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Zev Farber





Postpartum Impurity: Why Is the Duration Double for a Girl?



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Zev Farber





Postpartum Impurity: Why Is the Duration Double for a Girl?






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Postpartum Impurity: Why Is the Duration Double for a Girl?

Compared to the birth of a son, Leviticus 12 requires a double-period of purification upon the birth of a daughter. Interpreters in antiquity offered two basic models to explain this. The first approach was to utilize biological “knowledge,” the second was to ground the law in the biblical story of Adam and Eve.


Postpartum Impurity: Why Is the Duration Double for a Girl?

Leviticus 12 lays out the three-step purification procedure required of a woman who gives birth: A period of impurity, a period of ṭahara (meaning either purity or purification), and a ḥaṭṭʾat (sin or purification) offering.

The length of the process, however, is dependent upon the gender of the child. If the child is male, the period of impurity is one week, like that of a menstruant (v. 2), and the period of ṭaharah is 33 days, equaling 40 days in total, a number of symbolic import. If the child is female, each segment is double the time frame for the male child: the period of impurity is two weeks, the period of ṭaharah is 66 days, and the entire period is 80 days.

Ancient and medieval Jewish interpreters struggled to explain the different time periods for each sex.[1]

A Woman’s Oath and the Gender that Brings More Joy

In traditional Jewish circles, the best-known explanation appears in the Talmud, in which R. Shimon bar Yochai explains that a parturient woman must bring a sin offering because she swears never to sleep with her husband again due to the pain of childbirth.[2] It continues with a follow up question and answer (b. Niddah 31a):

"ומפני מה אמרה תורה זכר לשבעה ונקבה לארבעה עשר?"
“And why did the Torah command seven days [of impurity] for [giving birth to] a male child but fourteen days for a female?”
"זכר שהכל שמחים בו מתחרטת לשבעה נקבה שהכל עצבים בה מתחרטת לארבעה עשר."
“Since everyone is excited about a male child, she has remorse [from her oath] in a week. But for the female, where everyone is upset, it takes fourteen days for her to have remorse.”

Notably, even as R. Shimon is taking into consideration the woman’s feelings and her experience of pain, he assumes automatically that even the mother strongly prefers having a son over having a daughter. The explanation here may be meant tongue-in-cheek.[3] In any event, it is not reflective of the major thrust of pre-modern explanations.[4]

Biological Explanation 1: Parallels the Formation of the Fetus

One approach to understanding the details of the distinction between post-partum laws for male and female babies was to look for rational or biological reasons. The earliest example of this approach can be found in Philo (ca. 20 B.C.E.—ca. 50 C.E.). Explaining what it means that God created woman out of the side[5] of man, he writes (Questions and Answers on Genesis 1:25):

Accordingly the lawgiver says that woman was made from the side of man, intimating that woman is a half of man’s body. For this we also have evidence in the constitution of the body, its common parts, movements, faculties, mental vigor and excellence. For all things are seen as if in double proportion. Inasmuch as the molding of the male is more perfect than and double that of the female, it requires only half the time, namely forty days; whereas the imperfect woman, who is, so to speak, a half-section of man, requires twice as many days, namely eighty.[6]

Philo seems to be harmonizing an apparent (to him) contradiction: woman is only part of man, and inferior, but takes twice as long to create. His answer appears to be that since the parts of the man are sounder or more solidly constructed, they are easier to put together.

Melding Torah with Greek Medicine

Leviticus 12, though not mentioned explicitly by Philo, serves as the background for his explanation.[7] Nevertheless, Philo is not working exclusively with the Bible here. Instead, as noted by Iain Lonie (1932-1988), an expert on classical medicine from Otago University, this belief about embryonic development was a general tenet of Greek medicine, widely accepted among Greek natural philosophers:

The belief that male embryos both develop and quicken more rapidly than female was general in antiquity. Galen says that “almost all physicians” were agreed in the opinion, and quotes the statement of Rufus that Diogenes of Apollonia was the sole exception. Extant evidence suggests that the belief, at least in its scientific form, goes back to Empedocles who, according to Oribasius, believed that the male is articulated earlier than the female…[8]

Similarly, Shlomo Naeh, Professor of Rabbinics at Hebrew University, notes that the connection between the post-partum flow and the amount of time it takes for a fetus to form goes back to Hippocrates (5th cent. B.C.E.) On the Nature of the Child:

I brought all of these [details] in to demonstrate that the period when the limbs of the child are articulated occurs at the latest at day 42 for a female and 30 for a male. The proof for this is from the [period of] cleansing from the flow of blood after birth, which lasts for forty-two days after a female and thirty days after a male at the latest.[9]

It is thus natural that a philosopher such as Philo, who wished to explain how the Torah fits with Greek wisdom, would latch onto this theory. As no consensus existed among ancient authorities for the exact time either the bleeding or the articulation of the fetuses takes, Philo was easily able to make use of this model to explain the biblical data.

R. Ishmael

The Greek medical explanation was not limited to Hellenistic philosophical thinkers such as Philo but appears in rabbinic literature as well. The Mishnah discusses the law of a woman who miscarriages on day 41 of her pregnancy (m. Niddah 3:7, Kaufmann MS):

המפלת יום ארבעים, אינה חוששת לוולד; יום ארבעים ואחד, תשב לזכר ולנקבה, ולנידה.
If a woman miscarries on day 40, she need not consider it a fetus; day 41 – she should treat [the fetus] as if it were both a boy and a girl and [the blood] as if it were menstrual.
רבי ישמעאל אומ[ר]: "יום ארבעים ואחד, תשב לזכר[10] ולנידה; יום שמונים ואחד, תשב לזכר ולנקבה ולנידה, שהזכר ניגמר לארבעים ואחד, ונקבה לשמונים ואחד."
Rabbi Ishmael says: “If day 41, she should treat [the fetus] as if it were a boy and [the blood] as if it were menstrual, if day 81, she should treat [the fetus] as if it were both a boy and a girl and [the blood] as if it were menstrual, since a male is completed by day 41 and a female by day 81.”
וחכמ[ים] אמ[רים]: "אחד בריית זכר, ואחד בריית הנקבה, זה וזה לארבעים ואחד."
The Sages say: “Both the creation of the male and the female is [completed] by day 41.”[11]

From this Mishnah, it appears that R. Ishmael and the Sages agreed about how long it takes for a male fetus to form but disagreed about the female fetus. That R. Ishmael’s biological view is informed by the laws in Leviticus 12 seems clear.[12] The Tosefta (t. Niddah 4:8) even records a disturbing empirical proof to R. Ishmael’s position:

א"ר ישמעאל: "מעשה בקלופטרא מלכת אלכסנדרית שהביאה שפחותיה שנתחייבו מיתה למלך וקרעתן ונמצא הזכר נגמר לארבעים ואחד ונקבה לשמונים ואחד."
R. Ishmael said: “It happened with Cleopatra queen of Alexandria that she brought forward her handmaidens, who had been sentenced to death, to the king. He ripped them open and found that the male was complete at 41 days and the female at 81.”[13]

The Tosefta’s attempt to have R. Ishmael prove the point empirically demonstrates that the axis of this debate was perceived to be biological and not just exegetical.[14]

The position that a male is formed in 40 days and a female in 80 continues into the medieval period in the commentaries of R. Abraham Ibn Ezra (1089-1167)[15] and Don Isaac Abarbanel (1437–1508).[16]

Biological Explanation 2: Cold Females and Cleansing the Womb

As noted above, the idea that the male fetus is formed more quickly than the female goes back to Empedocles in the 5th century B.C.E., who connected the formation of each sex to one side. As Lonie writes, according to Empedocles:

[T]he parts on the right-hand side are formed earlier than those on the left. This is the natural corollary of his theory that males are formed in the right-hand and warmer side of the womb, and that males are constitutionally warmer than females…”[17]

In the Middle Ages, the great medieval Scottish philosopher, Michael Scot (1180-1250), put forward a revision of this theory, according to which the uterus has seven chambers.[18] If the sperm enters in one of the right chambers, the fetus will be a boy, if one of the left, a girl.

Scott’s theory greatly influenced the Jewish exegetes of the time,[19] who employed this theory to explain the biblical laws of post-partum impurity, by positing that this right/left distinction, in turn, affects the time it takes for the woman’s uterus to be cleansed.

For example, in the comment of the 13th century French exegete, Hezekiah ben Manoach:

כשהיא שוכבת סמוך אחר הבעילה על צלע ימין, הזרע נכנס באותן נקבים של ימין וילדה זכר, וממהרת הטומאה לצאת, ולפיכך אינה טמאה אלא שבעת ימים, וטהרתה לשלשה ושלשים יום, וכשהיא שוכבת סמוך אחר הבעילה על צלע שמאל, הזרע נכנס בנקבים של שמאל ויולדת נקבה, ואין הטומאה ממהרת לצאת, לפיכך טמאה שבועיים.
When she lies on her right side immediately after sex the semen enters the right holes and she gives birth to a male. Hence the impurity hurries out of her and she is only impure for seven days, and her purification lasts thirty-three days. But when she lies on her left side immediately after sex, the semen enters the holes on the left side and she gives birth to a female. Hence the impurity does not hurry out of her and she remains impure for two weeks.[20]

According to this commentator, a woman with a right-sided (=male) pregnancy cleans out her uterus faster than one with a left-sided (=female) pregnancy.

Nahmanides: Ṭaharah=Cleansing

R. Moses Nahmanides (1194–1270), a contemporary of Hizkuni, offers a similar explanation, although without the creative anatomy. He explains that the term ṭaharah in the verse refers to cleansing:

והענין כי צוה ביולדת זכר שתטמא שבעה כנדתה, כי המנהג שתהיה שופעת דם מן המקור, וצוה שתוחיל עוד שלשים ושלשה ימים תשב בביתה לנקות גופה, כי בכל אלה תוציא תמצית הדמים והלחות העכורות המעופשות הבאות מתמצית הדם ואז תנקה מלידה ומבטן ומהריון ותבא בית ה'...
The reason that a woman who gave birth to a male was commanded to be impure seven days like her menstrual period is since it is usual for her to pour blood from the uterus [during this period]. And it was commanded that she sit another thirty three days in her house to cleanse her body, since during this period she will pass the blood essences and dark rotted liquids which come from blood essence, and then she will be clean from her birthing, from her womb and her pregnancy and can come to the house of the Lord…
וטעם הכפל בנקבה: ...הטעם בעבור כי טבע הנקבה קר ולח, והלבנה ברחם האם רבה מאד וקרה, ועל כן ילדה נקבה, ועל כן צריכה נקיון גדול מפני ריבוי הלחות והדם המעופש שבהן, ומפני קרירות כידוע, כי החולים הקרין צריכין בנקיותם אריכות זמן יותר מן החמים.
The reason for the doubling by a female: …the reason is that a female is cold and moist, and the “white”[21] in the womb of the mother is very great and cold, which is why she had a female. Therefore, she requires a great cleansing because of the amount of moisture and rotten blood within her [womb], as well as because of the coldness, as it is known that sick people who are cold require a longer period of cleansing than do warm [people].

According to Nahmanides, the cleansing period allows the “rotten blood and moisture” accumulated in the womb during her pregnancy to remove itself, and this process takes twice as long when the fetus is female.[22]


The biblical laws of purity and impurity are grounded in physical phenomena, and the post-partum impurity seems to be no different.[23] Although, biologically speaking, it is not obvious why postpartum bleeding should be different depending on the gender of the baby, these sages turned to contemporary biological theories to explain it. Since the science of their times was far from empirical, the numbers could be adjusted to fit the biblical source.

Biblical Explanation 1: When Adam and Eve Entered the Garden

A very different approach to understanding the rules of childbirth associated them with stories of Israel’s past,[24] an approach popular in the 3rd cent. B.C.E. book of Jubilees, which embeds all of its laws in the narratives of Genesis and Exodus. [25] In this case, the laws of parturient impurity are presented as part of the story of Adam and Eve in the garden:

3:8 In the first week, Adam and the flank, his wife, were fashioned, and in the second week he (God) showed her to him. And for this reason a commandment was given to maintain [postpartum mothers] – seven days for a male [child] and for a female two seven-day [units] – in their impurity.
3:9 Afterwards, when for Adam forty days had been completed in the land where he had been fashioned, we brought him into the Garden of Eden[26] to till and maintain it. And his wife was brought [there] on the eightieth day. Afterwards, she entered into the Garden of Eden. 3:10 For this reason a commandment was written in the heavenly tablets for the one who gives birth…[27]

At this point Jubilees quotes from Leviticus 12 setting out the laws of postpartum purification. According to this, the first period of impurity is based on the creation of Adam: As he was created at the end of the first week, the birthing mother recreates this period after giving birth to a boy. To commemorate the “showing” of Eve to Adam,[28] which was done at the end of the second week, the mother must remain in the status of impurity for two weeks instead of one. The explanation for why the purification process lasts up to day 40 or 80, depending on the sex, is similarly based on when each was brought into the Garden of Eden, which parallels the Temple in this understanding.

Given that there is no independent source which describes Eve being created at the end of the second week, or the dates when Adam and Eve entered the garden, the passage in Jubilees should be understood as having been written specifically to explain these laws.

This interpretation does not appear in classical midrash, but does make it into the unconventional midrashic work Midrash Tadshe (ch. 15).[29] He quotes it in the name of R. Pinchas ben Yair (ch. 15), an obscure early rabbinic figure connected with mysticism, which appears to be the author’s way of referencing Jubilees, which he seems to have had access to.[30]

Biblical Explanation 2: The Birth of Cain, Abel, and Their Sisters

A variation of the explanation found in Jubilees is found in the sixth century Christian work Conflict of Adam and Eve with Satan.[31] After recording the birth of Cain and his sister Luluwa, the book states:

1:74 Then Adam and Eve (Ḥeiwan) waited until Cain (Qayal) and his sister were forty days old, when Adam said unto Eve: “We will make an offering and offer it up in behalf of the children.” And Eve said, “We will make one offering for the first-born son; and afterwards [=forty days later] we shall make one for the daughter.”[32]

The text continues with Adam and Eve having Abel and his sister.

1:75 When the days of nursing the children were ended, Eve again conceived, and when her days were accomplished she brought forth another son and daughter; and they named the son Abel (Abeil), and the daughter Aklemia. Then at the end of forty days, Adam made an offering for the son, and at the end of eighty days he made another offering for the daughter, and did by them, as he had done before by Cain and his sister Luluwa.[33]

According to this, the purification for girls, and the corresponding sacrifice, occurs later than that of boys because Eve decided to make this distinction upon the birth of her first two sets of twins—Cain and his sister, and Abel and his sister—the first four children ever born.[34]

Biblical Explanation 3: Atonement for the Sin of Eve

The explanations found in Jubilees and in the Christian Conflict of Adam and Eve with Satan did not enter mainstream rabbinic sources. Another connection to the Adam and Eve story, however, was suggested by R. Abraham Saba (1440-1508), a survivor of both the Spanish and Portuguese expulsions, in his Tzeror ha-Mor.

R. Saba suggests that the doubling of post-partum impurity for the birth of girls atones for the sin of Eve. He offers exegetical proof for this claim:

...לא תמצא בקללת אדם הראשון אלא בעצבון תאכלנה. ולכן לזכר לא צוה אלא שבעה ימים. אבל באשה שכפל. ואמר בעצב על עצבונך. אמר בנקבה וטמאה שבועים.
…You will only find in the curse of Adam “you will eat in suffering” (Gen 3:17) [i.e., the word suffering only appears once]. Therefore, for a boy, [God] only commanded [one period of] seven days, but for a woman it was doubled. [In Eve’s curse, God] says “in suffering” in addition to “your suffering” (Gen 3:16) to say that for a female, she should be impure for two weeks.

As noted by Alan Cooper, Professor of Bible at the Jewish Theological Seminary of America,[35] this comes very close to the Christian concept of original sin, according to which all humans are born tainted with the sin of Eve.[36]

The idea that post-partum impurity is the result of original sin[37] was further built upon by R. Ephraim of Luntshitz (1550–1619), in his commentary on the Pentateuch Keli Yaqqar (ad loc.):

אומר אני שכל זה נמשך בדרך טבע מן חטא הקדום, כמו שנאמר "וטהרה ממקור דמיה", כי החטא הקדום של חוה הוא מקור נפתח לדמים טמאים אלו... כי כל הנשים צריכין טהרה על חטא ראשון אשר ממנו נתפשטה הטומאה והזוהמא בעולם וגרם לכל הנולדים טומאת שבעה...[38]
I say that all of this stems naturally from the ancient sin, as it says: “and she will be purified from the source of her blood,” for the ancient sin of Eve is the source which opened all of these impure bloods… For all women need purification for the ancient sin from which the impurity and the filth spread across the world, and caused all who are born a seven-day impurity…

R. Ephraim goes on to say that the double impurity is because giving birth to a girl increases impurity in the world:

וטעם לטומאת שבועים לאשה עצמה בלידת נקיבה, דין הוא שתהיה לאשה טומאת פי שנים כנגד שתי נקיבות, כי כל נקיבה בפני עצמה נמשך לה טומאת שבעה מן חטא הקדום על כל הנקיבות שבעולם, על כן מן הראוי שתטמא י"ד ימים: שבעה של עצמה ועוד שבעה של בתה, כי הוסיפה בעולם טומאה על טומאתה...
And the reason for the two week impurity for the woman herself who gives birth to a female is that it is reasonable that a woman should have double the impurity parallel to the two females, for the seven day impurity is spread to each female from the ancient sin, upon all females in the world. Therefore, it is fitting that she be impure for fourteen days: Seven for herself and another seven for her daughter, since she has now added an extra impurity in the world in addition to her own impurity…[39]

Notably, while the approaches of Jubilees, Conflict, and the medieval approach of R. Saba and R. Ephraim are all different, each ties the laws into the story of Adam and Eve, and each believes that an inexplicable law can be justified by connecting it to events from the past.

Exegesis Trumps Old Medicine

“The laws concerning purification after parturition pose a challenge to modern sensibilities” writes Alan Cooper.[40] Apparently, they bothered ancient authorities as well, though for different reasons. As noted, the most natural explanation was to look for a biological basis, the circularity of which would not have been obvious to the ancient and medieval scholars the way it is to the modern readers, as the former were not familiar with scientific method.[41]

Nevertheless, this approach did not have universal appeal, since it lacks meaningfulness or religious significance. Practical explanations for commandments may have been popular with some authorities, but they were distinctly unpopular with others, especially those of a mystical bend.[42] For that reason, many sages preferred the non-biological model, that the distinction between the impurity for male and female children was not built into their physical bodies but into the history of their creation, going back to the original pair of male and female, Adam and Eve.


April 23, 2020


Last Updated

August 4, 2020


View Footnotes

Dr. Rabbi Zev Farber is a fellow at Project TABS and editor of He holds a Ph.D. from Emory University in Jewish Religious Cultures (Hebrew Bible focus) and an M.A. from Hebrew University in Jewish History (biblical period focus). In addition to academic training, Zev holds ordination (yoreh yoreh) and advanced ordination (yadin yadin) from Yeshivat Chovevei Torah (YCT) Rabbinical School. He is the author of Images of Joshua in the Bible and their Reception (De Gruyter 2016) and editor (with Jacob L. Wright) of Archaeology and History of Eighth Century Judah (SBL 2018).