Clinical Drug Experience Knowledgebase

Does Metformin Improve Pregnancy Outcomes (Incidence of LGA (≥90% Birth Weight Centile) Babies, Onset of Maternal GDM, Hypertension, PET, Macrosomia, Shoulder Dystocia, Admission to SCBU) in Obese Non-diabetic Women?

Obesity in Pregnancy has been identified by the Confidential Enquiry into Maternal and Child Health [CEMACH] report (2007) as a major health risk to mother and baby:

35% of women who died were obese
30% of the mothers who had a stillbirth or a neonatal death were obese

Obesity increases the risk of miscarriages, GDM, pregnancy-induced hypertension/PET, Caesarean sections, deep venous thrombosis, puerperal sepsis and LGA babies. There is a 5-fold increase in costs of antenatal care. Results from various studies have concluded that limited or no weight gain during pregnancy in obese women results in more favourable pregnancy outcomes. By improving insulin sensitivity and enhancing GLP-1 release, metformin is associated with weight reduction by approximately 5.8% with no serious adverse events.

The aim of this study is to test the hypothesis that management of obese non-diabetic pregnant women with standardised life-style intervention (diet and physical activity) plus metformin will lead to improved maternal and perinatal outcomes compared with life-style intervention alone.

The study will also seek to determine whether metformin will improve body fat distribution as measured by bioimpedance during pregnancy with particular emphasis on metabolic active visceral fat.

Genetic studies will investigate whether patients with polymorphisms of the candidate fat gene, FTO gene, differ in their response to metformin and whether this is associated with favourable pregnancy outcomes.

This is a randomised, multicentre, double blind, placebo-controlled trial.Assuming power 90%, significance level 5% and 2-sided testing, we will recruit 425 subjects per arm of the trial.This will allow the detection of a difference in mean centile (z-score) of 0.21 standard deviations.

All women will undergo oral glucose tolerance testing at booking and at 28 wks; those found to have GDM at 28 weeks will commence home glucose monitoring and will receive metformin if glucose values are outside target range.

The primary outcome will be the birth weight centile (z score). Secondary outcomes include maternal and neonatal outcomes, body composition scores, patient satisfaction and infant development at 2 years. The relation between FTO gene variants and pregnancy outcomes will be examined. Parametric and non-parametric tests will be used as appropriate.

This is a multicentre trial to be undertaken in 7 centres in the UK over a period of 3 years in order to reach the required sample size. Mr Hassan Shehata, Clinical lead and Consultant Obstetrician and Gynecologist is the Chief Investigator of the trial and the trial will be centrally coordinated by Dr Jyoti Balani at Epsom and St Helier University Hospital. In the first phase of the research, we would be recruiting a total of 546 pregnant women into the trial. 200 women would be recruited at Epsom and St Helier Hospital, 200 women at kings college Hospital under the supervision of Professor Kypros Nicolaides and 146 at Royal Surrey County Hospital under the supervision of Dr Lesley Roberts.

Given the low cost of metformin and the potentially high impact on health for both mother and baby, we anticipate the study will show metformin to be highly cost-effective. We anticipate improved patient satisfaction scores in those taking metformin as they gain less weight and develop fewer complications. Improvements in the metabolic milieu during interuterine growth is expected to improve long term outcome for the infants of mothers treated with metformin.

Benefits to patients will be immediate from the time the project's findings are presented. Implementation into clinical practice is expected to greatly benefit the NHS.