In Bentching (grace after meals) - both in the Ashkenazic and in the Sefardic version - we say V'Al Brischa SheChasamta Bivsoreinu - ועל בריתך שחתמת בבשרנו - "and for Your covenant, which you sealed on our flesh". This refers, presumably, to the Brit Mila. Does a lady say these words? Why?
The Mishna Berura says:
Loosely translated: "These days the Minhag is that women also say "for the covenant...", and it refers to the covenant of the Males, upon whose flesh the covenant is signed. And [the same applies to] "for the Torah..." that the Males learn, for in the merit of the Males' Torah and [the Males'] Bris the Jewish people [which includes the woman] merited the Holy Land. Additionally, women also have a commandment to study the Mitzvos [in the Torah] that are pertinent to them, to know how to perform them." (translation & square brackets mine)
That bris does not necessarily mean the one that a young boy gets at the age of 8 days.
It could just be referring to the covenant with Hashem to fulfill all of the commandments.
Possible answer from here [Rabbi Baruch Epstein]: