BioEd Online

A record-breaking baby weighing a minuscule 280 grams has grown up into a healthy young girl, US doctors report this week. But experts fret that the 'miracle' baby may raise false hopes among parents about the outlook for their premature infants.

Madeline was the smallest baby ever to survive when she was born in Chicago in 1989. Her mother suffered from the pregnancy disorder preeclampsia, which starved the child of essential nutrients. So Madeline was born at 27 weeks, weighing the equivalent of three bars of soap. She was about a third of the weight of babies of a similar age and only a fraction of the three kilograms that newborns normally weigh after a full 40-week pregnancy.

Jonathan Muraskas, who helped deliver Madeline and is based at Loyola University Medical Center in Maywood, Illinois, says he thought at the time that she had a 60% chance of survival. Babies born with such drastically low birth-weights tend to suffer severe disabilities such as cerebral palsy, blindness or learning problems.

But 14 years on, Madeline is remarkably healthy, Muraskas and his colleagues report in the New England Journal of Medicine¹. She is small for her age, at only 136 centimetres compared with the average 163 centimetres, but she is in the top 20% for high school entrance exams scores. "I think her development is a miracle," Muraskas says.

Other researchers are concerned about the report. It may give a false impression that extremely premature and low birth-weight babies often survive to be healthy and happy, warns paediatrician Saroj Saigal of McMaster University in Ontario, Canada. Madeline is a "rare exception", she says.

Rather than looking at isolated cases, Saigal believes that parents' and doctors' expectations should be based on studies tracking a whole group of premature babies. In a series of studies on nearly 160 babies born in the range 500-1,000 grams, for example, she and her colleagues have found that over half suffer severe intellectual difficulties at adolescence.

Ahead of their time

A handful of key medical advances over the last 30 years help premature babies to survive where once they would have died. Mothers in premature labour are given steroids to accelerate the development of their child's lungs. Newborns are put on drugs called surfactants, which open up the lungs, and advanced ventilators are used to help them breathe.

Even so, babies born at 23 weeks are on the threshold of survival, partly because their brains, guts and lungs are too immature to cope. At this age, less than 40% of infants survive, and the vast majority of those that do will go on to develop major disabilities. Experts say this 23 week boundary is unlikely to be pushed back.

By 27 weeks of age, however, babies' organs have matured to a point where over 90% survive and only a small fraction suffers severe handicaps. The reason Madeline thrived at such a minuscule weight, experts say, is because she was born at this later stage.

All babies born very early would die without medical help, however, so parents have to make the difficult choice of whether to resuscitate them. And doctors are concerned that rates of disability are not improving as much as rates of survival.

Because of this, one of the most pressing challenges for medical researchers is to try and identify which mothers are likely to go into premature labour, says Saigal: "If we could predict that then we could do something about it."