How does morning after pill affect 2nd period? got period 1 wk after using morning after pill but 2nd period is a wk late.

Not usually: Emergency contraception can often change the timing of a person's next period but shouldn't affect the one after that. If it's late and you could be possibly pregnant I would considering at least checking a home pregnancy test.

It may effect: period timing up to several months out. Test for pregnancy if you have been sexually active since then.