Your "expectant" voice

Esophageal reflux: Late in pregnancy, women may notice some heartburn. This may mean that acids from the stomach are backing up the esophagus. If they spill over onto the larynx, they can harm vocal tissues, usually resulting in hoarseness. The reflux is often due to lying down soon after eating, over-eating, or eating fatty or acidic foods and/or drinking carbonated fluids.

Baby pressure:
A big, near-term belly may also hinder the amount of air you can breathe in for voicing. Try not to speak at the end of your breath. Instead, opt for short sentences and more frequent breaths.