Summer babies are more likely to struggle with sharing, concentrating, making friends and helping than those born during winter, new research suggests.
To determine how birth season affects a child's characteristics, Queensland University of Technology researchers have matched the birth months of nearly 5000 children aged four and five with their results from a behavioural screening questionnaire. They found children born in summer months (November to January) exhibited poorer behaviour than children born in winter months (May to July).
The questionnaire assessed behaviours such as consideration of others, sharing, temperament, fidgeting, concentration and ability to make friends.
QUT associate professor of health Adrian Barnett suspects children's behavioural characteristics are linked to their exposure to vitamin D via sunlight while in utero.
"Those born in summer tend to do worse [behaviourally]. This could be because they missed the peak vitamin D time," Mr Barnett said.
"Pregnancies with summer right in the middle will likely get the highest vitamin D levels."
Birth season has previously been proved to be an environmental factor that affects a child's physical, social and psychological characteristics. Researchers believe the level of vitamin D at critical points during pregnancy and perhaps also during a child's early years plays a vital role in how the brain develops.
It has already been found that babies born in January and February have a greater chance of becoming a professional athlete.
University of Queensland professor John McGrath said low levels of vitamin D in early life have been linked to the development of schizophrenia and other brain disorders like autism and bipolar. "When you take vitamin D out of the brain's developmental soup, you expose the brain to a whole range of developmental outcomes," he said.