Halacha

הלכה א
כָּל יוֹלֶדֶת טְמֵאָה כְּנִדָּה וְאַף עַל פִּי שֶׁלֹּא רָאֲתָה דָּם. וְאֶחָד הַיּוֹלֶדֶת חַי אוֹ מֵת אוֹ אֲפִלּוּ נֵפֶל. אִם זָכָר יוֹשֶׁבֶת לְזָכָר וְאִם נְקֵבָה יוֹשֶׁבֶת לִנְקֵבָה וְהוּא שֶׁתִּגָּמֵר צוּרָתוֹ. וְאֵין צוּרַת הַוָּלָד נִגְמֶרֶת לְפָחוֹת מֵאַרְבָּעִים יוֹם אֶחָד הַזָּכָר וְאֶחָד הַנְּקֵבָה:
כסף משנה
1.
Every woman who gives birth is impure like a niddah, even if she did not suffer uterine bleeding.1The Kessef Mishneh notes that in Chapter 5, Halachah 13, the Rambam rules that when a woman discharges a piece of flesh from the vagina, it must be accompanied by bleeding. For discharging that piece of flesh is not considered as giving birth. With regard to giving birth (or miscarrying), however, the Torah deems a woman is impure, whether or not the birth is accompanied by bleeding. [This applies whether] a woman gives birth to a living child or one which is still born, and even is she miscarries [and discharges a fetus]. If [the fetus is] male, she remains impure [for seven days as is required after giving birth to] a male.2See Chapter 4, Halachah 2. If it is female, she remains impure [for fourteen days as is required after giving birth to] a female.
[The above applies,] provided the form [of the fetus] is complete. And the form of a fetus will never become complete in less than forty days. [This applies] to both a male and a female.

הלכה ב
וְהַמַּפֶּלֶת בְּתוֹךְ אַרְבָּעִים יוֹם אֵינָהּ טְמֵאָה לֵדָה אֲפִלּוּ בְּיוֹם אַרְבָּעִים. הִפִּילָה בְּיוֹם אַרְבָּעִים וְאֶחָד מֵאַחַר הַתַּשְׁמִישׁ הֲרֵי זוֹ סְפֵק יוֹלֶדֶת וְתֵשֵׁב לְזָכָר וְלִנְקֵבָה וּלְנִדָּה. הָיְתָה צוּרַת הָאָדָם דַּקָּה בְּיוֹתֵר וְאֵינָהּ נִכֶּרֶת בַּעֲלִיל הֲרֵי זוֹ תֵּשֵׁב לְזָכָר וְלִנְקֵבָה וְזֶהוּ הַנִּקְרָא שַׁפִּיר מְרֻקָּם:
כסף משנה
2.
If a woman miscarries within forty days, she is not impure because of birth.3A miscarriage is usually accompanied by uterine bleeding. Thus the woman will become impure (as a niddah or as a zavah). However, the unique laws that apply to childbirth do not apply to her.
Even if she had conceived previously, until she reaches the fortieth day, the embryo is not given the halachic status of a fetus and none of the laws applying to childbirth apply.
[This applies] even on the fortieth day.
If a woman miscarried on the forty-first day after relations,4I.e., the forty-first day after she immersed herself in the mikveh and engaged in relations that night. there is a doubt whether she is considered as having miscarried.5I.e., it is possible that she conceived after engaging in relations that night, but we are not certain. Hence, her status is doubtful. [Hence,] she is governed by the laws that apply to the birth of a male and a female and those applying to a niddah.6Since it is possible that the fetus was male, it is possible that it was female, and it is possible that it was not considered a fetus in the halachic sense at all, the woman must take all these possibilities into consideration. See Halachah 21 which defines the laws incumbent on a woman in this situation. If the human form could be barely detected in the fetus without it being clear and obvious, she is governed by the laws that apply to the birth of a male and a female.7In this instance, it is clear that the embryo had developed into a fetus. Hence the laws that apply to ordinary uterine bleeding need not be considered. Nevertheless, since we are uncertain whether the fetus is male or female, the woman must take both of these factors into consideration. See Halachah 20 which describes the laws that a woman must follow in such a situation. This is called a developed8Rekem, the root of the term merukam, means "embroidered." Implied is that the form of the embryo is beginning to take shape. embryo.

הלכה ג
אֵי זֶה הוּא שַׁפִּיר מְרֻקָּם. תְּחִלַּת בְּרִיָּתוֹ שֶׁל אָדָם גּוּפוֹ כַּעֲדָשָׁה. שְׁתֵּי עֵינָיו כִּשְׁתֵּי טִפֵּי זְבוּב מְרֻחָקוֹת זוֹ מִזּוֹ. שְׁנֵי חֳטָמָיו כִּשְׁתֵּי טִפֵּי זְבוּב מְקֹרָבוֹת זֶה לָזֶה. פִּיו פָּתוּחַ כְּחוּט הַשַּׂעֲרָה. וְחִתּוּךְ יָדַיִם וְרַגְלַיִם אֵין לוֹ. נִתְבָּאֲרָה צוּרָתוֹ יֶתֶר מִזֶּה וַעֲדַיִן אֵינוֹ נִכָּר בֵּין זָכָר לִנְקֵבָה אֵין בּוֹדְקִין אוֹתוֹ בְּמַיִם אֶלָּא בְּשֶׁמֶן שֶׁהַשֶּׁמֶן מְצַחְצְחוֹ. וּמֵבִיא קֵיסָם שֶׁרֹאשׁוֹ חָלָק וּמְנַעְנֵעַ בְּאוֹתוֹ מָקוֹם מִלְּמַעְלָה לְמַטָּה אִם מְסַכְסֵךְ בְּיָדוּעַ שֶׁהוּא זָכָר. וְאִם רָאָה אוֹתוֹ מָקוֹם כִּשְׂעוֹרָה סְדוּקָה הֲרֵי זוֹ נְקֵבָה וְאֵינָהּ צְרִיכָה בְּדִיקָה. וְכָל אֵלּוּ הָרְקִימוֹת שֶׁל נְפָלִים אֵין נוֹתְנִין לָהֶן יְמֵי טֹהַר עַד שֶׁיַּשְׂעִיר הַוָּלָד:
כסף משנה
3.
What is meant by a developed embryo? At the beginning of the formation of the human body, it is the size of a lentil. His two eyes are like the two eyes9Alternatively, as two drops of a fly's discharge. of a fly, [slightly] separate from each other. His two nostrils are like two eyes of a fly that are close to each other. Its mouth is a hairsbreadth open and its hands and feet are not distinct.
If its form becomes more defined than this, but it still cannot be distinguished as either male or female, we do not check it in water, but in oil. For the oil will burnish it. One should bring a wood chip with a smooth edge and use it to probe the genital area [of the fetus] from above downward. If there is an obstruction, it can be determined as male.10For ultimately, the male organ will grow there. If the genital area appears like a split barley corn, it is a female and need not be checked. A woman is not granted the leniency of "the blood of purity" for such underdeveloped embryos; the fetus must have hair on its head.

הלכה ד
הִפִּילָה חֲתִיכָה לְבָנָה אִם נִקְרְעָה וְנִמְצָא בָּהּ עֶצֶם הֲרֵי זוֹ טְמֵאָה לֵדָה. הִפִּילָה שַׁפִּיר מָלֵא מַיִם מָלֵא דָּם מָלֵא גִּנּוּנִים מָלֵא בָּשָׂר הוֹאִיל וְאֵינוֹ מְרֻקָּם אֵינָהּ חוֹשֶׁשֶׁת לְוָלָד:
כסף משנה
4.
When a woman discharges a white mass and when cut open a bone is found within, she is impure, because of birth.11For we assume that the mass was a dead fetus. The fact that it contains a bone indicates that it had developed sufficiently to acquire the features mentioned in the previous halachah. Obviously, certain factors had caused the fetus to be crushed and the features obliterated. If she discharges an embryo filled with water, blood, worms,12Our translation is based on the Rambam's Commentary to the Mishnah (Niddah 3:3) which interprets the Hebrew as referring to "flesh that appears to be cut in the form of worms." or flesh, since it is not developed,13I.e., developed to the point it possesses the features mentioned in the previous halachah. the woman need not suspect [that she is impure] because of birth.14Moreover, if there is no apparent blood on the discharge, she is not impure as a niddah (the Rambam's Commentary to the Mishnah, loc. cit.; see also Chapter 5, Halachah 13).
The Shulchan Aruch (Yoreh De'ah 194:3) states that in the present age, we follow the approach of the Rashba who rules that we are not knowledgeable enough to make the fine distinctions necessary to define when an embryo is developed or not. Hence, a woman should always consider herself impure because of birth.

הלכה ה
יוֹצֵא דֹּפֶן אֵין אִמּוֹ טְמֵאָה לֵדָה וְאֵין לָהּ יְמֵי טֻמְאָה וִימֵי טָהֳרָה שֶׁנֶּאֱמַר (ויקרא יב ב) "אִשָּׁה כִּי תַזְרִיעַ וְיָלְדָה זָכָר" עַד שֶׁתֵּלֵד מִמָּקוֹם שֶׁמַּזְרַעַת. הַמַּקְשָׁה וְיָלְדָה וָלָד דֶּרֶךְ הַדֹּפֶן הֲרֵי דַּם הַקֹּשִׁי הַבָּא דֶּרֶךְ הָרֶחֶם זִיבוּת אוֹ נִדָּה וְדָם הַיּוֹצֵא דֶּרֶךְ הַדֹּפֶן טָמֵא. וְאִם לֹא יָצָא דָּם דֶּרֶךְ הָרֶחֶם הֲרֵי הָאִשָּׁה טְהוֹרָה. אַף עַל פִּי שֶׁהַדָּם שֶׁיָּצָא מִדָּפְנָהּ טָמֵא. שֶׁאֵין הָאִשָּׁה טְמֵאָה עַד שֶׁיֵּצֵא מַדְוֶהָ דֶּרֶךְ עֶרְוָתָהּ:
כסף משנה
5.
When a child is born through Cesarean section, the mother is not impure because of birth. She [need] not [observe] the days of impurity, [nor is she granted] days of purity. [This is derived from Leviticus 12:2]: "When a woman will conceive and give birth to a male...." [The laws of that passage apply] only when she gives birth from the place she conceives.
When a woman has difficulties in giving birth and [ultimately,] gives birth through Cesarean section, the blood from the birth throes which emerges from the womb is considered as the blood of zivah or the blood of niddah.15Depending on the day of her cycle on which the blood emerged.
Although the Torah considered the blood that emerges during birth pure (Chapter 6, Halachah 1), that apples when the woman gives birth in an ordinary manner, and not when she gives birth by Cesarean section (Rashi, Niddah 41a).
The blood that emerges from the operation is itself impure.16The blood itself is impure, because the uterus itself is impure and it conveys impurity on the blood. Therefore anyone who touches the blood is impure until the evening. The blood does not, however, convey impurity on the woman unless it comes into contact with her after it emerges from her body. If no blood emerged from the womb, the woman is pure. Although the blood that emerges from the operation is impure, the woman does not become impure unless she suffers bleeding from her vagina.17Niddah, loc. cit., derives this concept from the exegesis of Leviticus 20:18.

הלכה ו
נֶחְתַּךְ הַוָּלָד בְּמֵעֶיהָ וְיָצָא אֵיבָר אֵיבָר. בֵּין שֶׁיָּצָא עַל סֵדֶר הָאֵיבָרִים כְּגוֹן שֶׁיָּצְאָה הָרֶגֶל וְאַחֲרֶיהָ הַשּׁוֹק וְאַחֲרֶיהָ הַיָּרֵךְ. בֵּין שֶׁיָּצָא שֶׁלֹּא עַל הַסֵּדֶר אֵינָהּ טְמֵאָה לֵדָה עַד שֶׁיֵּצֵא רֻבּוֹ. וְאִם יָצָא רֹאשׁוֹ כֻּלּוֹ כְּאֶחָד הֲרֵי זֶה כְּרֻבּוֹ. וְאִם לֹא נֶחְתַּךְ וְיָצָא כְּדַרְכּוֹ מִשֶּׁתֵּצֵא רֹב פַּדַּחְתּוֹ הֲרֵי זֶה כְּיָלוּד אַף עַל פִּי שֶׁנֶּחְתַּךְ אַחַר כָּךְ:
כסף משנה
6.
When a fetus is cut up inside a woman's womb,18I.e., the woman was unable to birth the baby and the doctors saw that to save the woman's life, the fetus would have to be killed and taken out limb by limb. whether it emerged according to the order of the limbs, e.g., first a foot emerged, then a calf, and then a thigh, or it emerged in an abnormal order, the woman is not considered impure until the majority of the body emerges.19I.e., the point brought out by this halachah is not whether the woman becomes impure, but when the impurity takes effect. The Siftei Cohen 194:9 states that the law stated by the Rambam applies according to Scriptural Law. According to Rabbinic decree, she is impure as soon as one limb emerges. If its entire head comes out intact, it is as if the majority [of the body] emerged.20Although the Mishnah (Niddah 3:5) uses the phrase "the majority of the head," the Rambam maintains that the entire head must emerge for this law to apply. See the Maggid Mishneh and Kessef Mishneh. If it was not cut up and it emerged in the ordinary manner, it is considered as having been born when its forehead emerges, even though it was cut up afterwards.21I.e., complications arose and it was necessary to cut up the fetus to remove it from the womb entirely.

הלכה ז
הוֹצִיא הָעֻבָּר אֶת יָדוֹ וְהֶחֱזִירָהּ אִמּוֹ טְמֵאָה לֵדָה מִדִּבְרֵי סוֹפְרִים. וְאֵין לָהּ יְמֵי טֹהַר עַד שֶׁיֵּצֵא הַוָּלָד כֻּלּוֹ אוֹ רֻבּוֹ כְּמוֹ שֶׁאָמַרְנוּ:
כסף משנה
7.
If a fetus sticks out its hand22The Maggid Mishneh questions whether the same laws apply with regard to a foot. The Tur states that they do, while the Shulchan Aruch (Yoreh De'ah 194:11) quotes the Rambam's ruling verbatim. [from the womb] and then returns it, its mother is impure due to birth as a result of Rabbinic decree.23Although Genesis 38:28 states: "And when she was giving birth, he stuck out a hand," Niddah 28a rules that this should not be interpreted as an implication that sticking out a hand is considered as giving birth. Instead, according to Scriptural Law, the woman does not become impure until the majority of the body of the fetus emerges. The woman does not receive "days of purity" until the entire fetus - or [at least] the majority - emerges as we stated.24I.e., as implied by the previous halachah.

הלכה ח
הַמַּפֶּלֶת כְּמִין בְּהֵמָה חַיָּה אוֹ עוֹף אִם הָיוּ פָּנָיו כִּפְנֵי אָדָם הֲרֵי זֶה וָלָד. אִם זָכָר תֵּשֵׁב לְזָכָר וְאִם נְקֵבָה תֵּשֵׁב לִנְקֵבָה. וְאִם אֵינוֹ נִכָּר בֵּין זָכָר לִנְקֵבָה תֵּשֵׁב לְזָכָר וְלִנְקֵבָה אַף עַל פִּי שֶׁשְּׁאָר הַגּוּף דּוֹמֶה לִבְהֵמָה אוֹ לְחַיָּה אוֹ לְעוֹף. וְאִם אֵין פָּנָיו כְּצוּרַת פְּנֵי הָאָדָם אַף עַל פִּי שֶׁשְּׁאָר הַגּוּף גּוּף אָדָם שָׁלֵם וְיָדָיו וְרַגְלָיו יְדֵי וְרַגְלֵי אָדָם וַהֲרֵי הוּא זָכָר אוֹ נְקֵבָה אֵינוֹ וָלָד וְאֵין אִמּוֹ טְמֵאָה לֵדָה:
כסף משנה
8.
[The following laws apply when] a woman miscarries and discharges something resembling an animal, beast, or fowl.25In his Commentary to the Mishnah (Niddah 3:2), the Rambam explains that although it is abnormal for a woman to discharge a fetus with such an appearance, there are exceptional situations from time to time. These and the forms mentioned in the following halachot are definite possibilities. If its face resembles that of a human,26As defined in the following halachah. it is considered as a birth even though the remainder of the body resembles an animal, beast, or fowl. If it is male, she is governed by the laws that apply to the birth of a male. If it is female, she is governed by the laws that apply to the birth of a female. If it cannot be determined whether it is male or female, she is governed by the laws that apply to the birth of a male and a female.
If its face does not resemble that of a human, it is not considered as a fetus and its mother is not impure due to birth.27The Maggid Mishneh states that this law also applies in the present era, as indicated by Chapter 11, Halachah 12. In his Kessef Mishneh, Rav Yosef Caro differs, citing the Ra'avad and the Ramban and explaining that the Rabbis of the present era did not feel that they were expert enough to determine if the face of a fetus resembled that of a man or not. Hence they ruled that woman is impure. In his Shulchan Aruch (Yoreh De'ah 194:3), he follows this approach.
Note also Halachah 17 which states that if the discharge of such a fetus is accompanied by bleeding, the woman is impure even if the fetus does not resemble a human.
[This applies] even though the remainder of the body resembles that of a human, its hands and feet resemble those of a human, and it is male or female.

הלכה ט
אֵי זוֹ הִיא צוּרַת פְּנֵי הָאָדָם. שֶׁיִּהְיֶה הַמֶּצַח וְהַגְּבִינִין וְהָעֵינַיִם וְהַלְּסָתוֹת וְגַבּוֹת הַזָּקָן כְּצוּרַת הָאָדָם. אֲבָל הַפֶּה וְהָאָזְנַיִם וְהָאַף אַף עַל פִּי שֶׁהֵן כְּשֶׁל בְּהֵמָה וְחַיָּה הֲרֵי זֶה וָלָד:
כסף משנה
9.
What is meant by the human form of a face? That the forehead, eyebrows, eyes, cheeks, and the contour of the jaw share the human form. Even if the mouth, the ears, and the nose resemble that of an animal or a beast, [the fetus] is considered as a birth.

הלכה י
הַמַּפֶּלֶת דְּמוּת נָחָשׁ אִמּוֹ טְמֵאָה לֵדָה מִפְּנֵי שֶׁגַּלְגַּל עֵינָיו עָגל כְּשֶׁל אָדָם. הַמַּפֶּלֶת דְּמוּת אָדָם שֶׁיֵּשׁ לוֹ כְּנָפַיִם שֶׁל בָּשָׂר אִמּוֹ טְמֵאָה לֵדָה. נִבְרָא בְּעַיִן אַחַת וְיָרֵךְ אַחַת אִם הָיוּ מִן הַצַּד הֲרֵי הוּא כַּחֲצִי אָדָם וְאִמּוֹ טְמֵאָה לֵדָה. וְאִם הָיוּ בָּאֶמְצַע אִמּוֹ טְהוֹרָה שֶׁהֲרֵי זוֹ בְּרִיָּה אַחֶרֶת:
כסף משנה
10.
When a woman miscarries and discharges something resembling a snake, the mother is impure due to birth.28The Ra'avad questions the Rambam's ruling, noting that in the previous two halachot, he stated that for a fetus to be considered as having a human form, it must have the majority of a human facial form intact, not merely the eyes. The Kessef Mishneh supports the Rambam's ruling, explaining that the eye of a snake resembles that of a human much more closely than that of other animals. Hence, there is room for the Rambam's ruling. [The rationale is that] the form of its eye is round like that of a human. When a woman miscarries and discharges a human form that has wings of flesh, the mother is impure due to birth.
[The following rules apply when a fetus] is created with one eye and one thigh. If they are on the side, it is considered as half a human and the mother is impure due to birth. If they are in the center, the mother is pure, because this is another creature.

הלכה יא
נִבְרָא וֵשֶׁט שֶׁלּוֹ אָטוּם אוֹ שֶׁהָיָה חָסֵר מִטִּבּוּרוֹ וּלְמַטָּה וַהֲרֵי הוּא אָטוּם. אוֹ שֶׁהָיְתָה גֻּלְגָּלְתּוֹ אֲטוּמָה. אוֹ שֶׁהָיוּ פָּנָיו טוּחוֹת וְאֵין בָּהֶן הֶכֵּר פָּנִים. אוֹ שֶׁיֵּשׁ לוֹ שְׁנֵי גַּבִּין וּשְׁתֵּי שְׁדֵרוֹת. אוֹ שֶׁהִפִּילָה בְּרִיַּת רֹאשׁ שֶׁאֵינוֹ חָתוּךְ. אוֹ יָד שֶׁאֵינוֹ חָתוּךְ. כָּל נֵפֶל מֵאֵלּוּ אֵינוֹ וָלָד וְאֵין אִמּוֹ טְמֵאָה לֵדָה. אֲבָל אִם הִפִּילָה יָד חֲתוּכָה וְרֶגֶל חֲתוּכָה הֲרֵי חֶזְקָתָהּ מִוָּלָד שָׁלֵם וּמִצְטָרְפִין לְרֹב אֵיבָרָיו:
כסף משנה
11.
[The following laws apply when a fetus] is created with its windpipe closed, its body lacking [form] from the navel downward, but instead is a mass of flesh, its skull being merely a mass of flesh, its face was amorphous and its features could not be distinguished, it has two backs and two backbones, the contours of the head of the fetus she discharged could not be distinguished, or the contours of its hand could not be distinguished, the mother is not impure due to birth.29This ruling is based on Niddah 23b which states that any fetus that is created in a manner that is not fit for its soul to be created (i.e., it is not viable) does not cause the mother to be impure due to birth. Since a fetus with these defects would not live, the mother is not impure. See the Kessef Mishneh which questions the details of certain of the examples cited by the Rambam.
If, however, she miscarried and discharged a hand or a foot that was cut off, we operate under the assumption that it came from a complete fetus and it is included in the sum of the majority of its limbs.30As stated in Halachah 6, when the majority of the limbs of a fetus emerge, the mother is considered as impure due to birth. The present halachah is stating that if previously many of the limbs of a fetus emerged and then the mother discharged this cut off hand or foot, it is not considered as part of a separate fetus, but instead, part of the fetus that already emerged. Hence, if together with the limbs that previously emerged, it equals the majority of the fetus, the woman is impure (Maggid Mishneh).
From Rabbi Akiva Eiger's interpretation of Niddah 28a, the source for this halachah, the following explanation can be given. When a woman discharges a cut off hand or foot, even if we have not seen the remainder of the fetus, we assume that she discharged them already. Hence, she is considered impure. We do not suspect that maybe the fetus she discharged was not viable.

הלכה יב
פְּעָמִים יִקְפֶּה מִשְּׁאָר הַדָּמִים שֶׁנּוֹצַר מֵהֶם הָאָדָם חֲתִיכָה כְּמוֹ לְשׁוֹן הַשּׁוֹר וְתִהְיֶה כְּרוּכָה עַל מִקְצָת הַוָּלָד וְהִיא הַנִּקְרֵאת סַנְדָּל. וּלְעוֹלָם לֹא יֵעָשֶׂה סַנְדָּל זֶה אֶלָּא עִם וָלָד. אֲבָל חֲתִיכָה שֶׁנּוֹצְרָה לְבַדָּהּ בְּלֹא וָלָד אֵינָהּ נִקְרֵאת סַנְדָּל. וְרֹב הָעֵבָּרִים לֹא יִהְיֶה עִמָּהֶם סַנְדָּל. וּפְעָמִים יַכֶּה הַמְעֻבֶּרֶת דָּבָר עַל בִּטְנָהּ וְיִפָּסֵד הָעֻבָּר וְיֵעָשֶׂה כְּסַנְדָּל זֶה. וּפְעָמִים יִשָּׁאֵר בּוֹ הֶכֵּר פָּנִים וּפְעָמִים יִיבַשׁ הַוָּלָד וְיִשְׁתַּנֶּה וְיִקְפְּאוּ עָלָיו הַדָּמִים עַד שֶׁלֹּא יִשָּׁאֵר בּוֹ הֶכֵּר פָּנִים. לְפִיכָךְ הַמַּפֶּלֶת זָכָר וְסַנְדָּל עִמּוֹ אַף עַל פִּי שֶׁאֵין הֶכֵּר פָּנִים לַסַּנְדָּל הֲרֵי זוֹ תֵּשֵׁב לְזָכָר וְלִנְקֵבָה שֶׁמָּא סַנְדָּל זֶה נְקֵבָה הָיָה. וְחֻמְרָא הֶחְמִירוּ בּוֹ לְטַמְּאָהּ בּוֹ מִשּׁוּם וָלָד אַף עַל פִּי שֶׁאֵין בּוֹ צוּרַת פָּנִים הוֹאִיל וְהִיא טְמֵאָה לֵדָה מִפְּנֵי הַוָּלָד שֶׁעִמּוֹ:
כסף משנה
12.
There are times when from the remainder of the blood from which a fetus is formed will coagulate and form a mass that resembles the tongue of an ox. It is wound around a portion of the fetus and is called a sandal. A sandal will never be formed without a fetus. If a similar mass is formed without a fetus, it is not called a sandal. Most fetuses will not have a sandal with them.
There are times when a pregnant woman will receive a blow on her stomach and the fetus will be damaged and will become like this sandal. There are time when the [resulting sandal] will retain its facial features and there are times when the fetus will dry up and change its appearance and blood from elsewhere will coagulate upon it to the extent that its facial features cannot be recognized.
Accordingly, when a woman miscarries and discharges a male fetus together with a sandal, she is governed by the laws that apply to the birth of a male and a female. For perhaps this sandal was a female fetus. [The Sages] ruled stringency and considered her impure due to a [female] fetus even though it did not possess any facial features. [The rationale is that] she is impure due to birth regardless because of the fetus [discharged] with it.

הלכה יג
הַחוֹתֶלֶת הֶעָבָה שֶׁהִיא כְּמוֹ חֵמֶת שֶׁבְּתוֹכָהּ נוֹצָר הַוָּלָד וְהִיא מַקֶּפֶת אוֹתוֹ וְאֶת הַסַּנְדָּל אִם הָיָה עִמּוֹ סַנְדָּל וּכְשֶׁיַּגִּיעַ זְמַנּוֹ לָצֵאת קוֹרֵעַ אוֹתָהּ וְיוֹצֵא הִיא הַנִּקְרֵאת שִׁלְיָא. וּתְחִלַּת בְּרִיָּתָהּ דּוֹמָה לְחוּט שֶׁל עֵרֶב וַחֲלוּלָה כַּחֲצוֹצֶרֶת וְעָבָה כְּקֻרְקְבָן הַתַּרְנְגוֹלִים. וְאֵין שִׁלְיָא פְּחוּתָה מִטֶּפַח:
כסף משנה
13.
The thick membrane that is like a goatskin in which the fetus is formed and which surrounds the fetus and the sandal - if there is a sandal with it - is called the placenta. When the time comes for the fetus to emerge, it tears it and emerges. At the beginning of its creation, it resembles a thread of the woof that is hollow like a trumpet and thick like the craw of a chicken. A placenta must be at least a handbreadth in size.31Implied is a leniency. If a woman discharges something resembling a placenta, but which is smaller than a handbreadth, she is not impure due to birth. The Maggid Mishneh quotes Ramban and Rashba who rule that in the present age, we are stringent and rule her impure even if it is smaller than a handbreadth lest an error be made.

הלכה יד
הַמַּפֶּלֶת שִׁלְיָא תֵּשֵׁב לְזָכָר וְלִנְקֵבָה. לֹא שֶׁהַשִּׁלְיָא וָלָד אֶלָּא שֶׁאֵין שִׁלְיָא בְּלֹא וָלָד. הִפִּילָה נֵפֶל וְאַחַר כָּךְ הִפִּילָה שִׁלְיָא חוֹשְׁשִׁין לַשִּׁלְיָא וַהֲרֵי הוּא כְּוָלָד אַחֵר וְאֵין אוֹמְרִין זוֹ שִׁלְיַת הַנֵּפֶל. שֶׁאֵין תּוֹלִין אֶת הַשִּׁלְיָא אֶלָּא בְּוָלָד שֶׁל קַיָּמָא. לְפִיכָךְ אִם יָלְדָה וָלָד שֶׁל קַיָּמָא וְהִפִּילָה שִׁלְיָא אֲפִלּוּ אַחַר כ''ג יוֹם תּוֹלִין אוֹתוֹ בַּוָּלָד וְאֵין חוֹשְׁשִׁין לְוָלָד אַחֵר. שֶׁהַוָּלָד קָרַע הַשִּׁלְיָא וְיָצָא:
כסף משנה
14.
When [a woman] miscarries and discharges a placenta, she is governed by the laws that apply to the birth of a male and a female. [The intent is] not that a placenta is a fetus, but there will not be a placenta without a fetus.
If she discharged a fetus and then discharged a placenta, we show concern about the placenta and it is considered as a fetus. We do not say: "This is the placenta of the fetus that miscarried." For we associate the discharge of the placenta only with a viable birth.
Accordingly, if the woman gave birth to a viable child and then discharged a placenta - even after 23 days32Based on Niddah 27a, it appears that this is the maximum number of days granted between a birth and the emergence of the placenta.
In his Kessef Mishneh, Rav Yosef Caro notes that there are authorities who maintain that the 23 days include the day of the birth, while the Rambam maintains that the day of the birth is not included. In his Shulchan Aruch (Yoreh De'ah 194:3), he quotes the Rambam's ruling.
- we assume that [the placenta] came as a result of the child. We do not suspect that there was a second fetus. [Instead, we assume] that the child tore through the placenta and emerged.

הלכה טו
הִפִּילָה שִׁלְיָא תְּחִלָּה וְאַחַר כָּךְ יָלְדָה וָלָד שֶׁל קַיָּמָא חוֹשְׁשִׁין לַשִּׁלְיָא שֶׁהִיא וָלָד אַחֵר וְאֵין תּוֹלִין אוֹתָהּ בַּוָּלָד הַבָּא אַחֲרֶיהָ. שֶׁאֵין דַּרְכָּהּ שֶׁל שִׁלְיָא לָצֵאת לִפְנֵי הַוָּלָד. יָצָאת מִקְצָת הַשִּׁלְיָא בַּיּוֹם הָרִאשׁוֹן וּמִקְצָתָהּ בַּשֵּׁנִי מוֹנִין לָהּ מִיּוֹם הָרִאשׁוֹן וְאֵין נוֹתְנִין לָהּ יְמֵי טָהֳרָה אֶלָּא מִיּוֹם שֵׁנִי לְהַחֲמִיר:
כסף משנה
15.
[When a woman] discharges a placenta and afterwards bears a viable child, we suspect that the placenta came as the result of another fetus.33I.e., the woman had been carrying two fetuses. The emergence of the fetus indicates that she had miscarried and discharged one previously. We do not associate it with the child that was born afterwards, for it is not usual for the placenta to emerge before the fetus.34Since the fetus is carried within the placenta, in a viable birth, the placenta will never emerge before the fetus carried within it.
If a portion of the placenta emerges on Sunday and a portion emerges on Monday, we count [her days of impurity] from the first day and we count her days of purity only from the second day as a stringency.35I.e., as soon as the first portion of the placenta emerges, the woman becomes impure. Nevertheless, her days of purity do not begin until the appropriate time (7 or 14 days) passes after the second day. And they end after 40 or 80 days from the first day, not from the second day.

הלכה טז
הִפִּילָה דְּמוּת בְּהֵמָה חַיָּה וְעוֹף וְשִׁלְיָא קְשׁוּרָה בּוֹ אֵין חוֹשְׁשִׁין לְוָלָד. וְאִם אֵינָהּ קְשׁוּרָה בּוֹ מְטִילִין עָלֶיהָ חֹמֶר שְׁתֵּי וְלָדוֹת שֶׁאֲנִי אוֹמֵר שֶׁמָּא נִמּוֹחַ שַׁפִּיר מְרֻקָּם שֶׁהָיָה בְּשִׁלְיָא זוֹ וְשֶׁמָּא נִמּוֹחָה הַשִּׁלְיָא שֶׁל שַׁפִּיר זֶה שֶׁהוּא דְּמוּת בְּהֵמָה וְחַיָּה:
כסף משנה
16.
If [a woman] miscarries and discharges something resembling an animal, beast, or fowl and a placenta is connected to it, we do not suspect that there is [another] fetus.36As stated in Halachah 8, the discharge of these type of creatures does not render the woman impure. When she discharges a placenta that is connected to them, we assume that they were carried within the placenta. Hence, just as they do not render the woman impure, the placenta also does not.
Although the Shulchan Aruch (Yoreh De'ah 194:7) cites this law without qualification, the Siftei Cohen 194:7 states that just as we are stringent in the present era with regard to the law stated in Halachah 8, we are stringent with regard to this law and rule that the woman is impure.
If they are not connected to [the placenta], we treat it with severity as if there were two fetuses. For we say that maybe the fetus that was carried in this placenta became effaced, and maybe the placenta of this fetus that appears like an animal or beast became effaced.37I.e., we are concerned with the possibility that the woman was carrying two fetuses. Although only one fetus - the animal-formed one - and one placenta emerged, we suppose that originally there was another fetus and another placenta and they were effaced. We assume that the fetus that was effaced was ordinary and hence, the woman is considered as impure.

הלכה יז
כָּל אֵלּוּ שֶׁחוֹשְׁשִׁין לְשִׁלְיָא אֵין נוֹתְנִין לָהֶן יְמֵי טֹהַר. וְכָל מִי שֶׁהִפִּילָה דָּבָר שֶׁאֵינוֹ וָלָד אוֹ שַׁפִּיר בְּתוֹךְ אַרְבָּעִים יוֹם שֶׁעֲדַיִן לֹא נִגְמְרָה צוּרָתוֹ אִם יָצָא עִמּוֹ דָּם הֲרֵי זוֹ נִדָּה אוֹ זָבָה. וְאִם יָצָא יָבֵשׁ בְּלֹא דָּם הֲרֵי זוֹ טְהוֹרָה:
כסף משנה
17.
In all instances when we are concerned that [the emergence of] a placenta [indicates that a fetus emerged previously], a woman is not given days of purity.38I.e., the forty or eighty day period when uterine bleeding does not render a woman impure is not granted in this situation, for we suspect that perhaps the woman never in fact gave birth.
[The following laws apply to] every [woman] who miscarries and discharges something that does not resemble a human fetus39As mentioned in Halachah 8. or a fetus that is within 40 days of conception whose form has thus not been completed.40As mentioned in Halachah 2. If [the emergence of] the fetus was accompanied by bleeding, the woman is either a niddah or a zavah.41The ruling depends on the day of her personal cycle on which the woman miscarries: Is it one of the days of niddah or one of the days of zivah? If it emerged dry, without any bleeding, she is pure.42This ruling depends on our Sages' statement (Niddah 21a) that it is possible for the uterus to open without the woman experiencing any bleeding.
This statement is the subject of a difference of opinion in the Talmud and there are some Rishonim who follow the other position and therefore rule that the woman is impure. The Shulchan Aruch (Yoreh De'ah 194:2) follows this view and rules that even if the woman does not notice any bleeding, she must assume that bleeding did in fact take place.

הלכה יח
מִי שֶׁיָּלְדָה זָכָר וּנְקֵבָה תְּאוֹמִים תֵּשֵׁב לִנְקֵבָה. יָלְדָה טֻמְטוּם אוֹ אַנְדְּרוֹגִינוּס תֵּשֵׁב לְזָכָר וְלִנְקֵבָה. יָלְדָה תְּאוֹמִים אֶחָד זָכָר וְהַשֵּׁנִי טֻמְטוּם אוֹ אַנְדְּרוֹגִינוּס תֵּשֵׁב לְזָכָר וְלִנְקֵבָה. הָאַחַת נְקֵבָה וְהַשֵּׁנִי טֻמְטוּם אוֹ אַנְדְּרוֹגִינוּס תֵּשֵׁב לִנְקֵבָה בִּלְבַד. שֶׁהַטֻּמְטוּם וְהָאַנְדְּרוֹגִינוּס סָפֵק הֵן שֶׁמָּא זָכָר הֵן שֶׁמָּא נְקֵבָה:
כסף משנה
18.
When a woman gives birth to twins - a boy and a girl - she is governed by the laws that apply to the birth of a female.43I.e., she must observe 14 days of impurity and then is given 66 days of purity. We do not restrict her to 26 days because of the birth of the boy. If she gives birth to a tumtum44A person whose genital area is covered by a mass of flesh and thus it is impossible to determine his or her gender. or an androgynus,45A person who has both male and female sexual organs. There is an unresolved halachic question with regard to the classification of such a person's gender. she is governed by the laws that apply to the birth of a male and a female.46Since there is a doubt concerning the issue, the woman must observe the stringencies resulting from either option. If she gives birth to twins, one that is male and one that is a tumtum or an androgynus, she is governed by the laws that apply to the birth of a male and a female.47Since it is possible that the tumtum or the androgynus is - or is considered as - a female, the woman must also take the laws governing the birth of a female into consideration. If one [of the twins] is female and one is a tumtum or an androgynus, she is governed by the laws that apply to the birth of a female.48For even if the tumtum or androgynus was considered as a male, there would be no need for any further severity as stated at the beginning of the halachah. For the gender of a tumtum and an androgynus is a matter of doubt: Maybe they are male or maybe female.49In particular, there is a difference between the two. With regard to a tumtum, the child has a specific gender, we simply are not able to identify it. With regard to an androgynus, by contrast, the doubt involves the child's halachic status.

הלכה יט
הָאִשָּׁה שֶׁהֻחְזְקָה מְעֻבֶּרֶת וְיָלְדָה וְאֵין יָדוּעַ מַה יָּלְדָה כְּגוֹן שֶׁעָבְרָה לַנָּהָר וְהִפִּילָה שָׁם אוֹ שֶׁהִפִּילָה לְבוֹר אוֹ שֶׁהִפִּילָה וּגְרָרַתּוּ חַיָּה הֲרֵי זוֹ בְּחֶזְקַת שֶׁהִפִּילָה וָלָד וְתֵשֵׁב לְזָכָר וְלִנְקֵבָה. אֲבָל אִם לֹא הֻחְזְקָה מְעֻבֶּרֶת וְהִפִּילָה וְאֵין יָדוּעַ מַה הִפִּילָה הֲרֵי זֶה סְפֵק יוֹלֶדֶת וְתֵשֵׁב לְזָכָר וְלִנְקֵבָה וּלְנִדָּה:
כסף משנה
19.
When a woman is known to be pregnant miscarries and it is not known what she miscarried, e.g., she passed a river and miscarried there, miscarried into a pit, or miscarried and a beast dragged away the fetus, we assume that she discharged a human fetus.50And not one of the forms mentioned in Halachah 8. Hence, she is governed by the laws that apply to the birth of a male and a female.51Because we do not know the gender of the fetus, she must take both possibilities into consideration. If, however, she was not known to be pregnant, miscarried, and did not know what she miscarried, she is governed by the laws that apply to the birth of a male and a female and those applying to a niddah.52For it is possible that she was less than 40 days pregnant, in which instance the fetus is not considered as being born, and she is governed by the laws applying to a niddah, as stated in Halachah 2.

הלכה כ
כָּל מָקוֹם שֶׁנֶּאֱמַר (ויקרא יב ד) "תֵּשֵׁב" לְזָכָר וְלִנְקֵבָה כֵּיצַד דִּינָה. תִּהְיֶה אֲסוּרָה לְבַעְלָהּ י''ד יוֹם כְּיוֹלֶדֶת נְקֵבָה. שִׁבְעָה הָרִאשׁוֹנִים וַדַּאי. וְהַשִּׁבְעָה הָאַחֲרוֹנִים סָפֵק. וְאֵין נוֹתְנִין לָהּ יְמֵי טֹהַר אֶלָּא עַד אַרְבָּעִים יוֹם כְּיוֹלֶדֶת זָכָר. וְאִם רָאֲתָה דָּם אַחַר הָאַרְבָּעִים עַד שְׁמוֹנִים אֵינוֹ דַּם טֹהַר אֶלָּא סְפֵק דַּם נִדָּה אוֹ סְפֵק דַּם זִיבוּת אִם בָּא מִימֵי הַזִּיבָה כְּמוֹ שֶׁבֵּאַרְנוּ. וְכֵן אִם רָאֲתָה דָּם יוֹם אֶחָד וּשְׁמוֹנִים בִּלְבַד הֲרֵי זוֹ סְפֵק נִדָּה וְתֵשֵׁב שִׁבְעַת יְמֵי הַנִּדָּה שֶׁמָּא נְקֵבָה יָלְדָה שֶׁאֵין לָהּ וֶסֶת נִדּוּת עַד אַחַר מְלֹאת כְּמוֹ שֶׁבֵּאַרְנוּ:
כסף משנה
20.
What are the laws that apply wherever we said: "She is governed by the laws that apply to the birth of a male and a female"? She is forbidden to her husband for fourteen days like a woman who gives birth to a female. The status of the first seven is definite;53For even if the fetus was male, she would be impure for this time. that of the latter seven is doubtful.54For we do not know that the fetus was female.
We do not grant her any "days of purity" beyond the fortieth day [from the birth] as is the law with regard to one who gives birth to a male.55In his Commentary to the Mishnah (Niddah 3:3), the Rambam explains the rationale for this ruling. There is a question of Scriptural Law involved. Whenever doubt arises in such a situation, we follow the more stringent approach. If she discovers menstrual bleeding between the fortieth and eightieth days from birth, it is not "pure blood."56As would be the ruling was she to have given birth to a female. As explained in Chapter 11, Halachah 6, today Instead, because of the doubt, we consider it as niddah bleeding, or zivah bleeding if it comes in the "days of zivah," as we explained.57In Chapter 7, Halachah 12, the Rambam writes that "that any bleeding that a woman discovers after the completion of the days associated with childbirth marks the beginning of her days of niddah." Accordingly, the first time a woman in such a situation discovers uterine bleeding between the fortieth and eightieth day after birth, there is a doubt whether she is a niddah. If she discovers bleeding a second time, the question of whether the doubt involves the niddah or zivah state depends on the day when the bleeding is discovered.
Similarly, if she discovers [uterine bleeding] on the eighty-first day alone, she is considered as a niddah because of the doubt.58I.e., she is not merely a minor zavah.
Apparently, the Rambam's intent is speaking about a woman who discovered uterine bleeding between the fortieth and eightieth day after birth and then a second time on the eighty-first day and according to the niddah-zivah cycle, the eighty-first day is a day of zivah. (For example, she discovered uterine bleeding previously on the seventieth day.). In that instance, there is a doubt whether she is considered a niddah, for if the fetus was female, this would be considered the beginning of the niddah cycle, or a zavah, for if the fetus was male, her cycle would have begun earlier. See the following halachah and notes.
According to this interpretation, however, the word "alone" which the Rambam adds appears to be in error.
She must observe the seven days of niddah. [The rationale is that] perhaps she gave birth to a female and her "days of niddah" do not begin until after the conclusion [of the days of purity], as we explained.59Chapter 7, Halachah 12.

הלכה כא
כָּל מָקוֹם שֶׁנֶּאֱמַר (ויקרא יב ד) "תֵּשֵׁב" לְזָכָר וְלִנְקֵבָה וּלְנִדָּה כֵּיצַד דִּינָה. תִּהְיֶה אֲסוּרָה לְבַעְלָהּ י''ד יוֹם כְּיוֹלֶדֶת נְקֵבָה. וְאִם רָאֲתָה דָּם בְּיוֹם אֶחָד וּשְׁמוֹנִים הֲרֵי זוֹ סְפֵק נִדָּה. וְכֵן אִם רָאֲתָה בְּיוֹם ע''ד וּבְיוֹם פ''א הֲרֵי זוֹ סְפֵק נִדָּה. וְכֵן אִם רָאֲתָה בְּיוֹם אַרְבָּעִים וְאֶחָד אַף עַל פִּי שֶׁרָאֲתָה בְּיוֹם ל''ד הֲרֵי זוֹ סְפֵק נִדָּה וַאֲסוּרָה לְבַעְלָהּ עַד לֵיל אַרְבָּעִים וּשְׁמוֹנָה כְּיוֹלֶדֶת זָכָר. וְאֵין נוֹתְנִין לָהּ יְמֵי טֹהַר כְּלָל כְּנִדָּה. וַהֲרֵי הִיא כְּמִי שֶׁלֹּא יָלְדָה. וְכָל דָּם שֶׁתִּרְאֶה מִיּוֹם שֶׁהִפִּילָה עַד שְׁמֹנִים יוֹם אִם בָּא בִּימֵי נִדָּתָהּ הֲרֵי זוֹ סְפֵק נִדָּה מֵאַחַר הַשִּׁבְעָה מִיּוֹם שֶׁהִפִּילָה. וְאִם בָּא בִּימֵי זִיבָתָהּ הֲרֵי זוֹ סְפֵק זָבָה שֶׁכָּל יְמֵי מְלֹאת אֵין בָּהֶן וֶסֶת. וְכֵן אִם רָאֲתָה בְּיוֹם אֶחָד וּשְׁמוֹנִים עֲדַיִן הִיא מְקֻלְקֶלֶת וְתִהְיֶה סְפֵק נִדָּה כְּמוֹ שֶׁבֵּאַרְנוּ אַף עַל פִּי שֶׁלֹּא רָאֲתָה אֶלָּא יוֹם אֶחָד וּכְשֶׁיִּקָּבַע לָהּ הַוֶּסֶת אַחַר הַשְּׁמוֹנִים יָסוּר קִלְקוּלָהּ וְתַחֲזֹר לִהְיוֹת נִדָּה וַדָּאִית אוֹ זָבָה וַדָּאִית. וְכֵן מִיּוֹם שֶׁהִפִּילָה עַד שִׁבְעָה יָמִים וְתִהְיֶה נִדָּה וַדָּאִית אִם הִפִּילָה בְּתוֹךְ יְמֵי נִדָּתָהּ כְּמוֹ שֶׁבֵּאַרְנוּ:
כסף משנה
21.
What are the laws that apply wherever we said: "She is governed by the laws that apply to the birth of a male and a female and those applying to a niddah"? She is forbidden to her husband for fourteen days like a woman who gives birth to a female. If she discovers blood on the eighty-first day, there is a doubt whether she is a niddah.60The Rambam is speaking about a situation when a woman discovers uterine bleeding for the first time after a miscarriage. Ordinarily, her niddah cycle would start at that time. Nevertheless, since the possibility exists that her miscarriage did not involve a fetus, she must continue her previous reckoning of the "days of niddah" and the "days of zivah."
Similarly, if she discovered uterine bleeding on the seventy-fourth day and the eighty-first day, there is a doubt whether she is a niddah.61If the fetus was male, the bleeding on the seventy-fourth day would have been considered the beginning of her "days of niddah" and the eighty-first day, the beginning of her "days of zivah." Thus she would be only a minor zavah. Nevertheless, there is also a possibility that the fetus was female. In such an instance, any bleeding before the eighty-first day is insignificant and the eighty-first day begins the niddah cycle. Hence we rule more stringently and consider her a niddah, because of the doubt. Similarly, if she discovered [uterine bleeding] on the forty-first day, there is a doubt whether she is a niddah even though she discovered bleeding on the thirty-fourth day. She is forbidden to her husband until the forty-eighth day, as is the law for a woman who gives birth to a male.62This would be the law were we certain that she had miscarried a male fetus. Her status is doubtful, for it is possible that her miscarriage is not considered a birth at all. In that instance, the bleeding would be either niddah or zivah bleeding, depending on her cycle.
We do not grant her any "pure days" at all, like a niddah. [The following rules apply with regard to] any bleeding that she discovers from the day on which she miscarried until the eightieth day beginning from seven days after she miscarried. If it is discovered in her "days of niddah, she is a niddah, because of the doubt. And if it is discovered in her "days of zivah," she is a zavah, because of the doubt. For throughout the days after birth, [the previous patterns concerning] the expected times of menstruation do not apply.63I.e., were we to know for certain that she had given birth, there would be no concept of days of niddah and days of zivah. Hence, in the present situation, although the woman must observe the stringencies of niddah and zivah, it is only because of the doubt.
Similarly, if she discovers uterine bleeding on the eighty-first day, her situation is still problematic and she must consider herself a niddah because of the doubt as explained [above]. [This applies] even if she discovers bleeding for only one day. When she establishes a pattern of menstruation after eighty days, her difficulties will cease and she will be either definitely a niddah or definitely a zavah.64Depending on the day of her cycle on which the bleeding is discovered. Similarly, from the time she miscarried for seven days, she will be definitely impure [like] a niddah65Either because of the miscarriage or because the bleeding is considered as blood of niddah. Either way, she is definitely impure for seven days. if she miscarried in the midst of her days of niddah, as we explained.66In Halachah 20.

קדושה הלכות איסורי ביאה פרק י
Kedushah Issurei Biah Chapter 10