These are safeguards taken to prevent conception and a woman becoming pregnant when a male and female engage in sex unless a child is planned. Some of the numerous methods are more reliable or are more permanent than others are.
As modern birth control through medical intervention was unknown in Bible times, the Bible therefore neither condones nor condemns the practice. The only time that remotely resembles birth control was when God severely judged a person because he did not want his inheritance to be shared with his deceased brothers family as was the prevailing law at the time (Gen 38:6-10; Deut 25:5-10). Although Onan fulfilled this obligation to marry, he had a wrong motivation and when having sex withdrew so he would not father a child. It was this selfish motive to use Tamar for his pleasure without meeting his obligation, rather than the act of contraception that was judged.
Throughout the Bible, children are viewed as a gift from God, a heritage from the Lord – being barren had a cultural stigma (Gen 4:1, 30:23, 33:5; Ps 127:3-5; Lk 1:25). While it is a personal matter of heart and conviction for a couple if they have children or how many, abortion is not a viable option as this is the intentional terminating of a life which although still an embryo/fetus God views as murder (Ex 20:13). The female eggs and male sperm are God-given aspects of healthy bodies given for the purpose of bringing children into the world. From a Christian point of view contraception must prevent the fertilization of the egg by a sperm as individually they do not have the capability to reproduce yet they have the potential to develop into a person which is the normal outcome when they are united. Abortion is the termination of a new life (however small) and although considered legal in many countries is viewed in God's eyes as murder – the unlaw taking the life of another (Ex 20:13).