Table 3.
Association between adverse birth outcomes and BMI in the overall cohort
| N (%) N = 2921 |
Unadjusted Models | Adjusted Models | |||
|---|---|---|---|---|---|
| OR (95% CI) | p-value | aOR (95% CI) | p-value | ||
| Delivery GA (weeks) | |||||
| Spontaneous PTD (<37 weeks GA) | 293 (10.0) | ||||
| Normal | 102 (12.4) | 1.00 | 1.00 | ||
| Underweight | 16 (19.0) | 1.71 (0.95, 3.09) | 0.076 | 1.69 (0.70, 4.11) | 0.244 |
| Overweight | 75 (10.5) | 0.87 (0.63, 1.19) | 0.381 | 0.96 (0.62, 1.49) | 0.870 |
| Obese | 100 (7.7) | 0.63 (0.47, 0.85) | 0.002 | 0.65 (0.43, 0.99) | 0.043 |
| Provider-Initiated PTD (<37 weeks GA) | 188 (6.4) | ||||
| Normal | 40 (4.9) | 1.00 | 1.00 | ||
| Underweight | 4 (4.8) | 1.09 (0.38, 3.15) | 0.874 | 1.54 (0.34, 6.95) | 0.572 |
| Overweight | 47 (6.6) | 1.39 (0.89, 2.14) | 0.144 | 1.37 (0.68, 2.76) | 0.377 |
| Obese | 97 (7.5) | 1.56 (1.07, 2.29) | 0.022 | 1.74 (0.94, 3.21) | 0.077 |
| Birth weight (g) | |||||
| Low (<2500) | 385 (13.2) | ||||
| Normal | 129 (15.7) | 1.00 | 1.00 | ||
| Underweight | 16 (19.1) | 1.29 (0.72, 2.30) | 0.394 | 1.16 (0.57, 2.37) | 0.688 |
| Overweight | 93 (13.0) | 0.84 (0.63, 1.12) | 0.232 | 0.79 (0.56, 1.12) | 0.187 |
| Obese | 147 (11.3) | 0.71 (0.55, 0.92) | 0.009 | 0.60 (0.44, 0.82) | 0.001 |
| High (>4000) | 125 (4.3) | ||||
| Normal | 20 (2.4) | 1.00 | 1.00 | ||
| Underweight | 2 (2.4) | 1.04 (0.24, 4.54) | 0.961 | 0.69 (0.09, 5.42) | 0.722 |
| Overweight | 33 (4.6) | 1.92 (0.09, 3.38) | 0.024 | 2.14 (1.09, 4.18) | 0.027 |
| Obese | 70 (5.4) | 2.19 (1.32, 3.63) | 0.002 | 2.54 (1.39, 4.66) | 0.002 |
| Size for GA (centile) | |||||
| Small (<10th) | 362 (12.3) | ||||
| Normal | 124 (15.1) | 1.00 | 1.00 | ||
| Underweight | 17 (20.2) | 1.64 (0.91, 2.94) | 0.100 | 1.63 (0.81, 3.30) | 0.173 |
| Overweight | 103 (14.4) | 1.02 (0.77, 1.36) | 0.886 | 0.98 (0.70, 1.37) | 0.903 |
| Obese | 118 (9.1) | 0.63 (0.48, 0.83) | 0.001 | 0.57 (0.41, 0.79) | 0.001 |
| Large (>90th) | 378 (12.9) | ||||
| Normal | 81 (9.9) | 1.00 | 1.00 | ||
| Underweight | 8 (9.5) | 1.18 (0.54, 2.58) | 0.681 | 1.15 (0.46, 2.87) | 0.760 |
| Overweight | 79 (11.0) | 1.20 (0.86, 1.67) | 0.285 | 1.27 (0.87, 1.87) | 0.221 |
| Obese | 210 (16.2) | 1.72 (1.31, 2.27) | <0.001 | 1.66 (1.20, 2.31) | 0.002 |
| Pregnancy outcome | |||||
| Stillbirth/Miscarriage | 91 (3.1) | ||||
| Normal | 22 (2.7) | 1.00 | 1.00 | ||
| Underweight | 2 (2.4) | 0.88 (0.20, 3.82) | 0.866 | 0.56 (0.07, 4.23) | 0.575 |
| Overweight | 31 (4.3) | 1.64 (0.94, 2.86) | 0.082 | 0.63 (0.30, 1.31) | 0.219 |
| Obese | 36 (2.8) | 1.04 (0.61, 1.78) | 0.891 | 0.67 (0.37, 1.23) | 0.192 |
OR - odds ratio, GA - gestational age, PTD - preterm delivery
Preterm model: adjusted for maternal age, HIV status, haemoglobin, parity, previous PTD
Birth weight, size for GA and birth outcome models: adjusted for maternal age, HIV status, haemoglobin and parity. Missing data, n (%): GA at delivery n=232 (7.9), Birthweight n=49 (1.7), Size for GA n=232 (7.9), Pregnancy outcome n=16 (0.6). Where data are missing on outcomes, cases were excluded on the regression. Interpretation of OR’s: Compared to normal BMI, underweight/overweight/obese BMI increases (OR>1) or decreases (OR<1) the likelihood of having spontaneous PTD/PI-PTD/LBW/HBW/SGA/LGA/Stillbirth/Miscarriage