If you want to conceive a girl, then choosing the right sexual position is very important.

In order to increase your chance of conceiving a girl, you should have intercourse in a position that allows shallow penetration (for example missionary), as shallow penetration allows the sperm to be deposited further away from the egg.

Because female sperm are thought to be stronger than male sperm, they are more likely to be able to swim the greater distance to the womb than male sperm (which are weaker and less resilient than female sperm). So by using a shallow penetration position, and increasing the distance to the egg, male sperm are more likely to die before they complete the longer journey. Ideally this will leave only female sperm remaining, giving them a much better chance of fertilising the egg, giving you a baby girl.