https://www.cdc.gov/mmwr/volumes/72/wr/mm7239a3.htm
Maternal vaccination can provide protection to your newborns from COVID during a time when they are unable to be vaccinated themselves. Here is maternal vaccination effectiveness against hospitalization during Omicron for newborns.
While children have lower risk from COVID than adults, infants have higher risks than older children, and for the youngest infants they can not be vaccinated against COVID. So it is imperative that expecting mothers get vaccinated.
I should note that there is also now a maternal vaccine against RSV that can provide protection to newborns. Like COVID, RSV can be especially severe in infants.