mother-to-be

tuleva|alt=tuleva äiti A pregnant woman, especially one expecting her first child.
2000, Allison England, Aromatherapy and Massage for Mother and Baby, Healing Arts Press (2000), ISBN 0892818980, http://books.google.com/books?id=8y4_rXN3dqIC&pg=PA52 page 52:

The ideal position for a back massage for the mother-to-be is to sit astride a chair supported by cushions.

I don't know how other lesbian, nonbiological mothers-to-be, who tried to get pregnant and could not, might experience their partners' pregnancy.