Nutritious food is absolutely essential during your pregnancy. Throughout your baby’s entire gestation, you should make sure you’re getting the vitamins you need and eating foods that are rich in essential minerals. Without eating properly, your baby might not be able to develop as quickly and completely as others, and he or she could suffer serious and lifelong consequences. For that reason, you can imagine the potential damage a religious fast can do to a healthy pregnancy.

Luckily for those that follow a religion that requires it, fasting during your pregnancy is not completely out of the question. No matter what type of fast you’re thinking of doing, always speak with your doctor first and find out how to make sure it has as little impact on your baby as possible. Especially during the first trimester, fasting can be safe as long as you’re feeling strong and in good health. Before your fast, your doctor will check for conditions that might complicate the effects of the fast such as gestational diabetes or the development of twins. If your doctor finds that you are well enough to carry on with a fast, you should do so. However, keep in mind that there are side effects to fasting whether or not you’re pregnant. Headaches, dizziness, and fatigue are all common during periods of fasting, so you should be careful not to faint or fall over. If you feel especially weak, contact your doctor immediately.

Also, look for ways around a typical fast. Depending on the religion or custom you’re following, there are sometimes exceptions to the rule. You might be able to eat fruits and vegetables during your fast, or even split the fasting time with a partner. Your partner could fast for part of the designated day, and you could fast for the other. Some traditions also make exceptions for pregnant women and allow them to fast at a later date. If you decide that you’ll fast on your own, rest as much as possible. The lack of nutrients will be fatiguing, especially when you’re carrying around the extra weight of your baby. Avoid excessive heat, and stay well hydrated.

If you can’t bring yourself to hold off on your fast until after pregnancy, there are ways you can have a safe and successful fasting period by clearing it with your doctor and making it as safe and ineffectual as possible.

Source: Bhashkar Mazumder et al: The Effect of Maternal Fasting During Pregnancy. Health Capital and the Prenatal Environment Volume 2007 Issue 22 April 2011