Week by Week
Your Trimester Journey
All 40 weeks with verified baby development, maternal changes, size and weight. Sources: ACOG, WHO, NHS, INTERGROWTH-21st.
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First Trimester · Weeks 1–12
From fertilisation to a fully-formed fetus with a beating heart. Baby develops every major organ system. The most critical period for neural tube and cardiac development — folic acid is essential.
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Second Trimester · Weeks 13–26
The golden period. Morning sickness eases, energy returns, and you'll feel your baby's first movements (quickening). The anatomy scan surveys baby's entire structure in detail.
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Third Trimester · Weeks 27–40
Baby gains weight rapidly, lungs mature, brain develops complex folds. Baby practises all skills for life outside the womb. The countdown to birth begins.