The phenomenon could be caused by mothers getting more sun in pregnancy – and passing on higher quantities of vitamin D to their unborn infant.
A study of almost half a million British adults found babies born in June, July, and August were heavier at birth and taller as adults.
For the first time the research also revealed girls born in the summer started puberty later – an indication of better health in adult life.
Early puberty in girls has been linked with a higher risk of diabetes, heart disease or breast cancer.
Babies born in autumn and winter are more likely to develop food allergies – with sunlight exposure during pregnancy and vitamin D levels also thought to play a role in this.
Asthma is also more common in autumn-born children – and one theory for this is increased exposure to allergens, such as house dust mites, during the first few months of life – because of the worse weather.
But being born in summer can have drawbacks – such as an increased risk of short-sightedness.
It’s thought sunshine interferes with the delicate development of the eye – making focusing difficult and distant objects appear blurred