The question is... Should a woman consume a carcinogen 21 days out of the month so she can have sex during the 7 days she is most likely to conceive?
The fallacy of the argument is that fertility should never be considered a disease that needs treatment.
The pill is a carcinogen? Well, maybe...everything else seems to be.
Perhaps you could ask, “Should men use a condom during the week a woman is fertile?”