Vaginal birth triggers the expression of an essential brain-boosting protein in babies that improves brain development and function later in adulthood, a new study reveals.

However, the brains of babies delivered by cesarean section may have impaired expression of the brain-boosting mitochondrial uncoupling protein 2 (UCP2), according to the latest findings published in the journal PLoS ONE.

Yale researchers studied mice to examine the effect of natural and surgical deliveries on the expression of UCP2 protein in offspring. 

Scientists said that UCP2 is important for the proper development of the neurons and circuits located in the hippocampus, an essential brain region that is responsible for short-term and long-term memory and spatial orientation.

The protein is also involved in the cellular metabolism of fat, which is a main component of breast milk, suggesting that triggering of UCP2 expression by natural birth may help newborns transition to breast feeding.

While natural birth appeared to trigger UCP2 expression in hippocampal neurons in mice, the expression was diminished in the brains of mice born by C-section.

When researchers turned off UCP2 gene or inhibited its function in adult mice, the rodents performed and behaved differently in laboratory mazes compared to normal functioning mice. The experimental mice explored less of the maze, moved more slowly and stayed closer to the walls compared to mice with normal levels of UCP2.

"These results reveal a potentially critical role of UCP2 in the proper development of brain circuits and related behaviors," lead researcher Tamas Horvath, PhD, said in a statement.

The authors wrote that long lasting effects of reduced UCP2 activity, which can be caused by C-section, in early development may affect many complex behaviors in adulthood.

"The increasing prevalence of C-sections driven by convenience rather than medical necessity may have a previously unsuspected lasting effect on brain development and function in humans as well," Horvath warned.

Researchers said that the next step is to determine whether UCP2 has the same effects in humans as in mice.  Researchers would also like to see if the same effects of natural birth and C-section delivery apply to other animals such as dogs or pigs.