I have recently come upon historical evidence of the mothers of baby boys serving as the sandek(et) during the brit milah.
From page 18 of The Orthodox Jewish Woman and Ritual: Options and Opportunities (Put out by the Jewish Orthodox Feminist Alliance)
A second major figure at a brit is the sandek, or baal habrit, the per- son who holds the baby while the mohel performs the circumcision. Usually this honor is given to a grandfather, great-grandfather, or impor- tant community figure. Can a woman act as sandeket? The first halachik objection to this custom was voiced by Rabbi Meir of Rotenburg in the thirteenth century. Before this time, a woman was able to act as a sandeket or baalat brit. Later Ashkenazi authorities disapprove of a woman acting as sandeket out of fear of intermingling of the sexes. Today, when women and men do interact at both secular and religious events there is room to be lenient with this objection. However, Rabbis may be more stringent with laws regarding intermingling of the sexes when the brit is set in a synagogue, and some mohalim may be uncom- fortable with the idea of a female sandeket.
In the final analysis, the role of sandek is honorary and symbolic and does not affect the status of the child. Certain Orthodox Rabbis today do permit a woman to act as sandeket, and individual Rabbis should be consulted regarding syna- gogue policy. Clearly it would be very meaningful if a grandmother or another significant female figure could act as sandeket.
Does anyone have any knowledge of this practice and a mohel that would perform a brit milah with the mother holding the baby? I know it is rare, but any help would be appreciated!