Christianity has a complicated relationship with contraception. Like most religions with roots in the ancient world, Christianity has a generally pro-natalist position, which means that fertility and having children is valued highly. This makes sense given how precarious life could be in the ancient world. Over time, though, support for birth control and family planning has increased and come to play a larger role in the lives of Christians.
Early Christianity was generally opposed to contraception, not so much because birth control itself was abhorred but because abortion was. Early Christians made very little room for permitting abortions, but in the ancient world the various drugs used to block conception were similar to those used to induce abortions. Because the line separating abortion and contraception was so indistinct, it appears that Christians decided to play it safe and reject both.
Because people generally wanted more children, not fewer, the demand for contraceptive drugs and devices wasnt as high in the ancient world as it is today. Contraceptives certainly existed, but they werent used so often in family settings. Instead, they appear to have been more common with prostitutes and adultery in order to prevent the consequences of illicit sex from occurring. The association of contraception with illicit sex inclined many Christians to oppose contraceptives as well.
Another major context in which contraception occurred was several Christian heresies. Many Gnostics opposed procreation. Manicheans taught that procreating meant imitating the actions of humanitys satanic ancestor. In the Middle Ages, the Cathars encouraged people not to have children. The avoidance of procreation thus became associated in the Christian community with heretical religious beliefs, making it more difficult for people to choose to use them legitimately.
Strong advocacy of birth control didnt really take off until the 19th century, but not on the basis of Christian theological arguments. On the contrary, most Christians were hostile to efforts to educate people about birth control and distribute birth control devices. Even at this late stage, the preference for procreation over contraception was still very strong, though the scriptural and theological arguments in defense of it were more implicit and assumed.
It wasnt until the 20th century that support for family planning and contraception became respectable and common among theologians and in Christian communities. Roman Catholics resisted, however, and constructed stronger defenses of the anti-contraceptive position based upon natural law rather than simply scripture and tradition. Protestant churches continued to liberalize through the century until the use of contraceptives became a non-issue for most.
In recent years, conservative Protestants appear to have started moving closer to the Catholic (and Orthodox) view that contraception should be more tightly regulated than it has been. An increasing number of conservative Christians, whatever their denomination, are arguing that freely available birth control only encourages sexual license, promotes hedonism, and alienates people from Gods intentions with the sexual and procreative processes.

