Do multiple pregnancies present higher risks than singleton pregnancies?

Absotutely. Every risk in a singleton pregnancy is higher with twins. Risk of miscarriage, genetic abnormalities in a child, and even though small, the risk of one baby not surviving. Risks to mother of hypertension and diabetes are much higher. And the risk of early delivery is much higher. Even though twins generally do well, many twins do not. So it is always medically preferable to have a single pregnancy.
Yes. Multiple pregnancies carry higher risks of complications, including preterm birth, pre-eclampsia, fetal growth restriction, polyhydramnios (too much amniotic fluid), placental abruption, postpartum hemorrhage, cord accident, and cerebral palsy. Risk of miscarriage & congenital anomalies is also increased. If you're having multiples, be sure to practice healthy habits & follow up w/ your ob.