Table 1.
Characteristics of pregnant women in the study cohort (n=2630)
| Characteristic | Total | Total GWG | |||
| Below (n=392) |
Average (n=1842) |
Above (n=396) |
P value | ||
| Maternal age (year), mean±SD | 29.4±3.6 | 29.9±3.8 | 29.4±3.5 | 28.5±3.6 | <0.0001 |
| Maternal age ≥35 years, n (%) | 241 (9.2) | 51 (13) | 169 (9.2) | 21 (5.3) | 0.0002 |
| Nulliparous, n (%) | 2216 (84.3) | 325 (82.9) | 1532 (83.2) | 359 (90.7) | 0.0027 |
| Education, university degree and above, n (%) | 2404 (91.5) | 362 (92.6) | 1702 (92.5) | 340 (85.7) | 0.0007 |
| ART, n (%) | 55 (2.1) | 9 (2.3) | 37 (2) | 9 (2.3) | 0.9834 |
| Tobacco smoking, n (%) | 72 (2.7) | 7 (1.8) | 41 (2.2) | 24 (6.1) | <0.0001 |
| Alcohol use, n (%) | 338 (12.9) | 52 (13.3) | 240 (13) | 46 (11.6) | 0.7221 |
| Prepregnancy BMI (kg/m2), mean±SD | 21.3±3.0 | 21.7±3.1 | 21.2±3.0 | 21.5±2.9 | 0.0139 |
| Prepregnancy BMI categories, n (%) | |||||
| Underweight (<18.5 kg/m2) | 396 (15.1) | 54 (13.8) | 292 (15.9) | 50 (12.6) | 0.7530 |
| Normal weight (18.5–24.9 kg/m2) | 1980 (75.3) | 298 (76) | 1372 (74.5) | 310 (78.3) | |
| Overweight and obese (≥25 kg/m2) | 254 (9.7) | 40 (10.2) | 178 (9.7) | 36 (9.1) | |
| Gestational age at the first prenatal visit (week), median (IQR) | 15 (3) | 14 (3) | 15 (3) | 15 (3) | 0.1986 |
| GWG in early pregnancy by BMI categories (kg), mean±SD | |||||
| All women | 2.2±2.9 | −0.2±2.8 | 2.1±2.2 | 4.9±3.2 | <0.0001 |
| Underweight (<18.5 kg/m2) | 2.5±2.4 | 0.9±1.9 | 2.4±2.0 | 4.8±3.0 | <0.0001 |
| Normal weight (18.5–24.9 kg/m2) | 2.3±2.8 | 0.0±2.8 | 2.2±2.2 | 4.9±3.1 | <0.0001 |
| Overweight and obese (≥25 kg/m2) | 1.4±3.6 | −2.2±3.3 | 1.5±2.6 | 4.7±4.4 | <0.0001 |
| GWG in late pregnancy by BMI categories (kg), mean±SD | |||||
| All women | 13.0±3.5 | 8.2±3.0 | 12.6±2.9 | 17.8±3.6 | <0.0001 |
| Underweight (<18.5 kg/m2) | 13.0±3.5 | 8.9±1.9 | 12.8±2.5 | 18.2±3.8 | <0.0001 |
| Normal weight (18.5–24.9 kg/m2) | 12.9±4.0 | 8.4±3.0 | 12.8±2.8 | 17.8±3.6 | <0.0001 |
| Overweight and obese (≥25 kg/m2) | 11.0±4.9 | 5.8±3.3 | 10.8±3.8 | 17.4±3.8 | <0.0001 |
| GWG in whole pregnancy by BMI categories (kg), mean±SD | |||||
| All women | 15.0±4.9 | 8.1±2.6 | 14.8±2.7 | 22.7±2.9 | <0.0001 |
| Underweight (<18.5 kg/m2) | 15.4±4.2 | 9.7±1.6 | 15.2±2.3 | 23.1±3.0 | <0.0001 |
| Normal weight (18.5–24.9 kg/m2) | 15.2±4.7 | 8.4±2.1 | 15.0±2.5 | 22.7±2.8 | <0.0001 |
| Overweight and obese (≥25 kg/m2) | 12.3±6.1 | 3.7±2.4 | 12.3±3.7 | 22.0±3.6 | <0.0001 |
| Gestational age at delivery (week), median (IQR) | 39 (2) | 39 (2) | 39 (2) | 39 (2) | 0.0793 |
| Birth weight (g), mean±SD | 3376±450 | 3238±422 | 3370±438 | 3540±480 | <0.0001 |
| Male infant, n (%) | 1334 (51.4) | 194 (50.4) | 945 (52) | 195 (49.5) | 0.7951 |
ART, assisted reproductive technology; BMI, body mass index; GWG, gestational weight gain.