Table 2

Adjusted ORs (AORs) for maternal and neonatal outcomes according to maternal BMI for women in the cohort

≤18 kg/m2 (n=751)19–24 kg/m2 (n=7431)25–29 kg/m2 (n=3748)30–34 kg/m2 (n=1598)35–39 kg/m2 (n=737)≥40 kg/m2 (n=592)
Birth status
 Liveborn0.844 (0.455 to 1.748)1.001.496 (0.984 to 2.342)0.837 (0.525 to 1.396)1.016 (0.517 to 2.300)1.081 (0.506 to 2.805)
 Stillborn1.185 (0.572 to 2.197)1.000.669 (0.427 to 1.016)1.195 (0.716 to 1.906)0.985 (0.435 to 1.935)0.925 (0.356 to 1.977)
Birth type
 Spontaneous vaginal1.162 (0.927 to 1.445)1.001.13 (1.002 to 1.274)0.781 (0.646 to 0.939)0.642 (0.473 to 0.855)0.996 (0.742 to 1.315)
 Caesarean0.678 (0.548 to 0.832)1.001.296 (1.180 to 1.422)1.822 (1.612 to 2.057)2.601 (2.210 to 3.058)2.703 (2.257 to 3.232)
 Instrumental vaginal1.215 (1.028 to 1.441)1.000.772 (0.710 to 0.840)0.664 (0.592 to 0.745)0.498 (0.424 to 0.584)0.411 (0.343 to 0.490)
Apgar score
 Low 5 min Apgar score ≤60.610 (0.351 to 0.985)1.001.130 (0.915 to 1.389)1.743 (1.356 to 2.221)1.552 (1.075 to 2.183)1.799 (1.225 to 2.567)
Infant birth weight
 Macrosomia0.534 (0.370 to 0.746)1.001.529 (1.356 to 1.722)1.720 (1.471 to 2.007)1.527 (1.225 to 1.889)1.935 (1.541 to 2.413)
 LBW <2500 g1.706 (1.356 to 2.128)1.000.852 (0.734 to 0.986)1.163 (0.966 to 1.394)0.917 (0.690 to 1.198)0.799 (0.575 to 1.086)
 SGA1.804 (1.491 to 2.174)1.000.867 (0.765 to 0.982)0.882 (0.740 to 1.047)0.817 (0.627 to 1.049)0.752 (0.555 to 0.999)
 LGA0.441 (0.271 to 0.676)1.001.596 (1.389 to 1.832)2.084 (1.754 to 2.471)2.187 (1.739 to 2.729)2.743 (2.165 to 3.449)
Maternal blood loss
 Haemorrhage ≥500 mL0.986 (0.787 to 1.224)1.001.039 (0.928 to 1.164)1.340 (1.154 to 1.551)1.528 (1.247 to 1.862)1.349 (1.066 to 1.693)
Peristatus
 Third-degree/fourth-degree tear*1.250 (0.876 to 1.744)1.001.208 (0.975 to 1.490)0.879 (0.604 to 1.243)0.869 (0.454 to 1.513)0.777 (0.364 to 1.453)
 Episiotomy*1.111 (0.836 to 1.458)1.000.980 (0.828 to 1.156)0.763 (0.577 to 0.994)0.698 (0.429 to 1.077)0.693 (0.409 to 1.105)
Obstetric complications
 GDM0.722 (0.338 to 1.356)1.002.171 (1.668 to 2.828)3.529 (2.587 to 4.785)4.991 (3.424 to 7.161)7.817 (5.415 to 11.154)
 Hypertensive disorders1.282 (0.595 to 2.437)1.001.953 (1.419 to 2.686)3.415 (2.392 to 4.842)6.077 (4.103 to 8.890)8.947 (6.110 to 12.990)
Labour complications
 Shoulder dystocia0.148 (0.008 to 0.671)1.001.076 (0.729 to 1.566)1.241 (0.742 to 1.988)1.624 (0.853 to 2.858)1.702 (0.845 to 3.112)
 VBAC0.661 (0.107 to 2.191)1.000.544 (0.254 to 1.065)1.035 (0.443 to 2.144)NA0.582 (0.093 to 1.975)
Neonatal outcomes
 Hypoglycaemia1.101 (0.571 to 1.935)1.001.414 (1.042 to 1.909)1.740 (1.178 to 2.519)2.415 (1.484 to 3.770)2.892 (1.753 to 4.569)
 Birth trauma1.192 (0.598 to 2.150)1.001.232 (0.873 to 1.721)1.428 (0.900 to 2.189)1.147 (0.534 to 2.171)1.943 (0.998 to 3.461)
 Respiratory distress0.838 (0.461 to 1.402)1.000.817 (0.620 to 1.068)1.368 (0.994 to 1.855)2.004 (1.364 to 2.867)1.566 (0.976 to 2.398)
  • Reference group is BMI 19–24 kg/m2. ORs and 95% CIs from logistic models adjusted for parity, maternal age, country of birth and smoking. Significant results are bolded.

  • *Women who had a caesarean for the second pregnancy excluded.

  • BMI, body mass index; GDM, gestational diabetes mellitus; LBW, low birth weight; LGA, large for gestational age; NA, not applicable; SGA, small for gestational age; VBAC, vaginal birth after caesarean.