Table 3.
The associations between maternal mortality and income levels, stratified by maternal age, residential areas, mode of delivery, and maternal comorbidities after adjusting for all covariates.
| Household Income | |||||||||
|---|---|---|---|---|---|---|---|---|---|
| 1Q (Lowest) | 2Q | 3Q | 4Q (Highest) (Reference) |
p for Interaction | |||||
| RR | (95% CI) | RR | (95% CI) | RR | (95% CI) | RR | (95% CI) | ||
| Maternal mortality within 6 weeks after childbirth | |||||||||
| Age * | 0.0395 | ||||||||
| 15–19 | - | - | - | 1.00 | |||||
| 20–24 | - | - | - | 1.00 | |||||
| 25–29 | 2.79 | (1.34, 5.80) | 1.66 | (0.79, 3.51) | 1.07 | (0.49, 2.34) | 1.00 | ||
| 30–34 | 1.29 | (0.71, 2.35) | 1.29 | (0.74, 2.23) | 1.35 | (0.81, 2.24) | 1.00 | ||
| 35–39 | 3.40 | (1.59, 7.29) | 2.81 | (1.33, 5.93) | 1.58 | (0.74, 3.37) | 1.00 | ||
| 40+ | - | - | - | 1.00 | |||||
| Residential areas ** | 0.9392 | ||||||||
| Seoul metropolitan | 2.48 | (1.19, 5.17) | 1.41 | (0.67, 2.98) | 1.78 | (0.91, 3.49) | 1.00 | ||
| Other metropolitans | 2.35 | (1.03, 5.37) | 1.76 | (0.78, 4.00) | 1.42 | (0.63, 3.21) | 1.00 | ||
| Small cities | 2.48 | (1.42, 4.33) | 2.10 | (2.10, 3.62) | 1.54 | (0.90, 2.65) | 1.00 | ||
| Rural areas | 2.24 | (0.47, 10.78) | 2.56 | (2.56, 11.95) | 1.46 | (0.29, 7.35) | 1.00 | ||
| Mode of delivery † | 0.1939 | ||||||||
| Spontaneous vaginal delivery | 1.92 | (0.70, 5.25) | 1.45 | (0.54, 3.94) | 1.79 | (0.71, 4.53) | 1.00 | ||
| Instrumental delivery | 1.13 | (0.52, 2.47) | 0.78 | (0.35, 1.71) | 0.65 | (0.30, 1.40) | 1.00 | ||
| Cesarean section | 3.23 | (1.97, 5.27) | 2.60 | (1.61, 4.22) | 2.01 | (1.24, 3.24) | 1.00 | ||
| Maternal comorbidities ‡ | 0.1789 | ||||||||
| No | 1.60 | (0.81, 3.14) | 1.10 | (0.56, 2.16) | 0.99 | (0.51, 1.92) | 1.00 | ||
| Yes | 2.87 | (1.81, 4.55) | 2.32 | (1.48, 3.65) | 1.88 | (1.21, 2.93) | 1.00 | ||
| Maternal mortality within 1 year after childbirth | |||||||||
| Age * | 0.1173 | ||||||||
| 15–19 | - | - | - | 1.00 | |||||
| 20–24 | 1.86 | (0.74, 4.70) | 1.64 | (0.66, 4.09) | 1.31 | (0.50, 3.43) | 1.00 | ||
| 25–29 | 2.07 | (1.36, 3.14) | 1.42 | (0.93, 2.16) | 1.07 | (0.70, 1.65) | 1.00 | ||
| 30–34 | 1.46 | (1.05, 2.04) | 1.09 | (0.79, 1.50) | 1.10 | (0.82, 1.49) | 1.00 | ||
| 35–39 | 2.15 | (1.27, 3.63) | 2.23 | (1.35, 3.67) | 1.13 | (0.68, 1.89) | 1.00 | ||
| 40+ | 2.56 | (0.84, 7.77) | 2.33 | (0.78, 6.97) | 1.75 | (0.58, 5.23) | 1.00 | ||
| Residential areas ** | 0.0177 | ||||||||
| Seoul metropolitan | 1.78 | (1.14, 2.77) | 1.07 | (0.68, 1.66) | 1.27 | (0.85, 1.90) | 1.00 | ||
| Other metropolitans | 2.90 | (1.73, 4.88) | 1.90 | (1.12, 3.20) | 1.26 | (0.74, 2.14) | 1.00 | ||
| Small cities | 1.60 | (1.18, 2.19) | 1.29 | (0.95, 1.75) | 1.10 | (0.82, 1.48) | 1.00 | ||
| Rural areas | 1.24 | (0.53, 2.89) | 2.03 | (0.92, 4.48) | 1.03 | (0.44, 2.41) | 1.00 | ||
| Mode of delivery † | 0.3537 | ||||||||
| Spontaneous vaginal delivery | 1.85 | (1.10, 3.12) | 1.50 | (0.90, 2.51) | 1.48 | (0.90, 2.43) | 1.00 | ||
| Instrumental delivery | 1.34 | (0.87, 2.06) | 1.24 | (0.82, 1.88) | 0.80 | (0.53, 1.22) | 1.00 | ||
| Cesarean section | 2.08 | (1.56, 2.78) | 1.47 | (1.10, 1.96) | 1.26 | (0.95, 1.67) | 1.00 | ||
| Maternal comorbidities ‡ | 0.0267 | ||||||||
| No | 1.49 | (1.10, 2.05) | 0.98 | (0.72, 1.35) | 0.88 | (0.65, 1.21) | 1.00 | ||
| Yes | 2.13 | (1.58, 2.88) | 1.86 | (1.39, 2.49) | 1.43 | (1.08, 1.91) | 1.00 | ||
RR: risk ratio. * Adjusted for type of insurance, residential area, working status, mode of delivery, preterm birth, prenatal care, multiple birth, maternal comorbidities, type of hospital, and year of delivery. ** Adjusted for maternal age, type of insurance, working status, mode of delivery, preterm birth, prenatal care, multiple birth, maternal comorbidities, type of hospital, and year of delivery. † Adjusted for maternal age, type of insurance, residential area, working status, preterm birth, prenatal care, multiple birth, maternal comorbidities, type of hospital, and year of delivery. ‡ Adjusted for maternal age, type of insurance, residential area, working status, mode of delivery, preterm birth, prenatal care, multiple birth, type of hospital, and year of delivery.