6 WEEKS PREGNANT
The heart begins its first flutters
Baby this week: about 0.4 cm — crown to rump · under 1 g
≈ 0.4 cm — about the size of a lentil
Illustration enlarged for clarity — the amber marker shows true relative size
Your baby this week
- The heart tube starts contracting, often visible as a flicker on an early ultrasound
- Buds that will grow into arms and legs appear along the sides of the body
- The neural tube finishes closing, and the brain begins dividing into sections
- Tiny pits mark where ears will eventually form
Your body this week
- Morning sickness often starts to show up around now for those who experience it
- Frequent urination can begin even this early as the uterus grows and hormones shift blood flow
This week's tip: If nausea is intense or you can't keep fluids down, tell your care provider — there are safe ways to manage it.
Want the bigger picture — organ development, nutrition, scans and warning signs for this stage? See month 2: The heartbeat becomes real.
Sizes and milestones are typical ranges — every pregnancy runs on its own clock. Educational content; your prenatal care team's guidance always comes first.