Baby developing inside you
over the weeks and months
Weeks, Months and Trimesters Guides
Week Twenty One: Nourishment evolves
|You are 21 weeks pregnant. (fetal age 19 weeks) |
Your baby's bone marrow has started making blood cells, a job done by the liver and spleen until this point. The placenta has provided nearly all of your baby's nourishment, now your baby will begin to absorb small amounts of sugar from swallowed amniotic fluid.
Based on the size of baby's head, which is about 2 inches (5cm), the date of birth can be determined to within one week. The fetus is steadily gaining fat and has grown a whitish coat of a slick, fatty substance to protect skin in amniotic fluid and to ease delivery.
In girls, the vagina is formed and the ovaries already contain over six million eggs which will be reduced to about 400 by the time of puberty. For boys, the testes begin to descend from the abdomen this week. (Boys don't produce sperm until puberty).
The baby can hear and recognize the mother's voice, and may respond to some types of music.
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