Pregnancy and due date question?

Patient: If I had sex with someone February 28th, 2014. Is it possible for them to still be pregnant/have a due date of January 11th 2015?

Symptoms: Pregnancy

Doctor: Hello,No, it is not possible. As by Naegle’s formula if the due date in JAN 11 2015, then the last menstrual period w ould have been on 4th APRIL 2014. This doesn’t make you the father of the baby your partner carries.I hope this answered your query. Your partner would have had her menses in MARCH and then may have conceived in the next cycle in April which clearly indicates that it was not the result of sex on 28th Feb.Wishing you good health,regards