In 2008, an estimated 500,000,000 people were obese globally, which could result in a 2-4 year shorter life span, which increases to 8-10 years in those morbidly obese. Obesity is also a risk factor for adverse pregnancy and perinatal outcomes (relating to the time immediately before and after birth).
Weight reduction is imperative to improve maternal health and bariatric surgery (the branch of medicine that deals with the causes, prevention, and treatment of obesity) is currently the most effective method. Its use has increased rapidly since the 1990s.
A paper in BMJ says that women with a history of obesity surgery are at increased risk of giving birth to preterm or small-for-gestational age babies and should be regarded as an at-risk group.