1st trimester · Week 5
5 weeks pregnant
Neural tube and a forming heart tube
The embryonic period is underway. The neural plate folds toward a tube, and a primitive heart tube begins to take shape. Nausea and profound tiredness may start, though many people still feel well.
How big is your baby at 5 weeks?
- Length
- 0.3 cm
- Weight
- 0 g
- Size
- Lentil
On average about 0.3 cm long and 0 g. Size comparison: Lentil.
These are averages; every baby grows at their own pace.
How is your baby developing at 5 weeks?
The neural tube should close over the coming days — folate matters here. A yolk sac nourishes the disc. Limb buds are not obvious yet. Length is often around 2–4 mm. These are averages; early scans can differ by days.
What changes in your body at 5 weeks?
Rising hCG and progesterone may bring breast tingling, needing to pee more, or food aversions. Mood swings can occur. Some spotting still happens; report heavy bleeding or dizziness.
Tips for this week
Book prenatal care if you have not already. Ask about prenatal vitamins with folic acid (and iodine or iron if recommended where you live). Small frequent meals can help if nausea begins. Seek urgent care for one-sided pain, fainting, or shoulder-tip pain.
