| A | B |
|---|
| trimester | A period of about three months |
| ovum | A woman’s egg |
| ovulation | Once a month a woman’s egg is released from the ovaries |
| sperm | Male cell |
| conception | Sperm and ovum unite; also known as fertilization |
| zygote | Fertilized human egg; the zygote stage lasts from conception to two weeks |
| embryo | The developing baby from about the third week of pregnancy through the eighth week |
| fetus | The final stage of pregnancy from the ninth week until birth |
| prenatal development | All development that occurs between conception and birth |
| amniotic fluid | A fluid that cushions the baby against possible injury, allows the baby to move around easily, and regulates the baby’s temperature |
| amniotic sac | The sac that holds the amniotic fluid |
| umbilical cord | A flexible cord that contains blood vessels and connects the baby to the placenta |
| placenta | provides nutrients and blood to the fetus |
| blastocyst | A hollow ball of cells from the fertilized egg that implants itself into the uterus lining |
| lightening | late pregnancy when the fetal head begins to descend into the mother’s pelvis, resulting in a lessening of pressure on the diaphragm |
| quickening | To move and be felt moving in the womb |
| uterus | A hollow muscular organ in the pelvic cavity of the female, in which the embryo is nourished and develops before birth |
| lanugo | Soft prenatal hair, usually shed in the 7th to 8th month |
| vernix caseosa | Waxy or "cheesy" white substance found coating the skin of newborn humans |
