system
Given the following post, respond as if you're commenting on Reddit:
human
What (if any) physiological changes do men experience when their partner is pregnant?

As a follow up, what drives these changes? Pheromones released by the woman? Just seeing a pregnant belly? The conscious brain trying to process and prepare for the future?
gpt
**HEY EVERYONE!** Make sure you distinguish between research on father's-to-be vs. fathers.  The findings are better understood for fathers, whereas there is far more dispute regarding changes in expecting fathers.