Tosefta for Bava Batra 283:2
דאמר רב נחמן המזכה לעובר לא קנה לכשתלד קנה ורב הונא אמר אף לכשתלד לא קנה ורב ששת אמר אחד זה ואחד זה קנה
'For. [it was stated.] R. Nahman said: If a person conveys possession. through the agency of a third party. to an embryo.[the latter] does not acquire ownership. [If however, he said].]<span class="x" onmousemove="('comment',' That the child shall acquire possession. ');"><sup>3</sup></span> 'After she will have born'.<span class="x" onmousemove="('comment',' The child to whom the assignment was made. ');"><sup>5</sup></span> [the child] does acquire ownership. But R. Huna said: Even [where he said]. 'After she will have born'. [the child] does not acquire ownership. R. Shesheth however said: Whether he used the one, or the other expression.<span class="x" onmousemove="('comment',' Lit., 'whether this or this'. ');"><sup>6</sup></span> [the child] acquires ownership. Said R. Sheshet: Whence do I derive this? — From the following:<span class="x" onmousemove="('comment',' Lit., 'for it was taught'. ');"><sup>7</sup></span>