The famous midrash on Isha Ki Tazria

This post discusses a midrash which contains some adult-themed material. As such, you might wish to skip this post.

The pasuk in the beginning of parshat Tazria reads:

ב דַּבֵּר אֶל-בְּנֵי יִשְׂרָאֵל, לֵאמֹר, אִשָּׁה כִּי תַזְרִיעַ, וְיָלְדָה זָכָר--וְטָמְאָה שִׁבְעַת יָמִים, כִּימֵי נִדַּת דְּו‍ֹתָהּ תִּטְמָא.

2 Speak unto the children of Israel, saying: If a woman be delivered, and bear a man-child, then she shall be unclean seven days; as in the days of the impurity of her sickness shall she be unclean.

On the basis of an extremely close, hyperliteral reading of the phrase אִשָּׁה כִּי תַזְרִיעַ, וְיָלְדָה זָכָר, some suggest that this means that if the woman gives seed (first), then she will bear a male child.

Thus, we have the gemara in Niddah 31a-b:

אמר רבי יצחק אמר רבי אמי אשה מזרעת תחילה יולדת זכר איש מזריע תחילה יולדת נקבה שנאמר (ויקרא יג, כט) אשה כי תזריע וילדה זכר תנו רבנן בראשונה היו אומרים אשה מזרעת תחילה יולדת זכר איש מזריע תחלה יולדת נקבה ולא פירשו חכמים את הדבר עד שבא רבי צדוק ופירשו (בראשית מו, טו) אלה בני לאה אשר ילדה ליעקב בפדן ארם ואת דינה בתו תלה הזכרים בנקבות ונקבות בזכרים (דברי הימים א ח, מ) ויהיו בני אולם אנשים גבורי חיל דורכי קשת ומרבים בנים ובני בנים וכי בידו של אדם להרבות בנים ובני בנים אלא מתוך
שמשהין עצמן בבטן כדי שיזריעו נשותיהן תחלה שיהו בניהם זכרים מעלה עליהן הכתוב כאילו הם מרבים בנים ובני בנים והיינו דאמר רב קטינא יכולני לעשות כל בני זכרים אמר רבא הרוצה לעשות כל בניו זכרים יבעול וישנה

Or, in English translation:

R. Isaac citing R. Ammi⁵⁴ stated: If the woman emits her semen first she bears a male child; if the man emits his semen first she bears a female child; for it is said, If a woman emits semen⁵⁵ and bear a man-child.⁵⁶

Our Rabbis taught: At first it used to be said that 'if the woman emits her semen first she will bear a male, and if the man emits his semen first she will bear a female', but the Sages did not explain the reason, until R. Zadok came and explained it: These are the sons of Leah, whom she bore unto Jacob in Paddan-aram, with his daughter Dinah,⁵⁷ Scripture thus ascribes the males to the females⁵⁸ and the females to the males.⁵⁹

And the sons of Ulam were mighty men of valour, archers; and had many sons, and sons' sons.⁶⁰ Now is it within the power of man to increase⁶¹ the number of 'sons and sons' sons'? But the fact is that because

they contained themselves during intercourse¹ in order that their wives should emit their semen first so that their children shall be males, Scripture attributes to them the same merit as if they had themselves caused the increase of the number of their sons and sons' sons. This explains what R. Kattina said, 'I could make all my children to be males'. Raba stated: One who desires all his children to be males should cohabit twice in succession.

What is the purpose of this midrash? Indeed, Kli Yakar wonders the same. Even if it is medically true, why should the Torah go out of its way to inform us of this. And he gives an answer -- see inside.

I think that one could suggest that this derasha serves a purpose in directing the tzibbur. In a male-dominated society, perhaps many men would be selfish lovers, and the women would seldom acheive orgasm. (This would seem to be the meaning of the woman giving seed.) Here, playing on the prevalent attitude of preferring male children in such a society, and tying it in to a Biblical verse, Chazal give a motivation to making certain that a woman receives the pleasure she is due, for if the man gives seed first, then intercourse in most cases stops at that point.

On the other hand, perhaps it is simply reading in contemporary scientific beliefs into the words of the Torah, as well as giving practical advice to acheive the preferred choice of child. As several commentators note, it works with Greek science. (See here where I try to make something similar to this midrash work with modern science.) To resolve this, we might be able to analyze the gemara in Niddah to see, based on context, what genre of derasha this is, and what the authors of these set of midrashim intend. See for example what R' Yitzchak citing R' Ammi says a bit later on Amud Bet. But see that it is also in a brayta, and see the general theme there. I am not certain how I would resolve this.

This explanation of Isha Ki Tazria as the woman giving seed first is endorsed by Ibn Ezra:
ורבים אמרו:
שהאשה מזרעת תחלה יולדת זכר, על כן וילדה זכר.

ועל כן דעת חכמי יון:
שהזרע לאשה וזרע הזכר מקפיא וכל הבן מדם האשה.

והנה פירוש תזריע –
תתן זרע כי היא כמו הארץ.

endorsed by Seforno:
אִשָּׁה כִּי תַזְרִיעַ וְיָלְדָה זָכָר. כְּבָר אָמְרוּ 'אִשָּׁה מַזְרַעַת תְּחִלָּה יולֶדֶת זָכָר' (נדה פא, א), וְזֶה כִּי אָמְנָם זֶרַע הָאִשָּׁה וְהוּא הַלֵּחוּת הַנִּפְלָט מִמֶּנָּה לִפְעָמִים בְּעֵת הַחִבּוּר לא יִכָּנֵס בִּיצִירַת הַזָּכָר כְּלָל, אֲבָל דָּמָהּ יִתְפָּעֵל וְיִקְפָּא בְּזֶרַע הָאִישׁ, וְכַאֲשֶׁר יִכָּנֵס מִזַּרְעָהּ הַלֵחוּתִיִּי בְּדָמָהּ הַנִּקְפָּא יִהְיֶה בו לַלֵחוּת מותָרִיִי וְיִהְיֶה הַוָּלָד נְקֵבָה.

endorsed by Daat Zekeinim miBaalei HaTosafot, and others.

Meanwhile, Rashbam feels compelled to explain Isha Ki Tazria means that she conceives, and this is the general case, with the pratim being giving birth to a male or female child:
אשה כי תזריע -
כי תתעבר בין זכר בין נקבה. אם זכר תלד, יהא דינו כך. ואם נקבה תלד, כך וכך דינה כולל ואח"כ מפרש.

R' Yonah Ibn Janach, and Aharon ben Yosef the Karaite scholar, explain the pasuk similarly. Their impetus is to counter this famous derasha.