Why is the zman for tumas leidah of giving birth to a girl longer then that of a boy?
Answer:
Some refer to the opinion of Rabbi Yishmael (Niddah 3:7) who writes that the time for the formation of a boy is 40 days, and a girl 80 days – the difference is reflected in the days of purity and defilement following birth.
However, the Chachamim (in the Mishnah) don’t agree, and I don’t know the reason for this difference.