Yevamot 35: Contraception, Talmud-style

The case of a female convert or a freed maidservant... With the inappropriate presumption, though possibly accurate, that prior to their change in status, they were promiscuous, or at least presumed to have been so. Which leads to a discussion of the contraception that promiscuous women would have used. Which is relevant to the discussion when the woman knows her freedom is coming to take great care against getting pregnant. It would seem that R. Yosei contradicts himself in terms of whether the woman needs to wait 3 months... As well as other methods of supposed contraception. Also, a new chapter. The yavam has to wait 3 months after the brother's death to be sure that the widow isn't pregnant. What happens if yibum is done sooner? What if they do chalitzah? What if she is pregnant? What if the baby is born and survives? What if the baby doesn't survive?