Babies born with extremely low birthweight are not only at risk for physical problems but are also more likely to experience mental health problems later in life, according to an analysis of research conducted over nearly 30 years.
‘Our findings provide evidence that individuals born at extremely low birthweight are at higher overall risk for psychological difficulties than their normal birthweight peers. These difficulties most frequently involve attention, anxiety-related and social problems,’ said lead author Karen Mathewson, PhD, McMaster University. The study appears in the journal Psychological Bulletin, which is published by the American Psychological Association.
Preterm births have increased dramatically over the last two decades and now make up about 8% of infants born in the United States and Canada. Because of improvements in recent decades in neonatal intensive care, babies who are born at extremely low birthweight (less than 1000 gm or just over two pounds) have a greater chance of surviving than ever before.
Mathewson and her colleagues conducted meta-analyses using 41 studies that followed 2712 individuals who were extremely low birthweight babies and 11,127 who were normal birthweight babies. The studies took place over a 26-year period (1990-2016) in 12 different countries, including the United States and Canada.
Extremely low birthweight babies were found to be at increased risk for particular mental health problems, beginning in childhood and extending at least into their 30s. As children, they were significantly more likely to have attention deficit hyperactivity disorder in almost every study included in the review. Adolescents were also at greater risk for ADHD and social problems. Adults born with extremely low birthweight reported significantly higher levels of anxiety, depression and shyness, as well as significantly lower levels of social functioning.
These risks did not seem to vary according to where or when extremely low birthweight survivors were born, or whether they had significant neurosensory impairments, such as cerebral palsy or blindness. All of the studies were from developed countries from North America, Europe or Australia.
Mathewson believes these findings may stem from biological responses of the infant to difficult prenatal conditions and postnatal stresses following early birth.
‘The consistency of the findings across geographical regions suggests that these attentional, behavioural and social outcomes may be contributed to by developmentally programmed, biological factors,’ she said.
Even though the risk for mental health problems in extremely low birthweight survivors is increased compared to normal birthweight individuals, many will not develop mental disorders at all, Mathewson noted. But the effect sizes for ADHD, social problems and internalising disorders were moderate-to-large in extremely low birthweight children, and remained moderate in extremely low birthweight adolescents. (A moderate effect is generally apparent to an unaided, careful observer). Moderate effects of birthweight status suggest that group differences in the risk for these mental health problems can be significant.
The findings point to the need to continue to provide services to these individuals throughout their lives, according to Mathewson. ‘It is important that families and healthcare providers be aware of the potential for early-emerging mental health problems in extremely low birthweight survivors, and that some of these individuals may not grow out of these problems as they get older,’ she said. ‘As a result, it is essential that appropriate treatment be made available to those who require it as early in life as possible.’