10 WEEKS PREGNANT
The embryo officially becomes a fetus
Baby this week: about 3.1 cm — crown to rump · about 4 g
≈ 3.1 cm — about the size of a kumquat
Illustration enlarged for clarity — the amber marker shows true relative size
Your baby this week
- The medical term switches from 'embryo' to 'fetus' this week
- Fingernails and toenails begin to form
- The outline of the nose and earlobes becomes more defined
- Bones start to harden, beginning the process of ossification
Your body this week
- Some notice their first hint of a baby bump starting to show, though this varies a lot
- Energy levels may still be low, especially if nausea is ongoing
This week's tip: If morning sickness makes it hard to eat balanced meals, focus on whatever nutritious foods you can tolerate right now — variety can wait.
Want the bigger picture — organ development, nutrition, scans and warning signs for this stage? See month 3: The first trimester finish line.
Sizes and milestones are typical ranges — every pregnancy runs on its own clock. Educational content; your prenatal care team's guidance always comes first.