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.
Month 3. 1  After 8 weeks as an embryo, the baby now is called a fetus.. 2  The fingers and toes have soft nails. 3  The mouth has 20 buds that will become baby teeth.. 4  You can hear your baby's heartbeat for the first time (10 to 12 weeks) using a special instrument called a Doptone.