4 weeks pregnant
At 4 weeks pregnant, the tiny ball of cells has just implanted in the wall of the uterus. You're in the first trimester, about 2 weeks after conception, because pregnancy is counted from the first day of your last period.
Not sure how far along you are? Try the pregnancy week calculator, or get a free ultrasound at a local pregnancy center.
What's developing at 4 weeks
- The ball of cells (called a blastocyst) reaches the uterus and buries itself in the uterine wall.
- It sticks tightly to the wall of the uterus and begins getting nourishment from the mother's blood.
- The inner cells will become the embryo. The outer cells will become the membranes that nourish and protect it.
Week 4 is about when a period would be due, so it's often when people first wonder if they're pregnant. A pregnancy test may first turn positive around this time. If it's negative and your period still doesn't come, test again in a few days.
If you're not sure what to do
You don't have to decide everything today. It can help to know how far along you are, what all of your options are, and what support is out there.
- Your options: parenting, adoption, and what abortion involves
- Financial help in Michigan: Medicaid, WIC and more
- Fetal development week by week: the full timeline
Sources
- MedlinePlus. Fetal development.
- ACOG. How your fetus grows during pregnancy; Abortion language guide.
- ACOG. Methods for estimating the due date.
Common questions
What is developing at 4 weeks pregnant?
How many weeks since conception is 4 weeks pregnant?
How can I find out for sure if I'm 4 weeks pregnant?
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