The coronavirus pandemic has made babies worse at communicating.
Young babies usually fixate on the eyes of their carers while older tots focus on the mouth as they learn basic skills of communication.
However, lockdown and mask-wearing means has limited the amount of access babies have to important visual cues and has stunted their development.
The research team at the University of Medicine and Health Sciences in Dublin studied 12-month-old babies born in the early months of the pandemic and found that just 77 per cent could express one definite word - compared to 89 per cent in normal circumstances.
The experts said: "Pandemic-associated social isolation appears to have impacted social communication skills in babies born during the pandemic."
The study also stressed that the skills are likely to improve as babies return to society with the health crisis easing.
The researchers added: "Babies are silent and inquisitive by nature and it is very likely with societal re-emergence and increase in social circles their social communication skills will improve."