“A twin pregnancy can only be confirmed through prenatal ultrasound. It’s not possible to definitively diagnose a twin gestation from hCG levels, as these can vary based on the gestational age of the pregnancy as well as from one person to the next. Prenatal ultrasound, on the other hand, can identify the number of gestational sacs, fetal poles, and whether there is fetal heart activity within one or both fetuses,” opines Sagaser.