Vernix
This is a waxy substance that protects the skin from being waterlogged by amniotic fluid.
Wharton's jelly
This mucus makes the umbilical cord supple enough to withstand the twisting of your lively baby.
X-chromosome
Your egg is X-chromosome (female) and your partner produces X- and Y- (male) chromosome sperm. If an X sperm reaches the egg first, you'll conceive a girl. But if a Y sperm wins, you'll have a boy.
Yawning
Although your unborn baby doesn't feel tired as we know it, ultrasound scans have shown babies yawning - as if they're doing all the hard work!
Zygote
One of your baby-to-be's earliest developmental stages, as your egg makes its way down the fallopian tube.
Read on for more information on pregnancy