A BABY born more than four months before her due date has become the youngest premature baby to survive. The girl was born after only 21 weeks and 5 days’ gestation, at Samsung Medical Centre in Seoul, South Korea, and is now a healthy 5-year-old.
In 2012, the girl’s 38-year-old mother was rushed to hospital because the membrane sac encasing her unborn twins had burst – a sign of impending labour. She was told that her twins, which had been conceived by IVF, were extremely unlikely to live, and that active life support is usually only given to preterm infants born at 25 weeks or later.
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However, the woman and her husband had a long history of infertility issues and IVF failures and urged their doctors to try to support the twins. The doctors agreed, and gave the mother steroids to try to speed up the development of the twins’ lungs.
Intensive care
When she gave birth the next day, the babies weighed just under half a kilogram each, and were 30 centimetres long. Most full-term infants born at 40 weeks weigh about seven times as much, and are 50 centimetres long.
The newborns were placed on ventilators and fed via tubes into their stomachs, because at only 12 days past the halfway mark of pregnancy they couldn’t breathe or swallow food on their own (see “Stages of development“). The male twin died two months later from an infection, but the female twin survived and was discharged from hospital six months after she had been born.
Since then, she has mostly developed normally. She is smaller than other children her age, but has normal language, cognitive and social skills. She needs to wear glasses, but she has no breathing problems or signs of physical disability (Journal of Korean Medical Science, ).
Her good health may be due to the steroids she was given before she was born and her gender, says her doctor of Samsung Medical Centre. Many previous studies have found that premature babies are , although the reasons for this are unclear.
The previous record for the youngest surviving premature infant was a girl born in the US at . She was also conceived via IVF.
Last month, at Baylor College of Medicine in Texas reported the case of a 2-year-old girl who was surviving well after being born at about . However, her exact gestational age at birth couldn’t be determined because she was conceived naturally, not by IVF. The estimate was based on her mother’s last period and ultrasound dating, which has an error margin of about .
at Royal Prince Alfred Hospital in Sydney, Australia, says these cases highlight how far neonatal care has advanced in recent decades. When he started training as a neonatologist in the 1970s, babies born between 30 and 34 weeks often didn’t survive, he says. “Now they mostly sail through without any problems.”
Big improvements were initially made with the introduction of mechanical ventilators and giving the mother steroids during labour. The use of lung surfactant has helped premature babies breathe using their slightly stiffer lungs.
More recently, additional improvements have been made by disconnecting babies from ventilators and IV nutrition lines as soon as possible, to prevent lung damage and reduce the risk of infection. Doctors have also found that waiting a minute to clamp the umbilical cord seems to improve health. This may be because it allows and immune cells to flow into the baby from the placenta.
However, babies that survive extremely premature birth can create false hope for other parents, says Evans. Only 23 per cent of babies born at 22 weeks who receive intensive care survive, and there is not enough data to know what the overall chances of survival for a baby born at 21 weeks, like the Korean girl, are (see Graph).
“There’s no doubt that survival rates are improving for extremely premature babies”
Of the very premature babies that survive, end up having severe neurological issues. “There’s no doubt that survival rates are improving for these extremely premature babies, but the disability rates are still quite high,” says Evans. “Their brain is still a rudimentary structure, their lungs haven’t properly developed yet, and they have no defence mechanisms against infection, so it’s challenging to nurse them through that.”
Most premature babies in now receive active support if they are born at 25 weeks or later, while decisions about those born at 23 to 24 weeks are made on a case-by-case basis. Few neonatal units offer interventions for babies born at 22 weeks or less.
The increasing survival of very premature babies may have implications for abortion laws, which have time limits to prevent the termination of fetuses that would be capable of living outside the womb. In the UK and parts of Australia and the US, abortions are legal up to 24 weeks, which has been considered the threshold of viability.
In June, the British Medical Association reaffirmed its support for this cut-off. “It is the BMA’s view, based on the peer-reviewed published UK data, that there is no evidence of significant improvements in the survival of extremely preterm infants to support reducing the 24 week time limit for legal abortion on this basis,” it wrote .
However, Evans thinks this may change. “I think many neonatologists would now say that 24 weeks is a bit high and 20 weeks would probably be a better cut-off,” he says. “But it is a difficult ethical thing.”
Stages of development
If a baby is born prematurely, it might not yet have reached key milestones of development.
Weeks 1 to 12
Basic structures of organs, limbs, eyes, nose, lips, ears, fingernails and genitals start to form.
Weeks 14 to 18
Toenails, taste buds, hair follicles and sweat glands form. Lung airways develop fine branches, and ear canal becomes fully formed.
Weeks 20 to 24
Mammary glands form. Grooves appear on brain surface and start to fold. Lung alveoli begin to form, allowing gas exchanges with bloodstream.
Weeks 28 to 40
Organs continue to grow. The brain undergoes complex folding, testes descend, and eye lenses develop.
This article appeared in print under the headline “The youngest survivor”
