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Table 2 Pregnancy, labour and delivery characteristics of women in each BMI group

From: Effect of Body Mass Index on pregnancy outcomes in nulliparous women delivering singleton babies

Characteristics Underweight
BMI < 20
n = 2842
Normal
BMI = 20–24.9
n = 14076
Overweight
BMI = 25–29.9
n = 5308
Obese
BMI = 30–34.9
n = 1858
Morbidly Obese
BMI > 35
n = 157
Pre-eclampsia* 82(3.3%) 572(5.0%) 313(8.1%) 181(14.7%) 29(28.2%)
Gestational hypertension* 374(13.6%) 2662(19.7%) 1422(28.5%) 624(37.2%) 54(42.2%)
Abruptio placentae 12(0.4%) 83(0.6%) 31(0.6%) 13(0.7%) 3(1.9%)*
Placenta praevia 10(0.4%) 25(0.2%) 11(0.2%) 3(0.2%) 0(0%)
Induced labour* 683(24.0%) 3832(27.2%) 1771(33.4%) 796(42.8%) 77(49.0%)
Instrumental delivery 773(27.2%) 4040(28.7%) 1499(28.2%) 465(25.0%) 38(24.2%)
Total C-Section* 320(11.3%) 2305(16.4%) 1279(24.1%) 573(30.8%) 67(42.7%)
Elective C-section 73(2.6%) 487(3.5%) 221(4.2%) 88(4.7%)* 16(10.2%)*
Emergency CS* 247(8.7%) 1818(12.9%) 1058(19.9%) 488(26.3%) 51(32.5%)
Mean blood loss (mls)* 254.5 (6.9) 290.4 (5.7) 333.6(8.5) 400.5(7.2) 456.4(25.7)
Postpartum haemorrhage* 192(6.8%) 1356(9.5%) 708(13.3%) 369(19.9%) 37(23.6%)
Preterm delivery (< 37 weeks) 345(12.1%)* 1537(10.9%) 573(10.8%) 243(13.1%)* 32(20.4%)*
Preterm delivery (< 33 weeks) 58(2.0%) 331(2.4%) 122(2.3%) 77(4.1%)* 10(6.4%)*
Spontaneous preterm(< 37 wks) 244(8.5%)* 964(6.8%) 325(6.1%) 124(6.6%) 12(7.6%)*
Post term delivery (> 41 weeks) 108(3.8%)* 773(5.5%) 350 (6.6%)* 136(7.3%)* 7(4.5%)
Stillbirth 22(0.8%) 131(0.9%) 57(1.1%) 35(1.9%)* 4(2.5%)*
Birth weight < 2500 g 269(9.5%)* 980(7.0%) 327(6.2%) 142(7.6%) 19(12.1%)*
Birth weight > 4000 g* 100(3.5%) 1072(7.6%) 564(10.6%) 255(13.7%) 25(15.9%)
  1. Values expressed as number (per cent) or mean (Std. dev.)
  2. *P value less than 0.05