At 21 weeks of pregnancy, a developing baby is about 27 cm long, weighs around 360 to 400 g, and is practicing movements, sucking, and breathing.

Most single pregnancies follow a curve where size rises from a few grams early on to about 3,000–3,600 grams by 40 weeks of gestation.

Fetal development spans the weeks when organs grow, senses sharpen, and a baby prepares for life outside the womb.

A lab-based blood test or scan can usually predict baby sex with high accuracy once enough fetal DNA or anatomy is visible.

Week-by-week fetal development shows how a tiny cluster of cells steadily becomes a fully formed newborn over about 40 weeks of pregnancy.

A handheld fetal Doppler is a small ultrasound gadget parents sometimes use at home to listen to a baby’s heartbeat between regular checkups.

Baby growth in the womb follows a steady week by week pattern from a cluster of cells to a newborn ready for life outside.

Home heartbeat monitors use ultrasound to pick up fetal heart sounds, but experts advise using them briefly and only under midwife or doctor guidance.

At 22 weeks, the baby usually weighs around 430–500 grams and measures about 27–28 cm, with fast changes in movement, senses, and organ maturity.

From conception to birth, a baby grows through clear stages that shape organs, senses, movement, and readiness for life outside the womb.