Shift.ms says that women whose pregnancies span the summer months absorb greater vitamin D from a stronger sun - which research shows has a positive impact on immune system development, Daily Mail reports.

Affecting nearly 100,000 people in the UK, MS is the most common disabling neurological condition for young adults today and Shift.ms is campaigning for greater awareness of the crippling nerve condition.

Multiple Sclerosis usually strikes people in their 20s and 30s and affects 2.5million people around the world, including 85,000 Britons.

It can cause blindness and paralysis, but current drugs are not suitable for all and there is no cure.

Multiple sclerosis occurs when ‘friendly fire' from the body's immune system, destroys myelin, the fatty protective sheath around nerve fibres in the brain and spinal cord, disrupting the transmission of signals vital to everything from seeing and walking to thinking and bladder control.

The research shows white blood cells called T cells to be pivotal to the process.

Professor Gavin Giovannoni, Chair of Neurology at Barts Health NHS Trust, said: 'This supports my current recommendation that all woman should be taking physiological doses of vitamin D supplements during pregnancy.

It is already known that MS cases are higher in countries like Britain which are further away from the equator with relatively low sunlight levels.

Diabetes, asthma and life-threatening heart disease in babies are also linked to low levels of vitamin D in early life.