I had a flea problem earlier on in pregnancy. Fleas everywhere! I'd been using a flea treatment before, once a month, before we got super fleas that were immune to it.
Switched to advocate on the vets advice, and got a treatment for the house too. He said not to be in the house when it was sprayed, but I would be fine applying the neck drops as long as I followed normal hygiene practices, washing my hands after application and for a couple of days after touching the cat.
Just wear some gloves if you want to be extra cautious.