Researchers have discovered that a chemical released at the time of birth plays a major role in protecting a newborn's brain. Writing in this weeks Science, Roman Tyzio and colleagues found that the hormone oxytocin, which is produced by a mother's brain to make her uterus contract and push out a baby, turns an excitatory nerve transmitter into an inhibitory one inside the baby's brain. This reduces the activity of the foetal neurones, cutting the brain's oxygen requirements and protecting the nervous system from injury during the birth process. The researchers studied pregnant rats and tested the response of their offspring to the transmitter chemical GABA, which usually excites foetal nerve cells. When they added oxytocin, the brain cells stopped being excited by GABA and were instead switched off by it. But when the researchers gave a drug to block oxytocin receptors the effect went away, and the nerve cells were much more susceptible to damage due to oxygen-deprivation. It's tempting to suggest that it might be possible to use this method to protect the brains of premature infants from problems such as cerebral palsy.