Even though almost all healthcare providers measure your pregnancy by the date of your last menstrual period (LMP) — because that’s the easiest and surest way to get a definite base start of a timeline — you might be wondering, “exactly when did I conceive” for your own purposes of tracking things. With all the cool technology out there these days, some women want to be able to start tracking their pregnancies and symptoms right away, even before getting an estimated due date from their doctors.
Knowing when you ovulated is pretty much a must if you want to know exactly when you conceived (give or take a day or two). So other than taking an ovulation test, how can you be sure? Most women have a period every 28 days, but that's just an average, according to Dr. Sherry Ross, OB-GYN and women’s health expert at Providence Saint John’s Health Center in Santa Monica, California. And Ross tells Romper that ovulation is when your egg is available to be fertilized within 24 to 36 hours, and it occurs approximately 14 days before you get your period. So when you’re using the following methods of calculating when you conceived, count back 14 days from when you were supposed to start your period — that’s a pretty good start to give you a general idea of when you ovulated and can help you determine a due date via app, planner, or website.