This is as it is taught in a baraita (Tosefta 9:5): In a case where one said: Whoever informs me as to what opened my wife’s womb, i.e., what the sex of her child is, if it is a male, the one who informs me shall receive one hundred dinars. Therefore, if the wife gave birth to a male, the one who informed him receives one hundred dinars. If he also said: If it is a female he shall receive one hundred dinars, if she gave birth to a female, he receives one hundred dinars. If she gave birth to a male and a female, he receives only one hundred dinars.

The Gemara challenges: But since he did not say anything about a male and a female, if she gave birth to a male and a female, he should not receive anything. Why does the baraita state that he receives one hundred dinars? The Gemara answers: This is referring to where he also said: If she gives birth to a male and a female he shall also receive one hundred dinars. The Gemara asks: But if he stated all of the possibilities, what did his stipulations serve to exclude? The Gemara answers: They serve to exclude a case where she gives birth to a non-viable newborn, in which case he receives nothing.

§ The Gemara relates: There was a certain man who said to his wife: My property is given to the one with whom you are pregnant. Rav Huna said: This is a case of one who transfers ownership of an item to a fetus, and in the case of one who transfers ownership of an item to a fetus, the fetus does not acquire the item.

Rav Naḥman raised an objection to the opinion of Rav Huna from the mishna, which states: With regard to one who says: If my wife gives birth to a male the offspring shall receive one hundred dinars, if she in fact gave birth to a male, the offspring receives one hundred dinars. This indicates that the fetus did acquire the money. Rav Huna said to him: I do not know who taught our mishna. It is not identifiable with a known opinion, and presumably the text has been corrupted.

The Gemara asks why Rav Huna replied in this manner: But let him say to Rav Naḥman: It is in accordance with the opinion of Rabbi Meir, who says: A person can transfer ownership of an entity that has not yet come into the world, e.g., produce that has not yet grown. Just as he maintains that one can transfer ownership of an entity that has not yet come into the world, so too, he maintains that one can transfer ownership of an item to a fetus, who has not yet been born.

The Gemara rejects this explanation: Say that you heard Rabbi Meir express this opinion with regard to transferring ownership of an entity that has not yet come into the world to an entity that is in the world. Did you hear him speak of transferring ownership to an entity that has not yet come into the world, e.g., a fetus?

The Gemara proposes another resolution to Rav Naḥman’s objection: But let Rav Huna say to Rav Naḥman: It is in accordance with the opinion of Rabbi Yosei, who says: A fetus acquires ownership, as we learned in a mishna (Yevamot 67a): With regard to an Israelite woman who married a priest and he died and left her pregnant, the fetus disqualifies its father’s Canaanite slaves from partaking of teruma, because until it is born the fetus is not considered a priest, and the slaves, who are part of its inheritance, are not the slaves of a priest. And the fetus does not enable its mother to partake of teruma, even though it is the child of a priest. This is the statement of Rabbi Yosei. It is evident from this mishna that Rabbi Yosei holds that a fetus inherits its father’s property.

The Gemara rejects this explanation: Inheritance is different, since, unlike a gift, it comes into the possession of the heir by itself, without a formal act of acquisition. Therefore, a fetus can acquire an inheritance, but not a gift.

The Gemara proposes another resolution to Rav Naḥman’s objection: But let Rav Huna say to Rav Naḥman: It is in accordance with the opinion of Rabbi Yoḥanan ben Beroka, who says: The case of an inheritance is not different, and the case of a gift one gives to his heir is not different, i.e., the same halakhot apply to both. As we learned in a mishna (130a): Rabbi Yoḥanan ben Beroka says: If one said about a person who is fit to inherit from him, e.g., one of his sons: This person will inherit all of my property, his statement stands.

The Gemara rejects this explanation: Say that you heard Rabbi Yoḥanan ben Beroka express this opinion with regard to a gift given to an entity that already exists in the world, but does he say anything with regard to a gift given to an entity that has not yet come into the world?

The Gemara proposes another resolution to Rav Naḥman’s objection: But let Rav Huna say to Rav Naḥman: It is in accordance with the opinion of Rabbi Yoḥanan ben Beroka, who compares a gift to an inheritance, and he holds in accordance with the opinion of Rabbi Yosei, that a fetus is fit to inherit. The Gemara rejects this explanation: Who says that Rabbi Yoḥanan ben Beroka holds in accordance with the opinion of Rabbi Yosei?

The Gemara proposes another resolution to Rav Naḥman’s objection: But let Rav Huna say to Rav Naḥman that the mishna is referring not to one who gave a gift to the fetus, but to one who said: I shall give a certain sum to whoever informs me. This person is in the world. The Gemara rejects this explanation as well: If that is so, then concerning that which the last clause of the mishna teaches: And if there is no heir other than the tumtum, the tumtum inherits all of the estate, if the mishna is referring to one who said: I shall give a certain sum to whoever informs me, what is the purpose of mentioning an heir, since the mishna is not discussing a gift to the heir at all?

The Gemara proposes another resolution to Rav Naḥman’s objection: But let Rav Huna say to Rav Naḥman: The mishna is referring to a case where the gift was made after his wife had already given birth but he did not yet know the sex of the baby. The Gemara rejects this explanation as well: If that is so, then concerning that which the latter clause of the mishna teaches: Whatever offspring my wife gives birth to shall receive a certain sum, and she gave birth to a tumtum, the tumtum receives it, there is a difficulty. According to this explanation, the phrase: Whatever offspring my wife gives birth to, is incorrect. The mishna should have said: Whatever offspring my wife gave birth to.