Several previous studies have suggested that maternal pre-pregnancy overweight/obesity was related to increased rates of both subtypes of PTB42,43, but sPTB alone was reported to be associated with obesity (BMI ≥ 30.0 kg/m2), whereas both overweight and obesity (BMI ≥ 25.0 kg/m2) were related to mPTB3,42. This evidence concerns the gene SPTB and obesity due to melanocortin 4 receptor deficiency.