Pregnancy Dating: Estimating Your Conception Date

The gestational age of an embryo or fetus is measured from the first day of the woman's last menstrual period (LMP). This dating system is used because the exact time of conception is often not known.

On average, ovulation occurs 14 days before the start of a woman's period. This means that if your scan showed you were 6 weeks pregnant, you would have conceived about 2 weeks before your LMP.

However, it is important to note that this is just an average. The time of ovulation can vary from woman to woman, and can be affected by factors such as stress, illness, and medication.

If you are unsure of when you conceived, your doctor or midwife can help you determine your gestational age based on your scan results and your menstrual history.