Baby's development
- Zygote forms and begins rapid cell division.
- Genetic blueprint (DNA) is locked in.
T1 · First TrimesterWeek 3 of 40
Fertilization occurs. A single-cell zygote divides as it travels down the fallopian tube toward the uterus.
Progress8% · 37 weeks left
- Baby size
- Pinhead
- Length
- 0.01 cm
- Weight
- —
What's happening to you
- Implantation has not yet begun.
- Very few outward symptoms — you may not know you are pregnant.
Tips for this week
- Avoid X-rays and high-risk medications until you confirm.
- Keep caffeine modest (< 200 mg/day).