Why missionary works.
If both male and female have excellent reproductive health, the chances of conceiving are 25% at best. However, having intercourse in the missionary position can help. In missionary, the man is on top of the woman who lays flat on the bed. Missionary gets the penis to the front of the cervix, improving the chances of conception.
Letting physics do the work
Another reason missionary is often successful could be gravity. Although sperm swims in any condition, laying down can possibly improve the chances of reaching the egg. Sperm moves quickly, so a standing position may reduce the chances of conceiving. Which is why some people believe women should continue lying down after sex for a few minutes but there is not sufficient evidence to say this works.
An obvious position with great results
Getting behind can get couples ahead in conceiving. Having the man enter from behind, commonly called doggystyle, gets the penis closer to the cervix than most positions. The position has the woman on her hands and knees or laying down on pillows for better comfort. Entering from behind can cause some discomfort to the woman, so the couple should work together for a relaxing experience.
Why the position works best
Entering from behind places the ejaculate at the back of the cervix. This greatly improves the chances of sperm traveling to the egg. For a man with motility issues, the position may be very useful. An MRI completed on sexual intercourse showed an improved angle of the penis at this position.
Get close with your partner
Researchers have few studies on the best positions for pregnancy. Factors holding more weight include reproductive health, sperm and egg quality, and even age. Nevertheless, choose a position that gets the penis as close to the cervix as possible so the sperm gets a better chance to reach and fertilize an egg. More importantly, the stress of trying to get pregnant during every tryst can weigh on both parties. For couples still unsure, have a candid convo with an OB/GYN for safe yet effective sex practices.