You may have heard that some positions, such as your partner on top (missionary position), are better than others for getting pregnant. In fact, there's no evidence to back these theories up. Experts just haven't done the research yet.
What experts have done, though, is use scanning to show what's going on inside when you're doing the deed. The research looked at two positions: the missionary position and doggy style. (Doggy style being when you're on all fours, and your partner enters you from behind).
Common sense tells us that these positions allow for deep penetration. This means that they're more likely to place sperm right next to your cervix (the opening of your uterus).
The scans confirm that the tip of the penis reaches the areas between the cervix and vaginal walls in both of these positions. The missionary position allows the penis to reach the area at the front of the cervix. The rear entry position reaches the area at back of the cervix.
It's amazing what some experts spend their time doing, isn't it! Other positions, such as standing up, or woman on top, may be just as good for getting sperm right next to the cervix. We just don't know yet.