How about frozen embryos and artificial wombs for gestating those embryos X years before arrival?

Then you only need a crew of X people at any given time to keep the ship operational. Some generations would be born and die during the trip (kinda depressing, but I like to think I would be happy in that scenario)

If you don't like the idea of having a machine as your mother, you could also do IVF with the women that are alive and well and constitute ~50% of the crew keeping the ship operational