Sources of indoor pollution include. 1  Mold and pollen. 2  Tobacco smoke. 3  Household products and pesticides. 4  Gases such as radon and carbon monoxide. 5  Materials used in the building such as asbestos, formaldehyde and lead.
After conception, your baby begins a period of dramatic change known as the embryonic stage. This stage runs from the 5th through the 10th week of the first trimester of pregnancy. During this stage, the baby is called an embryo. Your babyâs penis or vagina is visible at the end of the embryonic period, but it's not yet possible to tell on an ultrasound if your baby is a girl or a boy. 2  Muscles and movement. 3  Muscles develop and the embryo begins to move.
All of the processes of embryo development are described by the term embryogenesis. The embryo is called a fetus after the completion of this stage of development. The stage of prenatal development that occurs from the end of the embryonic period until birth is called the fetal period.The most notable development during this stage is the dramatic change in size that takes place. This is the baby's final preparation for life outside the womb.hink of Steve and Jennifer's baby as spending the germinal period looking for a place to live. Now that she's found her place, she's ready to start organizing for the work she has ahead of her. This is the embryonic period of prenatal development.