Boy or girl? The difficulties of early gender prediction | Your Pregnancy Matters | UT Southwestern Medical Center (

Compare this with the bible story of some 3500 years ago, below [Henrew and Englis]


A Prayer in Vain

The Mishnah in Masechet Berachot (54a) states: “If one prays for something that has already passed, this constitutes a prayer in vain.” This is because Hashem will not change something that has already occurred in the past. 

 The Gemara there provides an example: “If one’s wife is pregnant and one says, “May it be Hashem’s will that my wife give birth to a baby boy,’ this is considered a prayer in vain. Rather, one should pray for the future and give thanksgiving for the past.” The reason for this is because one should not pray for past events; the fetus in its mother’s womb is either male or female already, thus, one should not pray for a miracle to occur and change reality. The Gemara (ibid.) continues to provide us with an additional example: “If one enters a city and hears screaming in the city and exclaims, ‘May it be Hashem’s will that these [screams] should not be from my family members,’ this is considered a prayer in vain.”

The Gemara states that Rav Yosef questions this concept from what the Torah states regarding our Matriarch, Leah, “And after this, Leah bore a daughter and she called her name ‘Dinah.’” The Gemara asks, “Following which event did Leah give birth to a daughter?” The Gemara replies, “Rav said: After Leah made her own calculation and said, ‘Twelve tribes are destined to be born from Yaakov. Six have come from me (for she had already given birth to six: Reuven, Shimon, Levi, Yehuda, Yissachar, and Zevulun), four from the maidservants (Bilhah had already given birth to Dan and Naftali and Zilpah had already given birth to Gad and Asher), this amounts to ten. Should my sister Rachel be lesser than the maidservants? (Meaning that if Leah would give birth to the eleventh son, at this point Rachel had not yet given birth to any children and the only thing left for Rachel to bear would be one son; the maidservants, however, had already given birth to two sons each. If so, Rachel would then be lowlier than the maidservants and this would be a terribly hurtful to Rachel. Thus, Leah beseeched Hashem that the child in her womb be a girl, not a boy, so that Rachel may bear two boys.)

Immediately, it (the fetus in Leah’s womb) turned into a girl, as the verse states, ‘And she called her name, ‘Dinah.’” We see from here that it is possible for a boy to turn into a girl or the opposite which seems contrary to the teaching of the Mishnah which states that if one prays that his pregnant wife give birth to a baby boy, this is considered a prayer in vain.

The Gemara answers all this by saying, “We do not announce miracles”; therefore, the miracle which occurred to Leah cannot be used as a comparison for other people. The Gemara offers another answer that the incident with Leah was during the first forty days from conception and a baby’s gender is only determined forty days after conception, when its formation is complete. Therefore, it is permissible to pray for whatever gender one wishes the baby to be within forty days from conception.

Indeed, the Poskim and Maran Ha’Shulchan Aruch (Chapter 230) rule that one may pray for a baby to be either a boy or girl during the first forty days of pregnancy; however, once these forty days have passed, one should no longer pray for this. Rather, one should merely pray that the child be blessed and successful.

It is well-known that our Sages speak very highly about the importance of a woman’s prayer for her child during her pregnancy, that her sons should grow to involve themselves in Torah and fear of Heaven and her daughters should grow up to be like our righteous Matriarchs, good in all aspects, and for all to recognize that they are the blessed children of Hashem.

In the following Halacha, we shall discuss this matter further.