I used to buy into the argument, "My body, my choice." It is true, you shoud have a right to do what you wish with your own body. For exampe, you can decide to put a lot of alcohol in your body every day. My question is, though, is this a good choice? With drinking large amounts of alcohol every day, there are repercussions. The alcolhol will over time destroy your liver, which is much needed for survival. Drinking large amounts of alcohol is known to often hurt others, as with drunk driving.
Choosing to kill your child also has repercussions. The weight of guilt over having killed your own baby doesn't go just go away over time, even though you might believe "my body, my choice." It gets buried deep and rots, just like that babies' body. It leads to depression and suicidal thoughts. Many who later have a baby find they are unable to properly bond with that child. Studies have shown that women who have had abortions have a greater risk for breast cancer. Abortion outright kills some women.
Also the problem with the argument "my body my choice" is that it is not really your body that we are talking about. It is a baby. It is a living human being that will be prevented from living out his or her destiny.
The decision to end another's life is so final, so irreversible. You can't take it back. Please consider more humane options if you don't want to have a baby. Not having sex makes sense if you don't want a child. If you are faced with an unwanted pregnancy, please consider adoption. Children are such a joy, you might even want to raise the child.