IF: Am I eligible for the family allowance if my partner or I are expecting a child at the point of time of the deadline?

No, you are noThe familiy allowance will be paid in case of having 'Dependent children who are actually being maintained by the researcher' at the day of the deadline, without a change of status during the duration of the fellowship. Being pregnant does not qualify you e.g. for child benefit and other services, and thus it does make a researcher eligible for the family allowance.
(Source: NCPs and Guide for Applicants for IF)