ... Around 50 to 60% of those babies will survive," Friedlich said. Still, these infants "are prone to significant issues both while they're in the hospital and later on in life."

Possible complications

"The first week of life is very telling," Friedlich said. A baby who survives the first week of life has a much better chance of surviving in the long-term. Generally, premature girls have better rates of survival than premature boys.

"Most of those babies stay in the hospital usually for as long as their pregnancy would have been, plus usually one or two months extra, depending on the complications associated with the prematurity," Friedlich said.

These infants may suffer bleeding in the brain, cardiac and pulmonary complications and gastrointestinal issues. While in the neonatal care unit, they are also prone to infections.

After discharge, the first year of life is also "very telling" in terms of brain development, said Friedlich. A wide spectrum of outcomes is possible, be they very benign, normal or very severe, including mental and physical handicaps such as blindness and deafness.

Among the infants born at 23 weeks who survive, Hansen agreed, the outlook varies greatly.

"Roughly a third have major neurodevelopmental complications (mental retardation, cerebral palsy, blindness, deafness), another third have minor neurodevelopmental complications (learning difficulties, vision or hearing impairment), and the other third have fairly normal outcomes," she said.

Ultimately, it's impossible to predict an infant's future at birth, said Friedlich.

"What we tell parents is that usually, there will be ups and downs while they are in the hospital, but their long-term outcomes will really depend on many variables," he said.

Potential disparities

There are also racial and ethnic disparities, according to the CDC. In 2015, the rate of preterm birth among African-American women (13%) was higher than the rate among white women (9%).

This difference in rates is "significant," said Friedlich. "Especially in this country, because we think that there is not just a biological plausibility for it, but there is maybe disparity in access to care."

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Still, there are women who generally "tend to have premature infants compared to others," he said, with possible causes of prematurity rooted in medical issues affecting the mother or the placenta itself. In the video announcement, Harris Smith does not indicate possible reasons for her own premature delivery.

Smith and Jewel Harris married in August in a ceremony in his home state of New Jersey and tracked on his Twitter feed . At the time, they had two daughters, Demi and Peyton, according to Essence magazine