The nearer the mothers lived to the main smelter, the higher was the babies' level of lead poisoning.
For babies born between 24 and 25 weeks resuscitation should be routine unless parents and doctors both agree there is no hope of survival, or if the babies' level of suffering outweighs its benefit in living.
It is likely that the follow-up period for the study was too brief to pick up on any changes in the babies' level of responsiveness that might have occurred.
According to the official Chinese Daily newspaper, medical tests performed on the babies found levels of estrogens circulating in their bloodstreams that are as high as those found in most adult women.
The developing baby is not great at processing caffeine and it can increase the baby's levels of stress hormones.
"Often if people have had lots of miscarriages or lost a baby, the levels of anxiety are much higher, they want a certain thing for a certain reason," she says.
During pregnancy, a particular type of antibody, called IgG, is transported from mother to baby directly across the placenta, so human babies have high levels of antibodies even at birth, with the same range of antigen specificities as their mother.
It points out that all three hospitals, including Bangor's Ysbyty Gwynedd, will continue to provide immediate short-term intensive care as well as special care baby units and high dependency units, but that a new service will be set up for babies needing further levels of care.
In these premature babies, even low levels of oxygen and methods of minimally invasive ventilation may disrupt the growth of the distal airways, a condition described as "new" bronchopulmonary dysplasia (BPD).
Health officials say it would apply to babies needing further levels of intensive care beyond the short term.
