it depends on whether or not you have fertile mucous, and how strong the sperm are. if you're avoiding, a longer time is used, but if you're TTC a shorter time is used. For instance, I'm CTA so I wouldn't DTD w/o a condom if I saw fertile mucous six days out (I have a 6-7 day mucous patch) because there is a chance the sperm could live that long!
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