Your Baby: How Old Is Your Baby
When conception takes place, it happens midway in your menstrual cycle or at approximately 2 weeks. When you calculate your due date, that 2 weeks is counted in the calculation, therefore your estimated due date will span 40 weeks (dating back to your last period), instead of the 38 weeks since conception.

Your Body: The ABCs Of Conception
Some women have no idea they've conceived at this early date, while others can tell the exact moment it happened. Either way, conception is a magical moment for a couple, especially a woman, whose body is going to grow and change in ways never thought possible.

If you're curious about conception, here's what you need to know in a nutshell. During ovulation, which usually happens mid-cycle (on day 14 of a 28-day cycle), one of your eggs is carried into the nearest Fallopian tube. If a man's sperm makes its way to the same spot within the next 12 to 24 hours, it may fertilize that egg. You're not actually pregnant until the fertilized ovum, called a zygote, travels the rest of the way down the Fallopian tube and attaches itself to the wall of your uterus.

The catch: The average egg lives only 24 hours and the average sperm lives for 24 to 48 hours, so they have to get acquainted during the first few hours after sex if you're going to conceive. The moral of the story: If your goal is to get pregnant, you should aim to make love at least every other day during the middle of your cycle.

Weekly Tip
It might be a few more weeks until you miss a period - or notice one of the other signs of pregnancy -- and suspect that you're pregnant. So have a home pregnancy test on hand, but hold off using it until four to seven days after you would expect your period to begin. Waiting it out will help ensure that you get the right results.