Pregnancy week 4: hCG rising, test positive
hCG levels double every 48-72 hours. Most pregnancy tests detect at this point. Embryo size of a poppy seed.
Where you are in pregnancy
You're in the first trimester. Most morning sickness, fatigue, and adjustment happens here. Risk of miscarriage decreases as you progress through this trimester.
What's happening to baby at week 4
hCG levels double every 48-72 hours. Most pregnancy tests detect at this point. Embryo size of a poppy seed. The full physical and neurological development happening this week is part of a continuous timeline — for the complete picture across all 40 weeks, see the complete pregnancy pillar.
What's happening to your body
Each pregnancy week brings physical changes. Common at week 4: hormonal shifts driving symptoms, blood volume changes, uterine growth (after week 12), or physical preparation for delivery (third trimester). Track symptoms in Wermom App for patterns.
- Continue prenatal vitamin (folic acid most important T1, iron throughout)
- Track symptoms and concerns for next OB visit
- Hydrate (pregnancy increases fluid needs by ~300mL/day)
- Begin or continue safe exercise (150 min/week target per ACOG)
- Mental health check-in
Red flags this week
Always call your provider for: heavy bleeding, severe one-sided pain, severe headache with visual changes, signs of preterm labor, sudden swelling, persistent severe vomiting.
Track week 4 with Wermom App
Week-by-week guidance + symptom tracker + appointment reminders
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