I wouldn't name it a problem, but since I started playing Sims 2 again (it's been a year already) and especially since I started playing a Medieval Challenge where my sims have to have lots of children, I noticed that females give birth to more girls than boys.
So ... here are the facts (babies born in each family):

Family 1
3 girls
1 boy

Family 2
3 girls
2 boys

Family 3
3 girls
2 boys

Family 4
4 girls
2 boys

Family 5
6 girls
2 boys

Family 6
4 girls
0 boys

Family 7
3 girl
2 boys

Not a single family where boys are more than girls XD (and those are just the families that I studied in the past few months)

I remember reading somewhere that what a pregnant sims eats doesn't influence the gender of the baby and that the baby's gender is decided when it is born, but still ... I find it a little disturbing >.> (not that it affects my game too much, because playing this challenge I have to kill many of the women >.> ).

So, I was curious ... is it just me, or it happened to someone else too?How did you deal with it?Have you found a way to trick your game?

Happened to me too sometimes, like just yesterday I was playing a house who had seven girls before having a boy.

My sims also prefer to have girls

I have heard that it may help to save the game before birth and if you don't like the gender of the baby, you exit without saving the game and start anew, the baby should have the opposite gender. Don't know if it's true, though, I have never tried it myself.

Didn't we just have a My Sims Have Too Many Boys thread?

We did indeed: http://www.modthesims.info/showthread.php?t=463539

Because all the stuff about randomization has already been said in the earlier thread, I'm going to lock this one and encourage anyone who wants to continue the discussion to read through the earlier thread and post any questions or comments there.