Abortion is the medical practice of forcibly removing a foetus from the womb before it gains life, essentially cutting a pregnancy short. It is, to say the least, a controversial issue, and is regarded by some as a form of murder. Abortion is allowed by law in many Western nations (including nominally Christian nations such as the UK) within certain limits.
People who believe that abortion is acceptable within limits are described as "Pro-Choice" - choice in this case referring to the right to choose whether or not to have an abortion. Those who believe that abortion is unacceptable are described as "Pro-Life." Religious belief and a Pro-Life attitude commonly go together, but one by no means implies the other.
In modern times abortion is a surgical procedure, but the ancients had their forms of abortion as well. In ancient Greece, for example, the practice was to have the pregnant woman drink a poison that would force her to have a miscarriage.