[10] In general, a pregnant woman refers to one who is noticeably pregnant (c. three months pregnant). However, in the present case, the Aĥaronim stated that since a woman is in greater pain and at higher risk of miscarriage specifically during the first few months of pregnancy, a woman who knows with certainty that she is pregnant, based on a test or the like, is exempt from fasting. However, mb 550:3 and sht ad loc. 2 state that one may rely on this approach and be lenient before the fortieth day of pregnancy only if she is in great pain (as then she is considered sick). In my humble opinion, though, this ruling was based on technology available then, which could not produce certainty of early-stage pregnancy. However, if one knows with certainty that she is pregnant, the danger of miscarriage already exists, and it is clear that her aches are a result of her pregnancy. Therefore, like all pregnant women, she need not fast. Mikra’ei Kodesh (Harari) ch. 1 n. 10 states that R. Mordechai Eliyahu ruled likewise.

Rabbeinu Yeruĥam, Radbaz, and other poskim write that pregnant and nursing women may not fast on the minor fast days. Rema writes that such women have a custom to be stringent and fast. The Aĥaronim (Ĥayei Adam 133:6, ahs 550:1) divide pregnant and nursing women into three categories: healthy women have the custom to be stringent; those who experience some pain when fasting are exempt from the custom to be stringent, but are not prohibited from fasting; and those who suffer greatly may not be stringent. Nowadays, the prevalent ruling for Ashkenazic women is to refrain from fasting. See Piskei Teshuvot 550:1, which cites extremely lenient views, stating that all women who might give birth are exempt from these fasts, so that they have strength to give birth. Piskei Teshuvot also cites the view that such women should “redeem” the fast by giving charity. Most poskim do not accept this opinion, but one may use it as an additional reason to rule leniently in cases of uncertainty.

[11] The following authorities rule leniently: Maharsham, Da’at Torah 550; Yeĥaveh Da’at 1:35. See the previous note. According to the straightforward interpretation, however, only nursing women are exempt; this is the view of most poskim. R. Mordechai Eliyahu concurs in Hilkhot Ĥagim 24:35. For a summary of the various opinions, see Mikra’ei Kodesh (Harari) 1:4.