[SarahW]

They do interfere with implantation. They both prevent the placenta from infiltrating and multiplying.

At this very early stage it could prevent pregnancy before there is even an identifiable gestational sac.

BTW, ANY conception that doesn't result in a successful implantion is an abortion.

(FWIW, the most common cause of spontaneous abortion in the first trimester is a shallow or botched implantation.)

[conservababeJen]

At this very early stage it could prevent pregnancy before there is even an identifiable gestational sac

Which happens at 6 to 10 days, so at 2 weeks (14 days) it's too late.
eh?