Obesity and overweight is increasing in prevalence worldwide, and is now considered a global epidemic. It has become a significant threat to health in all sectors of the population, including women of reproductive age. The World Health Organization estimates that more than 1 billion people are overweight, with 300 million meeting the criteria for obesity. In the USA 2% of pregnant women have a BMI<18.5 and more than 50% have a BMI>25. In Iran, women generally have a lower BMI and/or a smaller gestational weight gain than in developed countries.