The worldwide prevalence of obesity has risen over the past few decades and women are currently more likely than ever to enter pregnancy obese. Pre-pregnancy obesity and excessive gestational weight gain increase miscarriage rates and obstetric and neonatal complications, which result in a lower healthy live birth rate. In addition to its negative consequences for the mother, obesity has been shown to be an important risk factor for chronic illnesses, such as cardiovascular disease, metabolic syndrome and type 2 diabetes in the adolescence and adulthood of the offspring. Moreover, maternal obesity causes psychological problems, physical disabilities and higher healthcare costs. Fetal programming of metabolic function induced by obesity, through physiological and/or epigenetic mechanisms, may have an intergenerational effect and could, thus, perpetuate obesity in the next generation. In order to break this vicious circle and avoid serious short- and long-term negative outcomes for both mothers and fetuses, the prevention and adequate management of obesity and gestational weight gain are essential.