When tiny premature babies grow a little older in the womb and after birth, their brains show signs of getting more developed—like neurons getting better connected and insulated—as seen by a special brain scan measure.

In very small premature babies, the brain chemical ratio measured in certain areas doesn’t tell us whether they’ll develop normally or have problems later, even though this ratio naturally goes up as the baby gets older.

Doctors looked at brain chemical levels in tiny premature babies and found no link between those levels and how well the babies developed mentally or physically by the time they were 18 to 24 months old.