Blue whales are the largest animal on Earth, weighing in at 200 tons — and they give birth to healthy offspring that weigh around 3 tons.

Those newborns gain about 200 pounds a day for the first year, feeding only on mother's milk.

But for these whales, such surprising numbers are just what are needed to live long and healthy lives.

We humans, however, don't respond so well to weighing a lot and then getting pregnant.

For example, a new study reveals that boys whose mothers were obese when they became pregnant are at an increased risk for developing behavior problems by the time they are 9 to 11 years old. And the heavier Mom is when she becomes pregnant, the greater the risk.

That's because obesity during pregnancy creates inflammation and causes metabolic changes that might affect gene expression and alter a fetus's developing brain, damaging your child's future.

So, if you're overweight and planning to become pregnant, now's the time to shed those pounds.

Aim to lose four pounds a month; reduce your calorie intake by around 500 calories daily and increase your physical activity by at least 300 calories a day (walking 10,000 steps daily will more than do that).

A year from now, if you become pregnant, your child-to-be will have a great start on a healthier and happier life.