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 you are vomiting often, cannot keep food or fluids down, have very dark urine or feel dizzy, contact your doctor or maternity unit today — there are safe treatments for severe pregnancy sickness.
When to get help now
Call emergency services now or go to an emergency department now if you have sudden, severe tummy pain, pain in the tip of your shoulder, feel very weak, faint or dizzy, or have heavy bleeding that soaks a pad soon after putting it on. For lighter bleeding or spotting, or pain low down on one side, contact your doctor, maternity unit or an early pregnancy unit today.
Sizes and milestones are typical ranges — every pregnancy runs on its own clock. Educational content; your prenatal care team's guidance always comes first.