Medical Questions > Pregnancy Forum > Pregnancy Forum

Calculating Ovulation and Fertile Days for Conception

Must Read
What happens during labor? What do contractions feel like? And how do I know that labor has begun? Read on to learn about birthing basics....
Signs of labor occur after 36 weeks of pregnancy. Learn about the difference between real and false contractions. Plus, we outline signs of delivery complicati...
Almost all women worry about the pain of childbirth. Preparing for childbirth includes thinking about how you'd like to cope with the pain of labor. Read on for...
User Profile
When Did I Conceive
Posted: 07-21-06 5:27pm

------------------------------------------ --------------------------------------
Well im pregnant and Im not sure who the father..First of all ive always had irregular periods. I get my periods every month in a half. So im afraid that the date of conception the Dr. gave me might be wrong..The first day of my last period was april 6th, 2006..The Dr. Said that by the size of the looks like Im about three months. I conceived on may 10, 2006..And my due date is feb 1, 2006..I cheated on my boyfriend with an ex on may 13, 2006..Could it be possible that my ex-boyfriend might be the father?? ..Someone please help..

Did you find this post helpful?

User Profile
replied July 27th, 2006
Pregnancy Answer A1250
The most accurate means for determining paternity is using a DNA test from both men. If your cycles are irregular then it is impossible to determine the date of conception.

Conception occurs soon after ovulation (24 hour at most) . Ovulation usually happens about 14 days before the next period starts (there are always exceptions). The time period between ovulation and the next period is usually constant (about 14 days), no matter how long the cycles last... or if they are regular, or not. That’s why we can determine the day of ovulation (and possible conception) for women with regular periods. For example: if your last period started on the 6th of April and your cycles usually last 32 days, then your next period would come on or around the 7th of May. To calculate the ovulation day we count 14 days backward from the 7th of May... which means that you probably ovulated around the 23rd of April. Two days before and after the 23rd are considered highly possible days for conception, or "fertile" days. In women with irregular cycles, we can’t calculate the ovulation date because we don’t know when the next period will start. So, we don’t have a date from which we will count 14 days backward.

In your case, you can never be sure when you conceived. It was probably somewhere in May. Time distance between 10th and 13th of May is so short that gives, both actual or ex boyfriend, chances to be a father. I think that in your case only DNA-test can tell you who the real father is. The only precise fact that I can give you according to your last period date is that you are 16 weeks pregnant till now.

Did you find this post helpful?
DISCLAIMER: "Ask a Doctor" questions are answered by certified physicians and other medical professionals. For more information about experts participating in the "Ask a Doctor" Network, please visit our medical experts page. You may also visit our Pregnancy , for moderated patient to patient support and information.

The information provided on eHealth Forum is designed to improve, not replace, the relationship between a patient and his/her own physician. Personal consultation(s) with a qualified medical professional is the proper means for diagnosing any medical condition.