The fetus is indeed a human being. This is referred to many times in the Bible. Whilst abortion specifically is not mentioned, there are many references to the 'fetus' and its importance as a single entity.
Exodus 21:22-25; 22 “If men struggle with each other and strike a woman with child so that she gives birth prematurely, yet there is no injury, he shall surely be fined as the woman’s husband may demand of him, and he shall pay as the judges decide. 23 But if there is any further injury, then you shall appoint as a penalty life for life, 24 eye for eye, tooth for tooth, hand for hand, foot for foot, 25 burn for burn, wound for wound, bruise for bruise.”
Any man who should lay a hand on a pregnant woman so that she should give birth prematurely and injur the child can be punished as though they took the life of an adult.