If you ask me, I think it is just a perfect little phrase that's perfectly timed.
How else is a pregnant woman supposed to justify that humongous hunger pang she feels every so often? Because trust me, no one (who has not had a bun in the oven) can ever comprehend this pregnancy induced physical/emotional/mental state.
You just need that Extra Large Fries, right now. Who cares if its 2 AM?
It is so easy for experts and doctors to tell a pregnant woman that all she needs is few hundred more calories per day. And that her growing belly is actually a baby and not more room in her stomach to process ALL that extra food she wants to eat.
In my last trimester , I craved for chocolates and found myself heading to the refrigerator each time I woke up to go to the bathroom. And that was like at least 10 times every night. Well... apparently the baby did not need all that extra chocolate and I really stretched out. :(
So please, listen to your doctor but once in a while, definitely 'Eat for two'!