3 Weeks Pregnant: When Did I Conceive?
If you are 3 weeks pregnant today, conception most likely happened about 1 week ago. That's because pregnancy is counted from the first day of your last period, roughly two weeks before you actually conceived.
| Weeks pregnant (gestational age) | 3 weeks |
|---|---|
| Time since conception (embryo/fetal age) | about 1 week (7 days) |
| Last period started | about 3 weeks (21 days) ago |
| Trimester | first |
| Weeks until due date | 37 |
Why the numbers don't match
Doctors and midwives count gestational age from the first day of the last menstrual period, because that date is usually known and conception usually isn't. In a 28-day cycle, ovulation and conception happen around two weeks later, which is why fetal age is about two weeks less than the number of weeks pregnant.
If your cycles are longer than 28 days, conception was likely a little more recent; with shorter cycles, a little longer ago.
What's happening at 3 weeks
Most people don't know they are pregnant yet; implantation may only just be happening.
Working out the exact date
To get the actual calendar date of conception, use the pregnancy week calculator with the first day of your last period, or the conception date calculator if you already know your due date.
Pregnancy Week Calculator: See how many weeks pregnant you are today.
Open the calculatorThis article is general information, not medical advice. Talk to a doctor or midwife about your own pregnancy or fertility.