Narrator: This is Science Today. If a baby is born at 41 or 42 weeks of gestational age, the probability of a neonatal death is higher than if that baby was delivered at 38, 39 or 40 weeks gestational age. Obstetrician, Dr. Andrew Caughey of the University of California, San Francisco, says this is due to what neonatalogists call post-maturity syndrome.
Caughey: That babies who stay inside the uterus a little bit too long - it's almost like they get overcooked. You can imagine if you think of the bun in the oven, you leave the bun in a little bit too long and we see that these kids look like they've actually been losing weight for the last week or so, these post maturity kids. They actually are thinner rather than chubbier. They have a much higher rate of meconium, the baby's first bowel movement inside, their skin is a little peely. It's again, almost like they're a little overcooked.
Narrator: Meconium can cause respiratory problems, such as clogged lungs. Caughey's national study recommends delivery at 39 or 40 weeks. For Science Today, I'm Larissa Branin.