Pt1 From Conception to Birth: Talmudic Perspectives on Fetal Development and Gender (Niddah 31a-b)
This is the first part of a two-part series. The outline follows.
Outline
A fetus is like a nut floating in water
Fetus Positioning and Labor Pains
Sex during pregnancy
The danger of having sex with one's wife on day 90 of pregnancy
The three partners in creating a person: God, the father, and the mother; and the corresponding body parts
The fetus is created from the clear part of the semen
God counts the times that Jewish people have sex
If the woman emits seed first - baby will be male; if the man emits seed first - female
A woman can only become pregnant by having sex close to the onset of her menstrual cycle; or near the time of her immersion in a ritual bath
The Passage
A fetus is like a nut floating in water
A fetus is compared to a nut floating in water, moving when touched.
ואמר רבי אלעזר:
למה ולד דומה במעי אמו?
לאגוז מונח בספל של מים
אדם נותן אצבעו עליו -- שוקע לכאן ולכאן
And R' Elazar says:
To what is a fetus in its mother’s womb comparable?
It is comparable to a nut placed in a basin full of water, floating on top of the water.
If a person puts his finger on top of the nut, it sinks either in this direction or in that direction.
Fetus Positioning and Labor Pains
The Talmud quotes a baraita about the stages of pregnancy and labor:
During the first trimester of pregnancy, the fetus resides in the lower “compartment” (מדור) of the womb.
During the second trimester, the fetus moves to the middle compartment.
In the last trimester, the fetus resides in the upper compartment.
When it's time for the fetus to be born, it turns upside down, causing labor pains.
The Talmud explains that labor pains are greater for women giving birth to females than for those giving birth to males. The explanation given is that a male fetus is born facing downward, the same position in which a male engages in intercourse;1 while a female fetus is born facing upward, the same position in which a female engages in intercourse, which requires it to turn its face around before birth, adding to the labor pains.
תנו רבנן:
שלשה חדשים הראשונים -- ולד דר במדור התחתון
אמצעיים -- ולד דר במדור האמצעי
אחרונים -- ולד דר במדור העליון
וכיון שהגיע זמנו לצאת, מתהפך ויוצא
וזהו חבלי אשה
והיינו דתנן: חבלי של נקבה מרובין משל זכר
[...]
מאי שנא חבלי נקבה מרובין משל זכר?
זה בא כדרך תשמישו, וזה בא כדרך תשמישו
זו הופכת פניה, וזה אין הופך פניו
The Sages taught in a baraita:
During the first three months of pregnancy, the fetus resides in the lower compartment of the womb;
in the middle three months, the fetus resides in the middle compartment;
and during the last three months of pregnancy the fetus resides in the upper compartment.
And once its time to emerge arrives, it turns upside down and emerges; and this is what causes labor pains.
With regard to the assertion that labor pains are caused by the fetus turning upside down, the Gemara notes: And this is the explanation for that which we learned in a baraita: The labor pains experienced by a woman who gives birth to a female are greater than those experienced by a woman who gives birth to a male.
[...]
The Gemara asks: What is different about the labor pains experienced by a woman who gives birth to a female, that they are greater than those experienced by a woman who gives birth to a male?
The Gemara answers: This one, a male fetus, emerges in the manner in which it engages in intercourse. Just as a male engages in intercourse facing downward, so too, it is born while facing down. And that one, a female fetus, emerges in the manner in which it engages in intercourse, i.e., facing upward.
Consequently, that one, a female fetus, turns its face around before it is born, but this one, a male fetus, does not turn its face around before it is born.
Sex during pregnancy
The Talmud quotes a baraita regarding the stages of pregnancy and having sex:
First trimester: Sex is difficult and harmful for both the woman and the fetus.
Second trimester: Sex is difficult for the woman but beneficial for the fetus.
Third trimester: Sex is beneficial for both the woman and the offspring, resulting in a fair-skinned (מלובן) and strong (מזורז) baby.
תנו רבנן:
שלשה חדשים הראשונים -- תשמיש קשה לאשה, וגם קשה לולד
אמצעיים -- קשה לאשה, ויפה לולד
אחרונים -- יפה לאשה, ויפה לולד, שמתוך כך נמצא הולד מלובן ומזורז
The Sages taught in a baraita:
During the first three months of pregnancy, sexual intercourse is difficult and harmful for the woman and is also difficult for the offspring.
During the middle three months, intercourse is difficult for the woman but is beneficial for the offspring.
During the last three months, sexual intercourse is beneficial for the woman and beneficial for the offspring; as a result of it the offspring is found to be strong and fair skinned.
The danger of having sex with one's wife on day 90 of pregnancy
The Talmud quotes a baraita that states that having sex with one's wife on day 90 of her pregnancy (meaning, the end of first trimester, and beginning of the second) is akin to murder.
The Talmud questions how one can determine the exact day 90. Abaye responds that indeed it's impossible, and one should proceed with having sex without worrying about day 90, and trust in God to prevent harm, as it is written: “The Lord preserves the simple” (Psalms 116:6).
תנא:
המשמש מטתו ליום תשעים, כאילו שופך דמים
מנא ידע?
אלא אמר אביי: משמש והולך, (תהלים קטז, ו) ו"שומר פתאים ה'"
The Sages taught in a baraita:
With regard to one who engages in intercourse with his wife on the ninetieth day of her pregnancy, it is as though he spills her blood.
The Gemara asks: How does one know that it is the ninetieth day of her pregnancy?
Rather, Abaye says: One should go ahead and engage in intercourse with his wife even if it might be the ninetieth day, and rely on God to prevent any ensuing harm, as the verse states: “The Lord preserves the simple” (Psalms 116:6).