Everyone is different.

I eat whatever I feel like eating whenever I feel like eating it (pregnant or not) and gained 25kg in pregnancy #1, 20kg in #2 and 15kg so far in #3 (5 weeks to go). The weight discrepancy with the first two was just from my starting weight - 48kg the first time and 55kg the second - I ended up at much the same weight. 48kg for me puts me in the 'severely underweight' category so my body knew what to do.

You'd be insane to actively try and LIMIT your weight gain IMHO, if you feel hungry, eat!