Table 1. Comparison of perinatal, socioeconomic and cognitive development characteristics of preterm and full-term infants.
| Measures | Full term group | Preterm group | Comparisons | |||
|---|---|---|---|---|---|---|
| Test | p-value | |||||
| Perinatal characteristics* | ||||||
| Birth weight (g) | 3213.0±290.6 | 1603.6±517.9 | -11.53† | <0.001 | ||
| Gestational age (weeks) | 39.4±3.5 | 31.2±1.9 | -9.03† | <0.001 | ||
| Head circumference at birth (cm) | 33.7±1.1 | 28.8±2.4 | -8.23‡ | <0.001 | ||
| Male gender | 14 (70) | 9 (45.0) | -1.60§ | 0.110 | ||
| Cesarean delivery | 7 (35) | 14 (70) | 2.76§ | 0.005 | ||
| Apgar (5 minutes) | 7 | 0 (0) | 1 (5) | 1.38 | 0.711 | |
| 8 | 1 (5) | 1 (5) | ||||
| 9 | 12 (60) | 13 (65) | ||||
| 10 | 7 (35) | 5 (25) | ||||
| Small for gestational age | 0 (0) | 1 (5) | - | - | ||
| Antenatal corticosteroids// | None | 20 (100) | 4 (20) | - | - | |
| Complete | 0 (0) | 11 (55) | - | - | ||
| Incomplete | 0 (0) | 5 (25) | - | - | ||
| Sepsis | 0 (0) | 3 (15) | - | - | ||
| Intraventricular hemorrhage grade I or II | 0 (0) | 5 (25) | - | - | ||
| Membrane hialyne disease | 0 (0) | 6 (30) | - | - | ||
| Bronchopulmonary dysplasia | 0 (0) | 4 (20) | - | - | ||
| Necrotizing enterocolitis | 0 (0) | 4 (20) | - | - | ||
| Socioeconomic characteristics | ||||||
| Socioeconomic level (CCEB)¶ | B1 | 1 (5) | 2(10) | 2.74§ | 0.098 | |
| B2 | 9 (45) | 4 (20) | ||||
| C1 | 5 (25) | 5 (25) | ||||
| C2 | 4 (20) | 7 (35) | ||||
| D | 1 (5) | 2 (10) | -0.50‡ | |||
| Maternal age | 28.2±5.4 | 27.2±7.1 | 0.620 | |||
| Maternal education (years) | < 4 | 0(0) | 2(10) | 2.86§ | 0.582 | |
| 4–7 | 3(15) | 2(10) | ||||
| 8–11 | 4(20) | 6(30) | ||||
| 12–14 | 10(50) | 6(30) | ||||
| ≥15 | 3(15) | 4(20) | ||||
| Paid maternal employment | 13(65) | 9(45) | 2.37§ | 0.124 | ||
| Cognitive development Comparisons (Bayley-III) | ||||||
| Cognitive score at 6 mo | 115.7±14.2 | 103.0±10.8 | -3.20‡ | 0.002 | ||
| Age(days) of 6 mo assessment | 204.2±10.1 | 193.2±13.2 | -2.96‡ | 0.005 | ||
| Cognitive score at 12 mo | 120.0±12.0 | 110.85±12.5 | -2.56‡ | 0.024 | ||
| Age(days) of 12 mo assessment | 372.6±10.7 | 376.8±14.7 | 1.04‡ | 0.300 | ||
*
Data are presented in Mean±standard deviation or number (%);
†
Mann-Whitney test;
‡
T-test for independent samples;
§
Chi-square test for independent samples;
//
A complete cycle of antenatal corticosteroids was considered as two doses of 12 mg intramuscular (IM) betamethasone 24 hours apart or four doses of 6 mg IM dexamethasone 12 hours apart in pregnancies at risk of preterm delivery between 24 and 34 weeks of gestational age, according to national and international protocols;
¶
The CCEB (Criterion of Economic Classification Brazil) stratify the population according to average monthly income into groups: A ($3,523 or higher), B1 ($1,917), B2 ($995), C1 ($595), C2 ($407) and D/E (until $285).