I've gotten blocked ears a few times and another preg friend told me it is a symptom and she gets it all the time.
My guess at an explanation is that we retain more fluid- some people get swollen ankles, others get swollen hands, I guess the ear canals are just a bit swollen or have more mucus like our noses and sinuses do, and so they get blocked more easily.

any one have any tips for unblocking them?