Table 1.
Maternal and neonatal baseline characteristics of the study and control groups
| Characteristic | Term infants exposed to ACS n=5423 |
Term infants NOT exposed to ACS n=523 782 |
P value |
| Maternal age (years) | 29.50±5.87 | 29.97±5.48 | <0.001 |
| >35 years | 847 (15.6%) | 82 860 (15.8%) | 0.69 |
| Parity | 0.002 | ||
| 0 (nulliparity) | 2298 (42.4%) | 226 739 (43.3%) | |
| 1 | 1927 (35.5%) | 190 250 (36.3%) | |
| 2 | 777 (14.3%) | 72 454 (13.8%) | |
| ≥3 | 421 (7.8%) | 34 339 (6.6%) | |
| Income quintile* | 0.02 | ||
| Q1 (lowest) | 1308 (24.1%) | 117 423 (22.4%) | |
| Q2 | 1059 (19.5%) | 105 093 (20.1%) | |
| Q3 | 1110 (20.5%) | 107 509 (20.5%) | |
| Q4 | 1104 (20.4%) | 109 147 (20.8%) | |
| Q5 (highest) | 842 (15.5%) | 84 610 (16.2%) | |
| Chronic hypertension | 60 (1.1%) | 3317 (0.6%) | <0.001 |
| Pregestational diabetes | 126 (2.3%) | 7467 (1.4%) | <0.001 |
| Hypertensive complications† | 298 (5.5%) | 22 552 (4.3%) | <0.001 |
| Gestational diabetes | 345 (6.4%) | 23 961 (4.6%) | <0.001 |
| Gestational age at birth | <0.001 | ||
| 370/7 to 386/7 weeks | 2598 (47.9%) | 148 843 (28.4%) | |
| 390/7 to 406/7 weeks | 2396 (44.2%) | 301 183 (57.5%) | |
| ≥410/7 weeks | 429 (7.9%) | 73 756 (14.1%) | |
| Induction of labour | 1596 (29.4%) | 126 925 (24.2%) | <0.001 |
| Caesarean delivery | 1501 (27.7%) | 139 062 (26.5%) | 0.06 |
| Forceps/vacuum delivery | 621 (11.5%) | 64 800 (12.4%) | 0.04 |
| Neonatal characteristics | |||
| Birth weight (g) | 3315±496 | 3447±468 | <0.001 |
| Birth weight <10th percentile‡ | 656 (12.1%) | 45 989 (8.8%) | <0.001 |
| Male sex | 2738 (50.5%) | 265 003 (50.6%) | 0.88 |
| 5 min Apgar<7 | 42 (0.8%) | 3714 (0.7%) | 0.57 |
| Resuscitation at birth | 856 (15.8%) | 75 305 (14.4%) | 0.003 |
| NICU admission | 179 (3.3%) | 10 121 (1.9%) | <0.001 |
Data are presented as mean±SD or n (%).
*Measured ecologically as the neighbourhood household income, divided into quintiles.
†Refers to gestational hypertension or pre-eclampsia.
‡Based on the national reference charts by Kramer et al.57
ACS, antenatal corticosteroids; NICU, neonatal intensive care unit