Understanding HCG Levels and Early Pregnancy

Question
First day of LMP was 5/27/04.  HCG Level on July 7th was 2555.  While I know you can't use HCG level to date a pregnancy, is it safe to assume that a sexual encounter exactly 7 days prior to the HCG test would not result in an HCG level that high?  In other words, can I rest easy and be fairly certain that I didn't get pregnant from this encounter on June 30th?
Thanks!


Answer
If you normally have a 28 day cycle (from the first day of your period until the first day of your next period) ovulation occurs on cycle day #14. YOu can only become pregnant if you have unprotected sex on cycle day #13, 14, 15, or 16. If your last period started on May 27, you probably ovulated around June 9 and could have conceived if you had unprotected sex on June 8,9,10, or 11. If you did become pregnant on one of those days, a pregnancy test would not show a positive result until 14-21 days later, or after June 23. The best time to take a pregnancy test would have been after June 30.  A sexual encounter only one week prior to getting a positive HCG value would not have shown a level that high. A level of 2555 HCG would be found in a 3 week gestation.