Leaving babies to “cry it out” does not appear to have an adverse impact on their behavioural development as a toddler, a study suggests. The topic is hotly debated among parents, with arguments for and against leaving a baby for a short time to see whether it can soothe itself before being reassured by a caregiver. But some of the research into the topic is decades old. A new study, conducted by experts at the University of Warwick, looked at 178 children and their caregivers. Parents were quizzed on their child’s frequency of crying and their use of “leaving your infant to cry out” at various stages between when the baby was born and 18 months old. The child’s behavioural development and attachment to their parent were also assessed. The study, published in the Journal of Child Psychology and Psychiatry, found that the use of the technique was rare when a baby was born, but increased over the child’s first 18 months. No adverse impacts of leaving infants to “cry it out” in the ?rst six months were found on infant–mother attachment – tested by how securely a baby is attached to their caregiver during separation and reunion episodes. Following an assessment of a cognitive test and a play session, researchers found no difference in behavioural development at 18 months between children left to cry or those soothed straight away. Meanwhile, a child’s “cry duration” was found to be lower at 18 months if parents left their infants to cry it out for a few times when they were born – and often at three months, the authors said. “Frequency of leaving infants to cry it out in the ?rst six months in infancy was not found to be associated with either adverse behavioural effects on infant development or infant–mother attachment at 18 months of age,” they wrote. But the authors cautioned that their research neither recommends leaving infant to cry out nor responding immediately. Many parents responded intuitively to their babies – going to them immediately when they cried when they were younger, but as they got older the parent waited to see whether their baby could calm themselves, the authors said. Dr Ayten Bilgin, from the Department of Psychology at the University of Warwick, said: “Only two previous studies nearly 50 or 20 years ago had investigated whether letting babies ‘cry it out’ affects babies’ development. “Our study documents contemporary parenting in the UK and the different approaches to crying used.” Professor Dieter Wolke, who led the study, added: “We have to give more credit to parents and babies. “Most parents intuitively adapt over time and are attuned to their baby’s needs, wait a bit before intervening when crying and allow their babies the opportunity to learn to self-regulate. “Most babies develop well despite their parents intervening immediately or not to crying.”