Conception and fetal development

Trophoblast

Becomes Placenta

Embryoblast

Becomes Embryo

Decidua Basalis

Forms Maternal portion of placenta

Embryo

• Day 15-18 weeks after conception

• Most critical time for development

Nagele’s rule

Subtract 3 months add 7 days = estimated due date (EDD)

Chorion

• Blends with Placenta

Amnion

Blends with umbilical cord = Can be peeled

Yolk Sac

• Plays a crucial role in providing nourishment and facilitating gas exchange until the placenta is fully established. The yolk sac also contributes to the formation of blood cells, stem cells, and reproductive cells

Wharton’s Jelly

• Surrounds vessels to prevent compassion

Placenta is complete by 12th week

Progesterone

Primary hormone necessary to maintain healthy pregnancy

Fetal circulatory system contains physiolgoic holes to mix oxygenated and deoxygenated blood since there is no gas exchange occurring

These holes usually close near term, if not left with murmurs or worse requiring surgery

at 40 weeks pulmonary branching is only 2/3 complete

Senses

Taste: 16 weeks

Sound: 24 weeks

Sight by 26 weeks

When did multiple births in US Escalate

During 80’s -90’s

Teratogens

Greatest effect during embryonic period: day 15-60