Babies conceived between March and January more likely to have learning problems, scientists find
Babies conceived between March and January are more likely to have learning difficulties because their mothers did not get enough vitamin D in pregnancy, a new study suggests.
Learning problems, such as dyslexia, reading problems and ADHD, are more prevalent in children born in the winter, suggesting that mothers were not getting enough of the sunshine vitamin during their first trimester.
Researchers said it was possible that modern indoors lifestyles contributed to the rise in learning difficulties which have been steadily growing for decades, although diagnosis, awareness and recording have also improved in the same period.
Last month, Public Health England recommended that adults should take 10 micrograms supplements of vitamin D during the British autumn and winter because indoor life and gloomy weather was leading to widespread deficiencies.
The study of more than 800,000 children by the Universities of Glasgow and Cambridge, the NHS and the Scottish Government, found 8.9 per cent of children conceived in the first quarter of the year had learning disabilities compared to 7.6 per cent of those conceived between July and September.
They believe that 11 per cent of all learning difficulties could be prevented if expectant mothers were to follow NHS guidance on taking vitamin D supplements. Around 700,000 babies are born in Britain each year, which suggests more than 2,000 children a year end up with learning difficulties needlessly.
Professor Gordon Smith, department head of obstetrics and gynaecology at Cambridge, said: "If vitamin D levels do indeed explain the seasonal fluctuations observed in this study, we would hope that widespread compliance with the advice would lead to loss of this variation, and would have a downward effect on overall rates of special educational needs.
"Although the current study did not directly measure vitamin D, it remains perhaps the most plausible explanation for the trend.
"Hence, these findings underline the importance of health professionals recommending vitamin D, and the importance of women complying with the treatment to optimise their chances of a healthy child."
The children in the research were born before 2012 guidelines advising all pregnant women to take 10 microgram vitamin D supplements to prevent other conditions, such as rickets. But there are fears that women are still not following the advice.
Professor Jill Pell, director of Glasgow's Institute of Health and Wellbeing, added: "It is important that pregnant women follow the advice to take vitamin D supplements and also that they start supplements as early in pregnancy as possible - ideally when they are trying to get pregnant.
Asked whether modern indoor lifestyle contributed to the rise in learning difficulties, Prof Pell added: “The suggestion is possible but reduced exposure to sunlight is likely to have occurred over decades rather than a few years and other things will also have changed over that time such as awareness, diagnosis and recording.”
The research, published in the American Journal of Epidemiology, looked at health and education data collected from 801,592 children who attended Scottish schools between 2006 and 2011.