From: Rabbi Moshe Sofer
To: Unknown recipient
The Chasam Sofer responds to three questions about sacrificial law and fetal status: the Rambam cited chulin ba'azarah rather than neveilah because it conveys the practical ruling that the offering is assur behana'ah; one bird chatas suffices for a doubtful miscarriage because a sefeik sfeika eliminates the need for a second offering; and the Rashba's application of Rav Ada bar Masnah's question about a human form in an animal holds even according to the Rabbanan under the Chullin version where permissibility depends on the fetus's hooves.
Source: Shu"t Chasam Sofer YD §12