Most women get a lot of flack for their pregnancy weight gain, but a recent study published in Women and Birth suggests that women who gain 50, 60, even 70+ baby pounds don’t realize they’re at an unhealthy weight.

Researchers at the University of Adelaide studied 442 moms-to-be and found that more than 70 percent of women who are overweight or obese during pregnancy underestimate their weight, and they’re also more likely to gain excess pounds than those who correctly ID their body mass index (BMI).

What’s more, around half of women gain too much weight during pregnancy, according to one previous Obstetric Medicine study, and about half of those women don’t consider the extra pounds to be problematic.

All of these stats are cause for concern when you consider that excess weight gain puts women at risk for a slew of health problems including gestational diabetes, high blood pressure, and potentially fatal preeclampsia.

Meanwhile, children of women who gained too much weight during pregnancy are more than four times more likely to be overweight at age 3 than those whose mothers gained a healthy amount, according to research from Harvard Medical School.

Many women feel pregnancy is the one time of their life they can eat whatever they want and gain weight, says lead researcher Zhixian Sui, a PhD candidate at the University of Adelaide. And since they don’t realize the consequences of gaining too much weight—or how much weight is too much, for that matter—it's no surprise that they'd go up too many sizes.

So what is the magic weight-gain number when you’re eating for two? While various factors play a role, the Institute of Medicine’s current guidelines say that women who are at a normal pre-pregnancy weight (BMI of 18.5 to 24.9) should gain between 25 and 35 pounds during pregnancy. (Don’t know your body mass index? Use our BMI calculator to find yours!)

The breakdown: a few pounds in the first few months of pregnancy and about four pounds a month during the second and third trimesters. That might mean eating (get this!) only 300-ish extra calories per day.