At 33 weeks pregnant, your baby is in the third trimester and growing rapidly. They look more like a full-term newborn every day, but there are still important finishing touches happening inside the womb.

Baby’s Growth & Size

• Weight: About 4.25-4.5 pounds (1.9-2.0 kg).

• Length: Around 17 inches (43-44 cm) from head to heel.

• Baby is gaining about ½ pound (225 g) per week now, mostly as fat to help regulate body temperature after birth.

Development & Features

• Brain: Still developing quickly- the folds (gyri and sulci) are deepening, giving the brain a more mature appearance.

• Lungs: Continuing to produce surfactant, but not fully ready; a baby born now may still need a little breathing support.

• Bones: Fully formed but still soft and pliable; skull bones are not yet fused to allow for passage through the birth canal.

• Muscles: Growing stronger, making kicks and rolls more powerful, though space is getting tight.

• Skin: Becoming less red and wrinkled as more fat builds up.

• Eyes & senses: Pupils now respond to light, and your baby can tell the difference between day and night through filtered light in the womb.

• Immune system: Still receiving antibodies from you through the placenta for protection after birth.

Movements

• Baby is active but has less room to move freely. You’ll feel more stretching, rolling, and shifting rather than big jabs.

• Regular movement is still important- kick counts help you track activity.

Vernix & Lanugo

• Vernix caseosa (the creamy protective coating) is getting thicker.

• Lanugo (fine body hair) is starting to shed but may remain in some areas.

Position

• Many babies begin settling into a head-down position now, though some are still breech or transverse. There’s still time for turning before birth.

Key Point: At 33 weeks, your baby is continuing to build fat, strengthen muscles, and refine vital systems like the brain and lungs. They look very much like a newborn but still need several more weeks to finish maturing.