It's a possible abortion...
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"The contraceptive pill doesn't always prevent ovulation. As often as 30% of the time, ovulation may occur and if that happens, fertilisation may occur," Dr Jones-Nosacek says.
I think this is a trivial non-issue... If you don't want to take the chance of chemical abortion, don't take the pill... end of story. Though, we may have to change the definition of contraceptive now...