Table 2.
Associations between maternal Hb concentrations up to 14 weeks of gestation and other maternal characteristics and risk of miscarriage.
| Miscarriage | Unadjusted Model | Adjusted Model * | ||||||
|---|---|---|---|---|---|---|---|---|
| Maternal Characteristics | No. of Participants | n | % | OR (95% CI) | p-Value | OR (95% CI) | p-Value | |
| Hb concentration up to 14 weeks of gestation (g/L) | ||||||||
| <110 | 358 | 30 | 8.4 | 1.72 (1.17 to 2.52) | 0.006 | 2.08 (1.35 to 3.20) | <0.001 | |
| 110–139 | 8505 | 430 | 5.1 | 1.00 (ref.) | 1.00 (ref.) | |||
| ≥140 | 590 | 60 | 10.2 | 2.13 (1.60 to 2.82) | <0.001 | 1.78 (1.25 to 2.54) | 0.001 | |
| Maternal age at conception (years) | ||||||||
| <20 | 331 | 17 | 5.1 | 1.28 (0.76 to 2.18) | 0.35 | 1.10 (0.59 to 2.07) | 0.75 | |
| 20–24 | 1357 | 56 | 4.1 | 1.02 (0.73 to 1.43) | 0.90 | 0.80 (0.53 to 1.20) | 0.29 | |
| 25–29 | 2498 | 101 | 4.0 | 1.00 (ref) | 1.00 (ref) | |||
| 30–34 | 2716 | 148 | 5.5 | 1.37 (1.06 to 1.77) | 0.017 | 1.36 (1.01 to 1.84) | 0.041 | |
| 34–39 | 1685 | 122 | 7.2 | 1.85 (1.41 to 1.77) | <0.001 | 2.01 (1.47 to 2.75) | <0.001 | |
| ≥40 | 337 | 52 | 15.4 | 4.33 (3.03 to 6.18) | <0.001 | 4.83 (3.22 to 7.25) | <0.001 | |
| BMI in the first trimester (Kg/m2) | ||||||||
| <18.5 | 249 | 6 | 2.4 | 0.49 (0.22 to 1.11) | 0.09 | 0.67 (0.29 to 1.54) | 0.35 | |
| 18.5–24.9 | 5127 | 246 | 4.8 | 1.00 (ref) | 1.00 (ref) | |||
| ≥25 | 3559 | 217 | 6.1 | 1.29 (1.07 to 1.55) | 0.008 | 1.17 (0.94 to 1.45) | 0.154 | |
| Smoking habit | ||||||||
| No | 6926 | 340 | 4.9 | 1.00 (ref) | 1.00 (ref) | |||
| Yes | 1781 | 74 | 4.2 | 0.84 (0.65 to 1.09) | 0.18 | 0.84 (0.63 to 1.10) | 0.20 | |
| Parity | ||||||||
| Nulliparous | 4064 | 247 | 6.1 | 1.00 (ref) | 1.00 (ref) | |||
| Parous | 5259 | 261 | 4.9 | 0.81 (0.67 to 0.96) | 0.021 | 0.69 (0.55 to 0.86) | 0.001 | |
| Previous miscarriage | ||||||||
| 0 | 6609 | 354 | 5.4 | 1.00 (ref) | 1.00 (ref) | |||
| 1 | 2067 | 111 | 5.4 | 1.00 (0.81 to 1.24) | 0.98 | 0.87 (0.65 to 1.64) | 0.25 | |
| ≥2 | 647 | 43 | 6.7 | 1.26 (0.91 to 1.74) | 0.16 | 1.11 (0.75 to 1.64) | 0.61 | |
BMI, body mass index; OR, odds ratio; CI, confidence interval. * Logistic regression model was mutually adjusted for all characteristics displayed in this table.