Scientists have said that the condition known as “baby brain” may be caused by hormonal changes before birth, rather than the impact of bearing a child, as commonly thought. A study conducted by a team from the Francis Crick Institute on mice found that their brains began preparing for the life change of having children long before giving birth. Female mice were exposed to pups at different stages before, during, and after pregnancy, and their behavior was observed. The study revealed that mice in the late stages of pregnancy demonstrated more parental behavior, regardless of whether they were exposed to pups or not. This was attributed to the impact of the female sex hormones, oestrogen and progesterone, on neurons in the medial preoptic area (MPOA) of the brain, which is associated with parenting. Oestrogen was found to lower the baseline activity of these neurons and make them more excitable, while progesterone rewired their inputs. Previously, it was believed that hormones released after birth were responsible for mothers spending most of their time with their young. The researchers also found that virgin female rodents, who have not interacted much with pups, did not exhibit parental behavior. The study suggests that the brain undergoes preparations for parenthood during pregnancy, similar to the production of milk, which starts before giving birth. The changes associated with “baby brain” cause a change in priorities and occur earlier than the birth itself. By making the neurons insensitive to hormone changes, the researchers observed that mice no longer exhibited parental tendencies. This indicates that there is a critical period during pregnancy when these hormones take effect. Some changes lasted for at least a month after birth, and some were permanent, suggesting that pregnancy can lead to the long-term rewiring of the female brain. The researchers believe that the human brain may go through a similar rewiring during pregnancy, with hormonal changes impacting various areas of the brain that influence parental behavior. “Baby brain” is a term used to describe the deficits in memory and cognition that some women experience during pregnancy. The study’s findings, published in Science, also suggest that men may experience similar effects.
