Women who have undergone bariatric (weight loss) surgery and go on to get pregnant are at an increased risk of giving birth prematurely or having small babies, new research suggests.

According to Swedish scientists, obesity is estimated to shorten a person's life by up to four years. This increases to up to 10 years if a person is morbidly obese. As a result, bariatric surgery, such as the insertion of a gastric band, has become increasingly popular in recent years.

Obesity is already known to be linked to poorer outcomes in pregnancy for both the mother and baby, so the scientists decided to investigate the link between bariatric surgery and perinatal outcomes (this refers to the time right before and after birth).

They analysed data from a number of patient registers in Sweden, including the Swedish Medical Birth Register, comparing women who had undergone weight loss surgery with women who had not between 1992 and 2009.

The scientists looked at a number of factors, including maternal age, BMI (body mass index), diabetes and smoking. Among women who went on to have babies after surgery, the average amount of time between the procedure and the birth was just over five years.

The scientists ended up focusing on 2,534 post-bariatric births and comparing them to almost 12,500 control births.

They found that almost 10% of the births in the surgery group were premature, compared to 6% in the control group. Women in the surgery group were also more likely to give birth to a baby who was small for their gestational age.

Babies who are small for their gestational age are at an increased risk of suffering health problems as a newborn, such as breathing problems, heart problems and and bleeding in the brain.

According to the team from the Karolinska Institute in Stockholm, women who become pregnant after undergoing bariatric surgery ‘should be regarded as a risk group and be counselled regarding the increased risk of preterm birth'.
They also called for more research into why these women are also at risk of having smaller babies.

Details of these findings are published in the British Medical Journal.

For more information on pregnancy, see our Pregnancy Clinic here