Pregnancy Week 5 — Baby Development, Size & What to Expect

Week 5 of pregnancy — 1st trimester. Baby is the size of a sesame seed 🌱, approximately 0.2cm long. Heart begins beating. Neural tube forming. Amniotic sac developing. 12% of the 40-week journey complete, 35 weeks remaining.

PREGNANCY WEEK 51st TRIMESTER

🌱

sesame seed

baby is about the size of a sesame seed

WEEK

5

of 40

LENGTH

0.2cm

crown to rump

WEIGHT

tiny

approximate

Progress12% complete
Wk 11st Trimester (Weeks 1–12)Wk 40

35 weeks remaining · Heart begins beating. Neural tube forming. Amniotic sac developing.

WEEK 5 — BABY'S DEVELOPMENT

1ST TRIMESTER · Weeks 1–12

Heart begins beating. Neural tube forming. Amniotic sac developing.

HOW YOU MAY FEEL

Nausea may intensify. Increased urination. Heightened sense of smell.

WEEK 5 KEY FACTS

Gestational age

Week 5

Trimester

1st (T1)

Baby length

0.2cm

Baby weight

tiny

Progress

12% complete

Weeks left

35 weeks

FREQUENTLY ASKED QUESTIONS

What happens at week 5 of pregnancy?

At week 5 of pregnancy (1st trimester):\n\nBaby development: Heart begins beating. Neural tube forming. Amniotic sac developing.\n\nBaby size: sesame seed 🌱\nLength: approximately 0.2cm (crown to rump)\nWeight: approximately too small to measure\n\nPregnancy progress: 12% complete (35 weeks remaining)\n\nGestational age is counted from the first day of your last menstrual period (LMP), not from conception. Week 5 begins on day 29 and ends on day 35 from your LMP.

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Pregnancy week 5 · 1st trimester · Baby size: sesame seed 🌱 · 0.2cm · tiny · Sources: ACOG, WHO fetal growth data