Table 3.
Details of associations supported by highly suggestive evidence in meta-analyses of cohort studies on obesity and risk of obstetric and gynaecological morbidity. Outcomes are incidences unless stated otherwise. All statistical tests were two sided.
| Exposure | Outcome | No of studies | Sample size (cases/cohort) | RR (95% CI) of largest study | Random effects summary RR (95% CI)* | Random P value† | 95% prediction interval | 10% credibility RR (95% CI)* | Egger’s P‡ | I2 (%) | Excess significance§ | |
|---|---|---|---|---|---|---|---|---|---|---|---|---|
| O/E | P value | |||||||||||
| Assisted reproduction | ||||||||||||
| BMI >25 v <25 | Miscarriage rate | 20 | 3651/17 797 | 1.35 (1.20 to 1.53) | 1.31 (1.18 to 1.45) | 1.6−7 | 0.97 to 1.77 | 1.18 (1.05 to 1.33) | 1.00 | 46 | 8/8.0 | 1.00 |
| Gynaecological oncology | ||||||||||||
| WG per 5 kg increase | Endometrial cancer | 7 | 2806/460 901 | 1.17 (1.12 to 1.22) | 1.16 (1.12 to 1.20) | 3.7−18 | 1.06 to 1.27 | 1.13 (1.05 to 1.22) | 0.95 | 47 | 6/2.8 | 0.02 |
| Weight per 5 kg | Endometrial cancer | 7 | 1778/342 382 | 1.11 (1.08 to 1.15) | 1.17 (1.13 to 1.22) | 7.7−15 | 1.04 to 1.31 | 1.15 (1.06 to 1.25) | 0.29 | 62 | 6/1.0 | <0.01 |
| BMI iya per 5 kg/m2 | Endometrial cancer | 9 | 4345/631 915 | 1.23 (1.11 to 1.35) | 1.45 (1.28 to 1.64) | 1.9−9 | 0.98 to 2.15 | 1.33 (1.14 to 1.55) | 0.41 | 75 | 8/5.2 | 0.09 |
| BMI per 5 kg/m2 | Endometrial cancer | 28 | 22 320/6 445 255 | 1.65 (1.60 to 1.71) | 1.54 (1.47 to 1.61) | <1−100 | 1.26 to 1.89 | 1.41 (1.26 to 1.57) | 0.35 | 81 | 26/25.5 | 1.00 |
| BMI >30 v <25 | Endometrial cancer | 6 | 4327/1 485 506 | 2.73 (2.48 to 2.99) | 3.10 (2.63 to 3.65) | <1−100 | 1.92 to 5.00 | 2.99 (1.49 to 6.02) | 0.24 | 66 | 6/6.0 | 1.00 |
| WC per 10 cm | Endometrial cancer | 4 | 1524/315,770 | 1.28 (1.19 to 1.37) | 1.27 (1.17 to 1.39) | 7.3−8 | 0.88 to 1.85 | 1.20 (1.03 to 1.38) | 0.59 | 70 | 3/2.9 | 1.00 |
| BMI per 5 kg/m2 | Endometrial cancer, PoMP | 6 | 10 075/2 558 935 | 1.51 (1.45 to 1.58) | 1.60 (1.40 to 1.83) | 1.4−11 | 1.01 to 2.53 | 1.52 (1.16 to 1.98) | 0.88 | 89 | 6/5.0 | 0.60 |
| BMI per 5 kg/m2 | Endometrial cancer, type I | 3 | 7125/1 102 927 | 1.58 (1.53 to 1.62) | 1.75 (1.51 to 2.03) | 1.8−13 | 0.30 to 10.24 | 1.71 (1.06 to 2.77) | 0.26 | 82 | 3/2.9 | 1.00 |
| BMI per 5 kg/m2 | Endometrial cancer, type II | 3 | 1059/1 102 927 | 1.35 (1.25 to 1.46) | 1.59 (1.29 to 1.78) | 5.7−7 | 0.24 to 9.67 | 1.47 (1.03 to 2.08) | 0.52 | 76 | 3/1.5 | 0.25 |
| Obstetric, fetal | ||||||||||||
| BMI 25-30 v <25 | Apgar score <7 at 1 minute | 3 | 14 953/215 524 | 1.13 (1.09 to 1.17) | 1.14 (1.09 to 1.18) | 1.0−10 | 0.84 to 1.54 | 1.12 (1.01 to 1.24) | 0.79 | 8 | 2/2.5 | NA |
| BMI 30-40 v <25 | Apgar score <7 at 5 minutes | 8 | 4050/340 894 | 1.26 (1.16 to 1.36) | 1.40 (1.27 to 1.54) | 2.6−11 | 1.12 to 1.75 | 1.34 (1.12 to 1.61) | 0.04 | 34 | 6/5.6 | 1.00 |
| BMI >40 v <25 | Apgar score <7 at 5 minutes | 6 | 3015/290 134 | 1.70 (1.46 to 1.98) | 1.66 (1.36 to 2.02) | 7.5−7 | 0.91 to 3.02 | 1.22 (0.96 to 1.56) | 0.67 | 67 | 4/5.9 | NA |
| BMI 25-30 v <25 | LGA >90th centile | 18 | 92 234/1 041 119 | 1.54 (1.50 to 1.57) | 1.57 (1.47 to 1.67) | <1−100 | 1.25 to 1.97 | 1.34 (1.19 to 1.52) | 0.73 | 89 | 16/17.4 | NA |
| BMI >30 v <25 | LGA >90th centile | 19 | 88 791/969 294 | 1.95 (1.90 to 1.99) | 2.11 (1.97 to 2.27) | <1−100 | 1.62 to 2.75 | 1.68 (1.35 to 2.08) | 0.34 | 90 | 17/9.0 | NA |
| BMI >40 v 30-35 | LGA >90th centile | 7 | 32 377/229 817 | 1.30 (1.26 to 1.35) | 1.36 (1.29 to 1.45) | 6.1−26 | 1.17 to 1.59 | 1.22 (1.03 to 1.45) | 0.93 | 68 | 4/5.0 | NA |
| BMI 25-30 <25 | Macrosomia >4000 g | 19 | 93 168/1 049 501 | 1.54 (1.50 to 1.57) | 1.54 (1.45 to 1.64) | <1−100 | 1.22 to 1.95 | 1.32 (1.18 to 1.47) | 0.91 | 89 | 17/18.4 | NA |
| BMI >30 v <25 | Macrosomia >4000 g | 20 | 89 849/977 613 | 1.95 (1.90 to 1.99) | 2.08 (1.94 to 2.23) | <1−100 | 1.61 to 2.70 | 1.68 (1.36 to 2.07) | 0.40 | 90 | 18/20.0 | NA |
| BMI >30 v <25 | Macrosomia >4500 g | 7 | 2405/154 197 | 1.94 (1.72 to 2.18) | 3.59 (2.53 to 5.09) | 7.9−13 | 1.23 to 10.52 | 2.89 (1.48 to 5.62) | 0.18 | 89 | 7/4.9 | 0.11 |
| BMI 25-30 v <25 | SGA <10th centile | 14 | 71 232/774 816 | 0.79 (0.77 to 0.81) | 0.80 (0.73 to 0.87) | 2.5−7 | 0.61 to 1.05 | 0.87 (0.78 to 0.96) | 0.50 | 88 | 8/9.1 | NA |
| BMI per 5kg/m2 | Stillbirth >20/28 weeks’ gestation | 18 | 16 274/3 288 688 | 1.14 (1.11 to 1.16) | 1.24 (1.18 to 1.30) | 1.4−18 | 1.03 to 1.48 | 1.12 (1.06 to 1.18) | 0.02 | 79 | 15/7.4 | <0.01 |
| Obstetric, maternal | ||||||||||||
| BMI >30 v <25 | GDM | 30 | 7941/361 340 | 4.80 (4.43 to 5.21) | 3.78 (3.31 to 4.32) | <1−100 | 2.22 to 6.43 | 3.29 (2.31 to 4.70) | 0.70 | 74 | 25/28.0 | NA |
| BMI 25-30 v <25 | GDM | 17 | 6746/394 338 | 2.29 (2.12 to 2.47) | 1.97 (1.76 to 2.19) | 7.9−35 | 1.44 to 2.67 | 1.66 (1.29 to 2.13) | 0.52 | 56 | 11/13.7 | NA |
| BMI >30 v <25 | Instrumental delivery | 4 | 114 847/1 671 077 | 1.17 (1.13 to 1.21) | 1.17 (1.12 to 1.23) | 5.9−11 | 0.99 to 1.39 | 1.12 (0.98 to 1.29) | 0.96 | 51 | 3/3.7 | NA |
| BMI >30 v <25 | PPH | 7 | 95 586/1 692 216 | 1.19 (1.15 to 1.23) | 1.48 (1.27 to 1.73) | 6.0−7 | 0.94 to 2.34 | 1.31 (1.08 to 1.59) | 0.06 | 85 | 5/4.5 | 1.00 |
| GWG high v normal | PPWR (kg) at 0-1 years | 8 | 9229/17 657¶ | 2.50 (2.35 to 2.65) | 3.02 (2.31 to 3.73) | <1−100 | 0.66 to 5.38 | 2.31 (0.90 to 3.71) | 0.88 | 95 | 7/7.2 | NA |
| BMI >30 v <25 | Pre-eclampsia, unadj | 40 | 137 567/4 430 230 | 2.64 (2.59 to 2.70) | 2.82 (2.57 to 3.10) | <1−100 | 1.65 to 4.82 | 2.49 (1.98 to 3.13) | 0.78 | 98 | 38/38.6 | NA |
| BMI 25-30 v <25 | Pre-eclampsia, unadj | 38 | 106 770/3 271 222 | 1.96 (1.91 to 2.01) | 2.08 (1.98 to 2.19) | <1−100 | 1.65 to 2.63 | 1.87 (0.58 to 2.21) | 0.56 | 89 | 35/34.7 | 1.00 |
| BMI >30 v <25 | Pre-eclampsia, adj | 10 | 36 457/1 791 255 | 3.37 (3.25 to 3.49) | 2.93 (2.58 to 3.33) | <1−100 | 2.07 to 4.15 | 2.81 (1.70 to 4.66) | 0.11 | 67 | 10/10.0 | 1.00 |
| BMI >25 v <25 | PTB (induced) at <37 weeks’ gestation | 5 | 5664/133 307 | 1.28 (1.20 to 1.36) | 1.30 (1.23 to 1.37) | 2.7−22 | 1.19 to 1.41 | 1.35 (1.09 to 1.68) | 0.03 | 0 | 3/3.2 | NA |
| BMI >40 v 30-40 | PTB <37 weeks’ gestation | 19 | 43 266/516 546 | 1.17 (1.12 to 1.21) | 1.20 (1.13 to 1.27) | 9.4−10 | 1.01 to 1.42 | 1.14 (1.06 to 1.21) | 0.51 | 60 | 10/9.3 | 0.82 |
| BMI >40 v 30-35 | PTB <37 weeks’ gestation | 10 | 22 964/295 103 | 1.19 (1.14 to 1.24) | 1.31 (1.19 to 1.43) | 1.8−8 | 1.01 to 1.68 | 1.24 (1.09 to 1.41) | 0.44 | 70 | 7/5.0 | 0.34 |
BMI=body mass index; WG=weight gain; iya=in young adulthood; WC=waist circumference; LGA=large for gestational age; NA=not applicable, because estimated number is larger than observed, and there is no evidence of excess significance based on assumption made for plausible effect size; SGA=small for gestational age; GDM=gestational diabetes mellitus; PPH=postpartum haemorrhage; PPWR=postpartum weight retention; PTB=preterm birth; adj=effect estimate based on studies with adjusted risk estimates; unadj=effect estimate based on unadjusted raw numbers of included studies.
*From random effects model. RR for categorical outcome measure.
†P value of summary random effects estimate.
‡From Egger’s regression asymmetry test.
§Expected number of significant studies with point estimate of largest study (smallest SE) as plausible effect size. O/E=observed/expected number of studies with significant results. P value for excess significance test.
¶Mean difference.