Sex on 4/15 and sex on 5/4, sono 6/18 7wk 4 days, which date did i concieve? thanks in advance

May 4: Is closest to the correct date; if the ultrasound was at all accurate then 4/15 would be impossible. Hope that's good news. You didn't give your last menstrual period dates, that's also very helpful.

Subtract 2 weeks: From your gestational age (at 7w4d would say 5w4d). This is the conception date, roughly. Its not the date of intercourse but sperm can live 5-7 days in the reproductive tract while the egg lives only for 24 hours.Sex after conception date would not be the date. Good luck.