Up to 70 percent of mothers develop postnatal depressive mood, also known as baby blues, after their baby is born. Analyses show that this can also affect the development of the children themselves and their speech. Until now, however, it was unclear exactly how this impairment manifests itself in early language development in infants.

In a study, scientists at the Max Planck Institute for Human Cognitive and Brain Sciences in Leipzig have now investigated how well babies can distinguish speech sounds from one another depending on their mother's mood. This ability is considered an important prerequisite for the further steps towards a well-developed language. If sounds can be distinguished from one another, individual words can also be distinguished from one another. It became clear that if mothers indicate a more negative mood two months after birth, their children show on average a less mature processing of speech sounds at the age of six months. The infants found it particularly difficult to distinguish between syllable-pitches. Specifically, they showed that the development of their so-called Mismatch Response was delayed than in those whose mothers were in a more positive mood. This Mismatch Response in turn serves as a measure of how well someone can separate sounds from one another. If this development towards a pronounced mismatch reaction is delayed, this is considered an indication of an increased risk of suffering from a speech disorder later in life.

https://jamanetwork.com/journals/jamanetworkopen/fullarticle/2796564