יורה דעה שט״וYoreh De'ah 315

Se’if 1א׳

סָפֵק בְּכוֹר, אֵין הַבְּעָלִים צְרִיכִים לִתְּנוֹ לַכֹּהֵן, אֶלָּא יַשְׁהֶנּוּ עַד שֶׁיִּפֹּל בּוֹ מוּם, וְיֹאכְלֶנּוּ. וְאָסוּר בְּגִזָּה וַעֲבוֹדָה. וְאִם תְּקָפוֹ כֹּהֵן, אֵין מוֹצִיאִין אוֹתוֹ מִיָּדוֹ. הַגָּה: וְיֵשׁ אוֹמְרִים דְּמוֹצִיאִין אוֹתוֹ מִיַּד הַכֹּהֵן (טוּר בְּשֵׁם הָרֹא"שׁ) וְכֵן הִלְכְתָא. וַאֲפִלּוּ אִם נְתָנוֹ לוֹ הַיִּשְׂרָאֵל בַּטָּעוּת, שֶׁהָיָה סָבוּר שֶׁצָּרִיךְ לִתְּנוֹ לוֹ, וְאַחַר כָּךְ נוֹדַע לוֹ, צָרִיךְ הַכֹּהֵן לְהַחֲזִיר לוֹ (פִּסְקֵי מהרא"י סִימָן קס"ו).

A doubtful firstborn — the owners need not give it to the priest; rather he keeps it until a blemish falls in it, and eats it. And it is forbidden in shearing and in work. And if a priest seized it, they do not take it out of his hand. Hagah [Rema]: And some say that they do take it out of the hand of the priest (Tur in the name of the Rosh), and so is the halachah. And even if the Israelite gave it to him in error, thinking that he was bound to give it to him, and afterwards it became known to him, the priest must return it to him (Piskei Maharai, siman 166).

Se’if 2ב׳

יוֹצֵא דֹּפֶן וְשֶׁנּוֹלַד אַחֲרָיו דֶּרֶךְ רֶחֶם, שְׁנֵיהֶם אֵינָם בְּכוֹר; אֲפִלּוּ יָלְדָה נְקֵבָה תְּחִלָּה דֶּרֶךְ דֹּפֶן, וְזָכָר אַחֲרֶיהָ דֶּרֶךְ רֶחֶם, כֵּיוָן שֶׁקְּדָמוֹ אַחֵר. בְּכוֹר שֶׁהוּא טֻמְטוּם, הֲרֵי זֶה סְפֵק בְּכוֹר וְיֵאָכֵל בְּמוּמוֹ לִבְעָלָיו. וְדַוְקָא בְּמֵטִיל מַיִם בִּמְקוֹם נַקְבוּת, אֲבָל אִם מֵטִיל מַיִם בִּמְקוֹם זַכְרוּת, בְּכוֹר וַדַּאי הוּא וְצָרִיךְ לִתְּנוֹ לַכֹּהֵן (טוּר בְּשֵׁם הָרֹא"שׁ וְלֹא כְּרַמְבַּ"ם).

One brought out through the wall of its mother's belly, and the one born after it by way of the womb — neither of them is a firstborn; even if she bore a female first by way of the wall and a male after her by way of the womb, since another preceded it. A firstborn that is a tumtum (one whose sex cannot be determined, the flesh covering the place of the sex) — this is a doubtful firstborn, and it is eaten in its blemish by its owners. And this is specifically where it passes water from the place of femaleness; but if it passes water from the place of maleness, it is a certain firstborn and he must give it to the priest (Tur in the name of the Rosh, and not as the Rambam).

Se’if 3ג׳

אַנְדְּרוֹגִינוּס הוּא סָפֵק בְּכוֹר, וְיֵאָכֵל בְּמוּמוֹ לַבְּעָלִים.

An androginos (one bearing the signs of both sexes) is a doubtful firstborn, and it is eaten in its blemish by the owners.