zygote - the union of a spermatozoon and an ovum, embryo - when a zygote attaches itself to the uterine wall, placenta - the organ that develops during pregnancy to provide oxygen and nutrients to the embryo, umbilical cord - connects the placenta to the embryo in order to transport oxygen and nutrients, amniotic sac - it is filled with fluid and grows around the embryo to protect it, foetus - when the embryo is 5 to 6 cm long at the start of the 2nd trimester, it is called this, birth - the muscles in the walls of the uterus contract and the cervix begins to dilate, 40 weeks/9 months - the general duration of a human pregnancy, 3rd trimester - the baby turns so the head is facing the opening of the uterus, contractions - the force that pushes the foetus through the cervix during childbirth,

Fertilization, pregnancy, and birth

由
嵌入

排行榜

视觉风格

选项

切换模板

恢复自动保存：？