First trimester · Week 3 of pregnancy
3 weeks pregnant: body, feeding, and care
The fertilized egg divides as it travels toward the uterus, becoming a blastocyst — a hollow ball of cells that will become the embryo and placenta.
Body and care — week 3
The fertilized egg divides as it travels toward the uterus, becoming a blastocyst — a hollow ball of cells that will become the embryo and placenta. Development notes on this page are general education summarized from ACOG patient-education material; they describe typical development, not your pregnancy specifically. Anatomy and growth are confirmed by your own provider and ultrasounds.
This week's checklist
- Note one body question — sleep, appetite, movement, comfort — and bring it to your next prenatal visit rather than searching it at 3 AM.
- Keep prenatal appointments on the schedule your provider sets; bring your questions list.
- Anything that worries you — bleeding, pain, reduced movement later in pregnancy — goes to your provider or urgent care first, never to a website.
Week 3 questions
What is happening at 3 weeks pregnant?
The fertilized egg divides as it travels toward the uterus, becoming a blastocyst — a hollow ball of cells that will become the embryo and placenta.
Which trimester is week 3?
Week 3 falls in the first trimester (weeks 1–13). See the first trimester hub.
How is a due date calculated?
A due date is typically estimated as 280 days (40 weeks) from the first day of the last menstrual period. It is an estimate — try the client-side due-date calculator; your provider's dating outranks it.
Educational information only — not medical advice. Every pregnancy and every baby develops on their own timeline. If you have any concern, talk to your obstetric provider or your baby's pediatrician.