Well, it depends mainly upon whether dad has spent the most time with the child.  The bench in king county is very professional i would not worry about being discriminated against it is unlikely although there are those who I respect who will directly contradict me on this.

If she has been breastfeeding or is breastfeeding now, she has an advantage.  do you have breasts?  Are you like ms. garrison from southpark?   hah. :) just joking.   if so then i would say you have leveled nature's playing field.

in the 1970's washington state repealed the "tender years" doctrine in the custody law, which held that during the those years 1-5 when the child was very young, there was a presumption that custody would be granted to the mother. again: the law has been repealed.