Associations between demographic, obstetric and neonatal factors and cognitive impairment at 2 years corrected age in LMPT infants
| Variable | Cognitive impairment (n=40) | Univariable analyses | p Value | Multivariable analyses | p Value | |
|---|---|---|---|---|---|---|
| Obstetric/neonatal risk factor present, n (%)‡ | Obstetric/neonatal risk factor absent, n (%)‡ | RR (95% CI) | RR (95% CI) | |||
| Obstetric risk factors | ||||||
| Mother’s age | ||||||
| <20 years | 1 (5.0) | 39 (6.3) | 1.31 (0.16 to 10.17) | 0.793 | – | – |
| 20–24 years | 8 (9.0) | 32 (5.8) | 2.36 (0.88 to 6.32) | 0.086 | – | – |
| 25–29 years | 7 (3.8) | 33 (7.3) | Baseline | – | – | – |
| 30–34 years | 11 (5.1) | 29 (6.9) | 1.33 (0.52 to 3.37) | 0.544 | – | – |
| 35+ years | 13 (10.4) | 27 (5.3) | 2.73 (1.12 to 6.67) | 0.027 | – | – |
| Non-white ethnic group | 13 (10.1) | 27 (5.4) | 1.88 (1.00 to 3.55) | 0.050 | 2.06 (1.10 to 3.83) | 0.023 |
| Non-English speaking at home | 6 (7.5) | 33 (6.1) | 1.23 (0.53 to 2.84) | 0.632 | – | – |
| SES-Index | ||||||
| Low risk | 8 (2.8) | 32 (9.1) | Baseline | – | – | – |
| Medium risk | 18 (9.2) | 22 (4.8) | 3.26 (1.44 to 7.35) | 0.004 | 2.86 (1.24 to 6.57) | 0.013 |
| High risk | 14 (9.0) | 26 (5.3) | 3.19 (1.36 to 7.43) | 0.007 | 2.36 (1.02 to 5.48) | 0.046 |
| Conceived via infertility treatment | 0 | 40 (6.9) | – | – | – | – |
| Pre-pregnancy diagnosed diabetes | 1 (4.6) | 39 (6.4) | 0.72 (0.10 to 4.99) | 0.735 | – | – |
| Pre-pregnancy diagnosed hypertension | 3 (20.0) | 37 (6.0) | 3.36 (1.16 to 9.69) | 0.025 | – | – |
| Smoked during pregnancy* | 11 (8.6) | 29 (5.7) | 1.50 (0.76 to 2.94) | 0.238 | – | – |
| Drank alcohol during pregnancy† | 18 (6.3) | 22 (6.3) | 1.00 (0.54 to 1.86) | 0.997 | – | – |
| Recreational drugs used during pregnancy‡ | 1 (8.3) | 39 (6.3) | 1.33 (0.22 to 7.86) | 0.750 | – | – |
| Preeclampsia | 12 (12.8) | 28 (5.2) | 2.47 (1.25 to 4.87) | 0.009 | 2.51 (1.33 to 4.70) | 0.004 |
| Infection (+culture) during pregnancy | 1 (11.1) | 39 (6.2) | 1.79 (0.27 to 11.66) | 0.544 | – | – |
| Gestational diabetes | 3 (12.5) | 36 (5.9) | 2.11 (0.71 to 6.26) | 0.176 | – | – |
| Pre-labour rupture of membranes >24 h | 7 (5.7) | 33 (6.5) | 0.88 (0.39 to 1.95) | 0.745 | – | – |
| Antenatal corticosteroids given | 8 (4.6) | 31 (6.8) | 0.68 (0.31 to 1.46) | 0.320 | – | – |
| Labour induced | 9 (6.6) | 30 (6.0) | 1.10 (0.53 to 2.28) | 0.800 | – | – |
| Raised CRP during labour (>5 mg/L) | 1 (4.2) | 38 (6.5) | 0.64 (0.09 to 4.19) | 0.645 | – | – |
| Normal vaginal delivery | 20 (6.2) | 20 (6.4) | 0.98 (0.53 to 1.82) | 0.952 | – | – |
| Absent or reversed end diastolic flow | 2 (7.7) | 38 (6.2) | 1.23 (0.30 to 4.96) | 0.766 | – | – |
| Neonatal risk factors | ||||||
| Male | 36 (10.5) | 4 (1.4) | 7.74 (2.77 to 21.55) | <0.001 | 7.04 (2.52 to 19.67) | <0.001 |
| Gestational age | ||||||
| 36 weeks | 22 (8.0) | 18 (5.0) | Baseline | – | – | – |
| 35 weeks | 6 (3.6) | 34 (7.2) | 0.45 (0.18 to 1.10) | 0.080 | – | – |
| 34 weeks | 8 (7.3) | 32 (6.1) | 0.91 (0.40 to 2.01) | 0.807 | – | – |
| 33 weeks | 3 (6.3) | 37 (6.3) | 0.78 (0.24 to 2.48) | 0.671 | – | – |
| 32 weeks | 1 (2.6) | 39 (6.5) | 0.33 (0.04 to 2.39) | 0.271 | – | – |
| Multiple birth | 4 (3.7) | 36 (6.8) | 0.55 (0.16 to 1.85) | 0.333 | – | – |
| Small for gestational age§ | – | – | – | – | – | – |
| >10th centile | 35 (6.2) | 5 (6.8) | Baseline | – | – | – |
| >3rd and ≤10th centile | 2 (5.0) | 38 (6.4) | 0.80 (0.19 to 3.24) | 0.759 | – | – |
| ≤3rd centile | 3 (9.1) | 37 (6.1) | 1.46 (0.47 to 4.55) | 0.511 | – | – |
| Resuscitated at birth | 8 (7.1) | 32 (6.1) | 1.16 (0.54 to 2.43) | 0.702 | – | – |
| Any respiratory support received¶ | 6 (7.1) | 34 (6.2) | 1.14 (0.49 to 2.67) | 0.755 | – | – |
| Intracranial abnormality** | 0 (0) | 40 (6.3) | – | – | – | – |
| Jaundice requiring phototherapy | 2 (4.1) | 36 (6.6) | 0.62 (0.15 to 2.52) | 0.502 | – | – |
| Hypoglycaemia (<2 mmol/L) | 4 (9.3) | 36 (6.1) | 1.53 (0.57 to 4.11) | 0.396 | – | – |
| Hypothermia (<36°C) | 7 (13.0) | 33 (5.7) | 2.29 (1.06 to 4.93) | 0.035 | – | – |
| Antibiotics given | 16 (7.3) | 24 (5.8) | 1.27 (0.68 to 2.34) | 0.445 | – | – |
| Any breast milk at discharge†† | 17 (4.3) | 23 (9.5) | 0.46 (0.24 to 0.84) | 0.011 | 0.52 (0.28 to 0.95) | 0.032 |
Data are shown for all independent variables entered in univariable analyses, and for factors that were significant independent predictors in multivariable analyses.
*Smoked during pregnancy is classified as mothers who smoked at least one cigarette per day at any time during pregnancy versus <1 cigarette per day; data were missing for two mothers.
†Drank alcohol during pregnancy is classified as mothers who drank any alcohol at any time during pregnancy versus no alcohol.
‡Recreational drugs used during pregnancy was classified for one or more instances of drug use at any time during pregnancy.
§Fetal weight for sex and gestation classified using customised fetal growth charts.28
¶Any respiratory support includes infants who were ventilated or received non-invasive respiratory support.
**Intra-cranial abnormality includes grade III or IV intra-ventricular haemorrhage, periventricular leukomalacia and grade II or III neonatal encephalopathy.
††Includes breast milk fed by any method. Data were missing for three mothers for gestational diabetes.
‡‡n (%) of infants with cognitive impairment where the obstetric/neonatal risk factor is present (column 2) and absent (column 3).
CRP, C-reactive protein; LMPT, late and moderately preterm.