Several medical studies have investigated the effects of Ramadan fasting. However, there is no clear answer to this question.
Some studies suggest that babies are not or little affected by fasting from their mother. Others suggest that people whose mothers fasted during pregnancy have more health problems during their lives. But it is always difficult to compare studies conducted according to different methodologies. Some of the results may depend on the health of the mother before pregnancy.
The effects on pregnancy also depend on other factors such as
the progress of your pregnancy; the period of fasting; whether Ramadan coincides with periods of heat and long days; your general health before pregnancy.
In countries where fasting lasts longer, and temperatures are very high, dehydration becomes a central concern. The countries closest to the equator tend to have shorter fasting periods.