T HREE STAGES OF P REGNANCY

P RENATAL DEVELOPMENT Prenatal development is the baby’s development during pregnancy 3 stages of prenatal development Germinal Embryonic Fetal Different developmental milestones at each stage

T HE G ERMINAL S TAGE Germinal is first stage Formation of the zygote, or fertilized egg Lasts about 2 weeks Includes cell division and Implantation Cell Division Zygote grows in the fallopian tube by cell division Single cell splits into two cells, then two cells multiply to four, and so on. After about 4 days the zygote reached the opening to the uterus.

T HE G ERMINAL S TAGE Implantation The lining of the uterus has thickened enough to provide a place for the zygote to attach itself and grow. Zygote implants in the lining and is covered by it. There is rapid growth, but the zygote is only the size of the head of a pin.

E MBRYONIC S TAGE Second stage of pregnancy Developing baby is called the embryo from third week through eighth week of pregnancy Embryo grows rapidly Important changes occur

E MBRYONIC S TAGE Organs and Body Systems Cells separate and develop into major systems Heart Lungs Bones Muscles 27 days after conception, the neural tube closes This becomes the brain and spinal cord. By the sixth week after conception, the brain and spine have connected and allow first movements.

E MBRYONIC S TAGE Amniotic Sac A sac filled with fluid, called amniotic fluid, forms around the embryo. Helps protect the baby from any bumps or falls the mother may have At this point embryo is about 1 inch long.

E MBRYONIC S TAGE Placenta and Umbilical cord Tissue called the placenta develops Rich in blood vessels and attached to the wall of the uterus Mother’s bloodstream carries food and oxygen to the placenta Placenta absorbs oxygen and nourishment and transmits it to the baby through the umbilical cord, which is connected to the baby. Umbilical cord takes carbon dioxide and other waste away from the baby. Placenta and cord provide everything a baby needs until birth.

F ETAL S TAGE Last and longest stage of development Begins around eighth or ninth week and lasts until birth Developing baby is called a fetus Buds for “baby” teeth appear. Vocal cord develops Digestive system and kidneys begin to function By end of third month, spontaneous movements are possible

F ETAL S TAGE Making Movements During fourth or fifth month, baby kicks and movements can be felt by mother. Movements become stronger as time passes Doctor’s usually asks when movements are felt to estimate age and project accurate due date.

F ETAL S TAGE Completing Development During last months, development continues to prepare fetus to live outside the mother Fetus gains weight rapidly Organs become ready to function without help from mother’s body Fat deposits are formed Fetus stores nutrients and builds immunity to diseases and infections

F ETAL S TAGE Staying Active Fetus can do several things Suck thumb Cough Sneeze Yawn Kick Hiccup Cry

F ETAL S TAGE Growing Bigger As fetus grows, so does amniotic fluid Uterus expands and abdomen grows In last months, there is no longer room so fetus curls up into fetal position Ready for Birth Common length of pregnancy is about 40 weeks, or 280 days, from the first day of the last menstrual cycle. By ninth month, fetus is fully developed Some babies are born a few weeks early or late Those born early survive due to advances in technology

A SSIGNMENT Create a mobile about the three stages of fetal development Include one picture for each stage List at least three things that happen in each stage List what weeks of pregnancy this occurs BE CREATIVE