(Ivanhoe Newswire) -- Obese women who gain more weight than recommended during pregnancy are more likely to retain as much as 40 percent of that weight one year after they give birth, according to a Kaiser Permanente study.

"We found that nearly three quarters of obese women gain too much weight during pregnancy -- and the more weight they gain, the harder it is to lose," lead author Kim Vesco, M.D., M.P.H., at the Kaiser Permanente Center for Health Research, was quoted as saying. "This extra weight also increases the risk of . . . complications like diabetes, preeclampsia, bigger babies, C-sections, and birthing injuries."

The study defined excess weight as more than 15 pounds. Recently, the Institute of Medicine (IOM) lowered the upper limit for weight gain in obese pregnant women, suggesting they gain no more than 11-20 pounds.

Researchers studied 1,656 Oregon and Washington women enrolled in the Kaiser Permanente health plan whose body mass index was 30 or higher at the start of their pregnancies, and who gave birth between January 2000 and December 2005. The study looked at pregnancy weight gain and weight retained one year after delivery.

Compared to women who gained less than the recommended 15 pounds, women who gained more than 15 pounds were twice as likely to retain 10 excess pounds. Women who gained more than 35 pounds were nearly eight times more likely to retain at least 10 pounds. The study also found that younger women and first-time mothers were most likely to gain too much weight.

"We need to do a better job of helping obese women control weight gain during their pregnancies. Once the baby is born, it's much harder to change eating habits and start an exercise program," Victor Stevens, Ph.D., co-author and senior investigator at the Kaiser Permanente Center for Health Research, was quoted as saying. "If we can prevent the weight gain in the first place, moms and babies will be healthier in the long run."

Tips for Controlling Excess Weight Gain During Pregnancy:

• Every day eat 8 fruit and vegetable servings, 3 servings of low-fat dairy, 5 ounces of protein-rich foods, 6 servings of whole grains, and 3 teaspoons of healthy fat (e.g., olive or canola oil, nuts).

• Eat regular meals and small healthy snacks between meals.

• Reduce fat to less than 30 percent of calories.

• Reduce consumption of sweets and sweetened drinks.

• Keep a food diary to check for nutritional adequacy and portion management.

• Eat only 100 extra calories per day beyond what your calorie needs were before you became pregnant.

• Exercise 30 minutes on most days. If you aren't exercising, talk to your doctor about how to start an exercise program.