Being born at below-normal weight is associated with a lower intelligence quotient (IQ) not only in childhood and young adulthood but even at the age of 50, a new study from Denmark showed.
Researchers found IQ differences between underweight and normal-weight babies remained stable into midlife.
And even within the normal birth weight range, higher weights equated with slightly higher IQ throughout life.
Birth weights of less than 2.5kg have long been linked to a variety of health problems. A normal birth weight ranges from 2.5kg to 4kg, and the average weight of infants in the study was 3.3kg.
Compared to babies born at 2.5kg or under, infants with a birth weight of 3.5kg to 4kg scored more than five points higher on IQ tests at age 28 and again at 50, the study found.
Said lead study author Trine Flensborg-Madsen of the University of Copenhagen: "There are long-term cognitive consequences of birth weight that do not diminish."
