“…Preterm delivery rates were reported by 40 studies ranging from 0.0 to 21.34% (Table 1 ) [ 28 , 29 , 31 – 35 , 37 , 39 – 42 , 46 , 47 , 49 , 51 , 52 , 54 – 56 , 59 , 60 , 62 , 63 , 65 – 67 , 69 , 70 , 72 , 73 , 76 , 77 , 79 – 82 , 84 , 88 , 89 ]. Twenty studies did not report the mean BMI [ 30 , 31 , 33 , 35 , 36 , 38 , 41 , 42 , 55 , 58 , 61 , 70 – 72 , 74 , 78 , 80 , 82 , 83 , 88 ] and only two studies did not report the prevalence of BMI categories [ 48 , 63 ]. Furthermore, regarding the methods of collecting GWG: eighteen studies measured the GWG [ 30 , 36 , 43 , 45 – 48 , 52 , 54 , 57 , 59 , 60 , 62 , 63 , 65 , ...…”