Table 1.
Demographic and clinical characteristics of mothers according to employment status (n = 1,316,310)
| Variables | Employed |
Nonemployed |
P for difference |
|---|---|---|---|
| n = 852,045 | n = 464,265 | ||
| Maternal age (years) | |||
| 20–24 | 15,939 (1.9) | 10,335 (2.2) | <.001 |
| 25–29 | 227,344 (26.7) | 106,521 (22.9) | |
| 30–34 | 460,563 (54.1) | 223,190 (48.1) | |
| 35–39 | 131,218 (15.4) | 98,095 (21.1) | |
| 40–44 | 16,339 (1.9) | 24,883 (5.4) | |
| ≥45 | 549 (0.1) | 1142 (0.2) | |
| Residence | |||
| Outside of the Seoul Metropolitan Area∗ | 615,127 (72.2) | 359,937 (77.5) | <.001 |
| Income Level | |||
| 1Q (lowest) | 154,486 (18.1) | 76,243 (16.4) | <.001 |
| 2Q | 258,189 (30.3) | 101,051 (21.8) | |
| 3Q | 325,854 (38.2) | 174,583 (37.6) | |
| 4Q (richest) | 113,516 (13.3) | 112,388 (24.2) | |
| Disability Status | |||
| Disability | 3164 (0.4) | 2412 (0.5) | <.001 |
| Plurality | |||
| Multiple gestation | 19,578 (2.3) | 14,557 (3.1) | <.001 |
| Pre-conceptional BMI (kg/m2) | |||
| <18.5 | 363,512 (42.7) | 171,338 (36.9) | <.001 |
| 18.5–25 | 416,556 (48.9) | 258,183 (55.6) | |
| 25–30 | 60,871 (7.1) | 28,308 (6.1) | |
| >30 | 11,106 (1.3) | 6436 (1.4) | |
| Pre-conceptional fasting blood glucose | |||
| Normal (<100 mg/dl) | 805,147 (94.5) | 428,805 (92.4) | <.001 |
| Impaired glucose tolerance (100–125 mg/dl) | 43,878 (5.2) | 33,145 (7.1) | |
| Diabetes (≥126 mg/dl) | 3020 (0.4) | 2315 (0.5) | <.001 |
| Pre-conceptional smoking | 33,348 (3.9) | 43,522 (9.4) | <.001 |
1Q, lowest quartile; 2Q, 2nd lowest quartile; 3Q, third quartile; 4Q, fourth (highest quartile). BMI, body mass index. All compositions were significantly different between the two groups due to differences in size and the large sample size.
∗
Seoul capital area includes Seoul, Incheon, and Gyeonggi Province, located in northwestern Republic of Korea.