Yom Kippur related laws:

A. Wearing leather shoes on Yom Kippur:[1]

A woman who is within thirty days of giving birth may wear leather shoes on Yom Kippur.[2] [This however only applied back then when only leather shoes were able to provide warmth, however today that there are many shoes of other material in most of the modern world, it is forbidden to wear leather shoes on Yom Kippur even in such a case.[3]]

B. Bathing on Yom Kippur:[4]

It is permitted for a woman who is a few days after birth to bathe in even hot water on Yom Kippur for the purpose of lessening her pain [although being careful not to transgress the cooking prohibition by opening the hot water valve].

Fasting on Yom Kippur:[5]

A. Within three days after birth:[6] 

A woman who is within three weekdays[7] of giving birth [i.e. Yoledes], is not to fast at all on Yom Kippur.

Says she wants to fast: If the Yoledes who is within three weekdays says she is able to fast and does not want to eat, she is to be fed even against her will. However, in such a case, she should only be fed less than the measurement of eating that has the penalty of Kareis, as explained above.

She says she needs to eat:[8] If the Yoledes who is within three weekdays says that she needs to eat, then she is to be given food in front of her and told to eat from it until she feels the danger has subsided. If less than the measurement suffices, so be it. If not, then she is to eat as much as she needs.

Does not voice an opinion:[9] If the Yoledes who is within three weekdays does not voice an opinion regarding whether she needs to eat, then she is to be given less than Shiur Kareis to eat.

Past three days but within seven:[10]

She says she needs to eat:[11] If the Yoledes is past three days from childbirth but within seven days[12] then if she says that she needs to eat, she should be fed less than the Shiur Kareis.[13] This applies even if the doctors say that it is not dangerous for her to fast.

She says she does not need to eat:[14] If the Yoledes who is past three days from childbirth but within seven days, says that she does not need to eat, then she may not be fed. [Some Poskim[15] however write that in today’s times all observant women say they do not need to eat and hence are not to be trusted. One is to rather ask a Doctor, and if a doctor is not available, one is to ask those women who have understanding in these matters.]

Does not voice an opinion:[16] If the Yoledes who is past three days from childbirth but within seven days, does not voice an opinion regarding whether she needs to eat then she may be given to eat less than Shiur Kareis, unless the doctors or her colleagues say that she does not need to eat.

Past seven days:[17]

If the Yoledes is past seven weekdays[18] from her birth, then she receives the same Halachic status as a person with a non-deadly illness. Thus, even if she says that she must eat due to the birth, it is forbidden for her to eat. If, however, she says she needs to eat because of an illness, she may be fed as is the law regarding all sick people.

How to measure the three and seven days-Are the days measured in 24 hours or in weekdays?[19]

The days are measured in weekdays and not in 24 hours. [For example; if Yom Kippur is on Wednesday night, and she gave birth on Monday night, then on Yom Kippur she is considered to be within three days from birth. If, however, she gave birth on Monday afternoon she is considered to be past three days from birth, even though 72 hours have not yet passed since she gave birth. If she gave birth on Thursday afternoon, and Yom Kippur is the following Wednesday night, then on Yom Kippur she is considered to be past seven days after birth.]

Q&A Must a woman fast if she is after a miscarriage? A woman after a miscarriage has the same status as a woman who gave birth.[20] Nevertheless, this only applies if she was pregnant for at least 40 days.[21]

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[1] Admur 614:5; Michaber 614:3; See Toras Hayoledes 55:17

[2] The reason: As they are very sensitive to cold and leather shoes keep them warm. [ibid]

^[3] Piskeiy Teshuvos 614:5; Nishmas Avraham 614:1; Nitei Gavriel 104:4 based on Mateh Efraim 614:3; Pnei Baruch 15 footnote 8; Rav Cohen

[4] Aruch Hashulchan 613:9; See regarding that one who is sick, or contains a medical condition, may bathe for medical purposes: Admur 613:7; See M”A 551:40; Elya Raba 551:35; Chayeh Adam 133:19; Mahariy Bruno 12; Shaareiy Teshuvah 551:33; Tzeida Laderech Mamar 1 3:13; Derech Hachaim 7; Kitzur SHU”A 122:12; Kaf Hachaim 551:187; Shaar Hatziyon 551:94; Piskeiy Teshuvos 551:50; Nitei Gavriel 56:20; See Encyclopedia Hilchatit Refuit Vol. 3 Erech Hirayon p. 21; See Toras Hayoledes 51:13; 55:13

[5] Admur 617:4; Toras Hayoledes 55

[6] Admur 617:4; M”B 617:10

^[7] Admur 617:5; Michaber 617:4; Terumos Hadeshen 148

Explanation: The days are calculated as weekdays and not by hours. Thus, only if she gave birth within two days before Yom Kippur does this apply. [Admur 617:5; For example; if Yom Kippur is on Wednesday night, and she gave birth on Monday night, then she does not need to fast. If, however, she gave birth on Monday afternoon she is no longer considered to be within three days of birth, even though 72 hours have not yet passed since she gave birth.]

Other opinions: Some Poskim rule the days are calculated as 24 hours each, for a total of 72 hours from the time of birth. [M”B 617:13; See Kaf Hachaim 617:22; 330:21]

[8] Admur 618:1; Vetzaruch Iyun from 617:4 in which Admur rules regarding after 3 days for her to be fed less than the measurement of Kareis even if she says that she needs to eat.

[9] Admur 618:13; Kaf Hachaim 617:19; Yechaveh Daas 6:39

Other opinions: Some Poskim rule that she is to be fed as usual, even more than the Shiur, if she does not voice an opinion. [Glosses Harav Frenkil; Shaar Hatizyon 617:12]

[10] A woman who is between 3-7 days after birth may at times be strong enough to fast, although at times the fast remains dangerous for her. This is dependent on the nature of the woman. It is for this reason that she is to be asked as to how she feels. [Aruch Hashulchan 617:4]

[11] Admur 617:4

^[12] These days are not 24-hour days, but weekdays, as explained in previous notes.

^[13] Requires Analyses: In 618:1 and 13 Admur rules that whenever she is being fed due to asking for food, then she is not fed in accordance to measurement of Kareis, but rather the food is placed in front of her and she is to be told to eat however much she feels that she needs to remove the danger, even if it is more than the measurement of Kareis. Vetzaruch Iyun why here do we feed her according to measurement?

[14] Admur 617:5

[15] Aruch Hashulchan 617:4

[16] Admur 617:5; 618:13 regarding less than Shiur

[17] Admur 617:4

[18] Meaning that seven weekdays have passed, including the day she gave birth which is counted as the first day. We do not count the days in 24 hours. [Admur 617:5]

[19] Admur 617:5; Michaber 617:4; Terumos Hadeshen 148

Other opinions: Some Poskim rule that the days are measured in 24 hours. [M”B 617:13; See Kaf Hachaim 617:22; 330:21]

[20] Biur Halacha 617 “Yoledes” in name of Sdei Chemed Mareches Yom Kippur 3:1; Piskeiy Teshuvos 617:5

[21] Sdei Chemed ibid