A new study from the University of Southampton has shown that underweight and women with obesity are at a significantly higher risk of experiencing recurrent miscarriages compared with those of average weight.
The systematic review and meta-analysis, published in Scientific Reports, assess the associations between lifestyle factors and recurrent pregnancy loss (RPL). Studies that analysed RPL in the context of body mass index (BMI), smoking, alcohol and caffeine intake were included. The primary and secondary outcomes were odds of having RPL in the general population and odds of further miscarriage, respectively.
The analysis revealed that underweight (BMI, <18.5 kg/m2) and overweight (BMI, >25 kg/m2) women are at higher odds of RPL than the general population (OR, 1.20; 95% CI, 1.12-1.28 and OR, 1.21; 95% CI, 1.06-1.38, respectively).
In women with RPL, BMI >30 kg/m2 (obese) and >25 kg/m2 were associated with increased odds of further miscarriages (OR, 1.77; 95% CI, 1.25-2.50 and OR, 1.35; 95% CI, 1.07-1.72, respectively).
The researchers were unable to establish conclusively whether factors such as smoking and consumption of alcohol and caffeine have any impact or not due to inconsistencies in the results from a small number of studies and heterogeneity in women taking part in them.
First author, Dr Bonnie Ng, from the University of Southampton said, "Our study included sixteen studies and showed that being underweight or overweight significantly increases the risk of two consecutive pregnancy losses. For those with BMI greater than 25 and 30, their risk of suffering a further miscarriage increases by 20% and 70%, respectively."
The authors point out that the quality of the evidence provided by the included studies was low or very low.
