A new study by scientists in the United States has revealed that pregnant Muslim women who fast during Ramadan are likely to have smaller babies who will be more prone to learning disabilities in adulthood.
The researchers also found that the women were 10 per cent less likely to give birth to a boy if they had fasted during Ramadan.
The trend was clearest if the fasting was done early in the women's pregnancy, and during the summer months, when long hours of daylight called for them to go longer without food.
Ramadan is the ninth month of the Islamic calendar and a time when Muslims across the world fast from dawn until sunset.
Since fasting during Ramadan is one of the five pillars of Islam and is a central part of Muslim culture, many women may fear a loss of connection with their communities or would feel guilty if they did not observe Ramadan.
The study, which used census data from the US, Iraq and Uganda, also discovered long-term effects on the adult's health and his or her future economic success.
"We generally find the largest effects on adults when Ramadan falls early in pregnancy," the Independent quoted Douglas Almond, of Columbia University, and Bhashkar Mazumder, of the Federal Research Bank of Chicago, the authors of the research, as saying.
"Rates of adult disability are roughly 20 per cent higher, with specific mental disabilities showing substantially larger effects. Importantly, we detect no corresponding outcome differences when the same design is applied to non-Muslims," they added.