Baby: Week 21

Important physical changes are occuring, as the bone marrow has taken over its lifelong function of manufacturing blood cells.

Human foetus 21 weeks from conception. Photo credit - Prof. Andrzej Skawina ph. D., MD. From the laboratory of Collegium Medicum of the Jagiellonian University in Kraków

You’re about 500g now, and measuring about 29cm from head to heel.

You now hear quite well, and listen to your mother’s heart beating, her stomach rumbling, and her conversations! She may be able to see you move in her belly.[1]

Important physical changes are occuring, as the bone marrow has taken over its lifelong function of manufacturing blood cells. Your lungs are developing the lower airways.[2]

This is the first week a baby could survive outside the womb, although chances of survival at this early age are only 15%.[3] Mothers should be aware of risk factors for premature birth: pre-eclampsia, abnormal placenta, very young or advanced maternal age, twins or other multiples, abortion in a previous pregnancy, preterm premature rupture of the membranes, and previous premature birth.[4]