Metformin in Obese Non-diabetic Pregnant Women (MOP)

Obesity is on the rise in all developed countries. Of particular concern is that more young people including children are being recognised as being overweight or obese. We know from a recent large national enquiry into all maternal and child deaths in the UK, known as CEMACH, that obesity is a major risk both for the mother and her child. When all deaths in women during pregnancy are analysed, obesity comes out as the most common risk factor. Babies of obese mothers are more than 3 times as likely to need admission to the Neonatal Intensive Care Unit.

Traditionally, obesity is treated by lifestyle measures encouraging healthy eating and increasing physical activity. Unfortunately these measures are often insufficient to produce significant improvements in weight. If obese women gain little or even no weight during pregnancy, the outcome of the pregnancy is known to be improved. This was shown in a very large study of more than 120, 000 obese women.

The drug metformin has been used for years in the treatment of diabetes and more recently for polycystic ovary syndrome (PCOS). Studies in pregnant PCOS women and women with diabetes in pregnancy have shown it to be safe and effective. Fortunately it is relatively cheap and taken as a tablet with meals.

Metformin has the great advantage of not causing weight gain and often leads to a small amount of weight loss. It works by improving the body's sensitivity to insulin which is important as resistance to insulin is common in obesity.

We have a lot of experience using metformin to treat women with diabetes in pregnancy where it is greatly beneficial. We now wish to examine its potential for obese women who do not have diabetes. We are hoping to show that it will benefit these women by causing less weight gain, less high blood pressure, and less diabetes. We anticipate babies will also have better birth weights, will be easier to deliver naturally, will not need to go to special care baby units and will be healthier.