How can your sim give birth to a female on sims 2?

It is random, however your can influence the chance to have a boy or girl via cheats.

For boys:

The Sims 2

Enter cheat mode:

type: CTRL + SHIFT + C

type: boolprop forceboys 100

For girls:

The Sims 2Enter cheat mode:

type: CTRL + SHIFT + C

type: boolprop forcegirls 100