BACKGROUND Fasting during Ramadan while pregnant has been shown to have long-term negative effects on the offspring's physical and cognitive health. Even though most Muslims do not believe pregnant women are obligated to fast during Ramadan, fasting rates of up to 87% have been reported for pregnant women. No data exists to date about Ramadan adherence and behavior in Germany. METHODS The Mainz Study of Ramadan and Pregnancy surveyed pregnant Muslims and new Muslim mothers in Mainz between October 2016 and January 2017 and collected information on Ramadan adherence and behavior. We also collected data on personal characteristics and opinions, to identify determinants of fasting using statistical analysis. RESULTS We found that 43% of pregnant Muslim women fasted at least one day during Ramadan 2016. Women who fasted were significantly younger and less educated. There was no significant difference in terms of country of origin between those women who fasted and those who did not. Only 49% of women who fasted and 38% of women who did not fast discussed their Ramadan behavior with their doctor. Less than 2% of women reported being proactively approached by their doctor. CONCLUSIONS To ensure that pregnant Muslim women living in Germany can make their fasting decision based on objective information, it is necessary to raise awareness about Ramadan fasting during pregnancy among medical professionals in Germany.