Placental growth, development and function

1. Big picture

The placenta is the temporary fetal-maternal organ that keeps the fetus alive. In an oral exam, the examiner wants you to explain three things clearly:

1. How it develops: implantation → trophoblast invasion → chorionic villi → uteroplacental circulation.
2. What it does: gas exchange, nutrient transfer, waste removal, endocrine production, immune protection.
3. What happens when it fails: fetal growth restriction, oligohydramnios, abnormal Doppler, preeclampsia, abruption, fetal distress, stillbirth.

Clinically, placental function is not assessed by “looking at the placenta” alone. It is assessed indirectly by:

**fetal growth + amniotic fluid + Doppler