I am pregnant and was never vaccinated against tetanus. If I get tetanus can it harm the baby?

Definitely. Tetanus can be fatal to you and your baby. Current recommendations are for pregnant women to receive the tdap vaccine to protect against tetanus diptheria, and whooping cough.
Yes. If you develop tetanus during pregnancy your own life would be in danger as would be the pregnancy. Two doses of vaccine 4 wks apart( at least 2wks before delivery) would not only protect you but provide the baby with some protection for several wks after birth. It is ok to get the vaccine while pregnant.
Yes Need Tdap. The answer is definitely yes.Are you sure you never had shots for Tetanus ever.The Primary Immunisation is given after birth starting at age 2 months.3 shots in first year2 months apart and one 15to18 months and again 4to6 years Boosters are given every 10 years.You need protection against Diptheria,Tetanus&Whooping cough.Discuss with your Doctor about getting immunused agaist all three with Tdap.