How women conceive. Or not.
Robert Martin keeps churning out good articles on sex and evolution. It turns out that women store sperm in their cervix, whose mucus increases the period of sperm viability, allowing conception regardless of when in their cycle they had sex. That has some interesting evolutionary implications. And is one more explanation why all forms of the rhythm method are nigh useless. If you don’t want to conceive, put away the thermometer and run get a modern IUD, which is responsible for the recent decline in unintended pregnancies.