In Christianity, sex is meant to be kept within marriage. Hence, I guess you can say that Christians should not get pregnant before marriage. If the partner, whether guy/girl, is not a Christian, that person possibly may not share the same sentiments about sex/marriage. At the same time, being a Christian doesn’t automatically make a person holy or better than anyone. A Christian is someone who says he/she is sinful and acknowledges the need for God + the saving power of Christ.
Depends on you!