Short answer
Yes, plain, cooked sweetcorn kernels are safe for pregnant or nursing dogs in moderation. They provide some fiber and can be a small, low-risk addition to her regular, balanced diet. The critical thing to remember is to never, ever give her the corn cob, as it's a common cause of intestinal blockage requiring surgery. Offer just a few kernels at a time, and if she has any digestive upset, stop and consult your own vet.
Sweetcorn kernels — Food safety facts
Safe to share · Dogs · full breakdown on the linked food page
Plain kernels are safe. The cob is not — it causes blockages and is a common surgery case.
The full verdict, portion guidance and serving notes are collected on the Sweetcorn kernels food facts page.