Multiple pregnancy

1. Big picture

Multiple pregnancy means more than one fetus in the uterus, most commonly twins. For the final exam, the examiner wants you to think in one central sentence:

Multiple pregnancy is high-risk because preterm birth is common, and chorionicity determines fetal risk and surveillance.

The practical clinical approach is:

Confirm multiple pregnancy → determine chorionicity and amnionicity early → screen for anomalies and growth discordance → prevent/detect preterm birth → monitor for twin-specific complications → plan safe delivery.

The most important exam idea is that twins are not all the same. A dichorionic diamniotic twin pregnancy behaves very differently from a monochorionic monoamniotic pregnancy, because monochorionic twins share one placenta and therefore can develop severe vascular complications such as twin-to-twin transfusion syndrome (TTTS).

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