Healthy breastfeeding women are required to fast on Tisha B’Av unless there are specific health concerns. A woman should discuss any health concerns with her physician and raise them with a halachic authority in advance of a fast.
There are different opinions regarding a Tisha B’Av nidcheh, when the fast is postponed from Shabbat to Sunday. We follow the position that a healthy breastfeeding woman should attempt to fast on a Tisha B’Av nidcheh, but that the fast should be treated with greater leniency in this case. For example, if you start to feel at all unwell during the fast, you may begin drinking and eating as necessary. Just be sure to recite havdalah first.
Ideally, you should prepare before the fast by drinking extra water for a number of days leading up to the fast. Try to rest during the fast as much as possible, staying indoors in a cool room and making arrangements for help with childcare. You may also consider pumping in advance of the fast, to have a little extra milk to use later in the day of the fast if you feel it is needed. It is important to continue to nurse or pump at the usual frequency during the fast to prevent getting a breast infection.
Please feel get back to us with any further questions.