Pregnancy Timeline & Conception Date - Understanding Due Dates

Question
Hello me @nd my girlfriend broke up on the 17th of february we had sex before within @ couple of days but I can't remeber exactly what days, she had sex with someone else on the 17th. Her lmp was on the 2nd of february, when she got her first ultrasound wich was on the 23 of march she was said to be 6 weeks @nd 2 days wich makes her conception date the 7th of febuary but there has been so much confusion with the dates idk what to believe anymore, her doctor says her due date is the 17th of november but her first ultrasound says the 14th is her due date. My question is am I the father of the child if she had sex with someone else on the 17th after we had sex prior if not the day before @ couple of days?

Answer
Based on the information you gave, you certainly might be the father.  However, if she had sex with someone else on Feb 17, then that person might be the father; the dates are just too close.

Dating by u/s is counting from the date of the last period, NOT from the date of conception. So the March 23 u/s really is placing conception around Feb 21 (which could be off by several days) which makes it possible for either one of you to be the father.

I would suggest getting a paternity test done as soon as possible after the birth.

Sincerely,

Dorothy H, LCCE