QuestionMy last menustral cycle was on 1/01/07. My period ended on 1/04/07. I had sex with my fiancee on 1/06/07, 1/12/07 and 1/17/07. Which date was the more likely date for me to have conceived? I was thinking on 1/06/07 was the date.
AnswerThe most likely date of conception actually depends on how long your average cycle length is, and when in your cycle you usually ovulate. A conception date of 1/6, only five days into your cycle, would be highly unusual, unless you usually have cycles of less than 21 days. If your cycles are closer to the average 28 days long, and your ovulation is around the average day 14, then you most likely conceived after having sex on 1/12. Sperm can survive for up to 4 days, but the egg only lives for 24 hours, so if you ovulated on 1/14 (day 14), having sex on 1/17 would have been too late, but 1/12 would have been close enough.
If you need to pinpoint the date of your pregnancy with greater accuracy, ultrasounds done before 13 weeks are very accurate at determining the age of the fetus.
