Is the gift (Hibah) of a female slave valid if the donor excepts (stipulates exclusion of) what is in her womb (the fetus)?

Primary text

The stipulation excluding what is in the womb of the gifted female slave is valid, following the analogy (Qiyas) to the ruling regarding the emancipation (I'taq) of a female slave while excluding what is in her womb. This opinion is held according to the view of Ahmad. The rationale is that the gift pertains to the mother while excluding what is in her womb, resembling the act of emancipation. This position is also held by Al-Nakh'i, Ishaq, and Abu Thawr.