Can the morning after pill bring a false period?

[Mwalsh_]

I had sex on Jan 25 and took the morning after pill the same day. My period came Feb 4, seemed real but I thought it was 4 days early (which could mean my ovulation was actually around Jan 25 and the pill would be too late to work). I had sex again on Feb 14. Ultrasound on Apr 28 put EDD at Nov 8 and LMP at Feb 1. So I was confident that Feb 14 resulted in the pregnancy, but now I am questioning that period based on things I've read about the morning after pill. Does the embryo development start at fertilization or implantation? I.e. could Feb 14 be implantation date and not conception date?

[AnnieBrooke]

Embryo development begins when the sperm meets the egg. When it implants is not significant to the calculation of when conception was. (Is that what you were asking?)

[Mwalsh_]

Hello, yeah basically :) So from EDD of nov 06 it points to Feb 14 sperm-meets-egg (not earlier conception and Feb 14 implantation). So its unlikely that sex in late January resulted in the pregnancy, because the EDD  by ultrasound would be a little earlier? There was also that period in early feb but was just concerned it wasn't real due to the pill. Thank you

[Mwalsh_]

(Nov 6 or Nov 8, has ultrasounds at 7 and 12wk)

[AnnieBrooke]

Yes, an estimated due date of November 6 points to a conception date (which is, sperm-meets-egg date) of February 14. What is being measured is the development of the embryo. That begins when it becomes an embryo and stops being sperm or egg, which happens the moment sperm meets egg and they merge.