i read about some information regarding to weight and sex of the baby. carrying baby boy tend to be heavier bcoz they need more energy than girl, so mother should gain weight more than carrying girls. it make sense that when baby boy is born they are usually 8lbs because they r bigger and stronger, ie heaiver. but girl tend to be lighter, small in build.
i was carring a boy and blow like a balloon, myself.i put on about 16kgs before he is born. and he is 3.3kgs.