Table 1. Baseline characteristics of the study population according to maternal age.
| Baseline characteristics | Entire cohort N = 565 | Age grouped | ||
|---|---|---|---|---|
| Control group (N = 361) | Advanced maternal age group (N = 204) | P-value | ||
| Maternal age (yeas) | 31 (27–35) | 28 (26–30) | 36 (35–38) | < 0.001c* |
| Education (years) | 15.02 ± 2.40 | 15.11 ± 2.16 | 14.86 ± 2.77 | 0.227d |
| ≤ 12a | 107 (18.90) | 57 (15.80) | 50 (24.50) | |
| 12–16b | 414 (73.30) | 281 (77.80) | 133 (65.20) | |
| > 16 | 44 (7.80) | 23 (6.40) | 21 (10.30) | |
| Maternal height (cm) | 161.94 ± 4.62 | 162.07 ± 4.58 | 161.72 ± 4.70 | 0.559d |
| Pre–gestational weight (kg) | 56.00 (51.50–62.00) | 55.00 (50.50–62.00) | 58.00 (53.00–63.00) | 0.005c* |
| Pre–gestational BMI (kg/m2) | 21.48 (19.66–23.62) | 20.94 (19.29–23.44) | 22.05 (20.43–23.89) | < 0.001c* |
| –18.5 | 65 (11.50) | 54 (15.00) | 11 (5.40) | |
| 18.5–23 | 328 (58.10) | 205 (56.80) | 123 (60.30) | |
| 23–27.5 | 135 (23.90) | 80 (22.20) | 55 (27.00) | |
| 27.5– | 37 (6.50) | 22 (6.00) | 15 (7.30) | |
| Age at menarche (years) | 13.73 ± 1.28 | 13.71 ± 1.25 | 13.77 ± 1.34 | 0.878d |
| Parity (numbers) | 2.12 ± 1.18 | 1.83 ± 1.08 | 2.63 ± 1.19 | < 0.001d* |
| ≥ 2 (n (%)) | 287 (50.80) | 112 (31.02) | 175 (85.78) | |
| Abortion | 0.82 ± 1.05 | 0.63 ± 0.95 | 1.15 ± 1.14 | < 0.001d* |
| Family history of hypertension (n (%)) | 55 (9.73) | 38 (10.53) | 17 (8.33) | 0.399e |
| Family history of diabetes (n (%)) | 32 (5.66) | 23 (6.37) | 9 (4.41) | 0.334e |
Data are presented as n (%), mean ± SD, or median (interquartile range) as appropriate.
* Statically significant P-value < 0.05.
a: Accepted education for 12 years means already obtained the degree of high school.
b: Accepted education for 16 years means already obtained the degree of bachelor.
c: Mann-Whitney U test for comparison of skew distribution quantitative variables between the control group and the advanced maternal age group.
d: Student's t test for comparison of normally distributed quantitative variables between the control group and the advanced maternal age group.
e: χ2 test and Fisher's Exact Test for comparison of qualitative variables between the control group and the advanced maternal age group.
Abbreviation: BMI: body mass index.