Third trimester

Week 33 of Pregnancy

Maternal antibodies begin transferring across the placenta.

Fetal size
Pineapple
Length
43.7 cm
Crown-to-heel
Weight
1.92 kg

Fetal development

  • Maternal IgG antibodies cross the placenta, building passive immunity.
  • The skull is firm but stays flexible for delivery.
  • Lung development is nearly complete.

Maternal changes

  • Pelvic pressure intensifies.
  • Sleep is broken and shallow.

Recommended checkups

  • Group B Strep (GBS) screening is scheduled around week 36 — confirm timing.

Jump to week

Textbook averages. Individual variation is wide and this is not medical advice — confirm with your OB.