I'm a second year vet student with a two-and-a-half year old and an eight-month old (born in March of my first year of vet school). Another girl in my class had her first baby during first year, second semester finals (he arrived a little early); this year a classmate had her second child in early November. One class member is currently pregnant with her second child and due this summer. Another girl joined our class this year after taking a year off to have her first child. It's doable, but it's not easy. Some things to consider:
You won't know until it's too late if you'll experience morning sickness. Staying home in bed is not an option; sitting through class can be challenging. I found labs were easier than lecture because I could move around...activity made me feel better.
Wearing a respirator in lab seemed like it was going to be a pain, but it ended up not being too bad. I had to yell through it to be heard, and it took my lab partners some time to be able to reliably understand me, but on the up side, I never smelled a thing!
There is the possibility of complications that could force you to take a medical leave of absence for a year, assuming your school even offers those.
It's critical that your spouse or partner be 100% supportive and willing to be a very hands-on parent. I'm tremendously fortunate to have family in the area to help too.
If your baby is born during the semester, there is no special "maternity leave," at least at CSU. The standard policy for excused absences applies: you can miss two hours per credit hour, which generally translates in two weeks off, max. However, with an infant, there's barely enough time in the day to keep up with current material; catching up on two weeks' worth would be, in my opinion, darn near insurmountable. (The two of us who had babies mid-semester were out 3-4 days). I also don't believe I could have returned and finished out the semester if it had been my first child.
I haven't been able to do as much club stuff as I would like, and I've had to pass on an elective because it was only offered at night. These activities and being home for bedtime are mutally-exclusive. Senior year is going to be very difficult when it comes to spending time at home. Again, having a supportive partner is key.
Finally, consider your time management skills and your tolerence for sleep-deprivation. Speaking of time management...gotta run! Let me know if you have specific questions and I'll reply when finals wrap up later in the week!