AUTISM, dyslexia and some other learning disabilities have recently been found to be more common in children who were conceived in January, February or March.

In a recent study of around 800,000 Scottish young people, research showed that these conditions were more prevalent in children conceived in the early months of the year.

Scientists from both Glasgow and Cambridge universities suggest that the findings may be linked to vitamin D deficiency in mothers.

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.”

The study, which was run in conjunction with the NHS and the Scottish Government, found that seasonal differences related not only to autism, but also to learning difficulties such as dyslexia.

Research shows that there is a 1.3% higher chance for children conceived in the first quarter to develop learning disabilities compared to those conceived between July and September.

All children in the research attended Scottish schools between 2006 and 2011 – and so were born before 2012 guidelines advising pregnant women to take vitamin D supplements to prevent other conditions, such as rickets, were drawn up.

The data came from the annual pupil census, which covers both primary and secondary levels and includes mainstream and special schools. According to the 2011 Scottish census, 99 per cent of children aged five to16 with learning disabilities are in some form of education.

The study also suggested exposure to maternal infection could be a factor, with the January-March period also linked to peaks in seasonal flu.

Most previous work has focused on the month of birth, but researchers said focusing on conception avoided variations in gestation to improve analysis.

However, 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.”

Research like this is not conclusive and it can be very confusing for parents who know that autism already runs in the family and would like to do everything they can to make sure that any children still to be born are as healthy as possible. It’s something to consider in the mix of things.