Baseline characteristics of study participants with and without co-occurrence*
| Co-occurrence N=100 | No co-occurrence N=1341 | p Value | |
|---|---|---|---|
| Gestational age (weeks) | 35.3 (SD 2.4) | 36.1 (SD 2.9) | 0.004 |
| Birth weight (g) | 2517 (SD 619) | 2747 (SD 800) | 0.005 |
| Age of child CBCL (months)† | 45.0 (SD 1.7) | 44.8 (SD 4.3) | 0.62 |
| Age of child ASQ (months)† | 45.0 (SD 1.3) | 45.2 (SD 1.4) | 0.19 |
| Gestational age (cohort) | 0.002 | ||
| Full-term | 23.0% (23) | 38.4% (515) | |
| Moderate/late preterm, total | 77.0% (77) | 61.6% (826) | |
| 32 weeks | 6.0% (6) | 7.4% (99) | |
| 33 weeks | 18.0% (18) | 12.0% (161) | |
| 34 weeks | 18.0% (18) | 17.4% (233) | |
| 35 weeks | 35.0% (35) | 24.8% (333) | |
| SGA‡ | 11.0% (11) | 8.6% (115) | 0.41 |
| Male gender | 75.0% (75) | 52.6% (705) | <0.001 |
| Part of multiple birth | 17.0% (17) | 18.5% (249) | 0.50 |
| One-parent family | 8.1% (8/99) | 5.6% (74/1333) | 0.30 |
| Number of siblings | 0.09 | ||
| 0 | 12.0% (12) | 16.8% (225) | |
| 1 | 51.0% (51) | 54.9% (736) | |
| 2 | 24.0% (24) | 21.4% (287) | |
| ≥3 | 13.0% (13) | 6.9% (93) | |
| Maternal age (years) | 0.003 | ||
| <25 | 16.0% (16) | 6.8% (88/1301) | |
| 25–34 | 66.0% (66) | 73.4% (955/1301) | |
| >34 | 18.0% (18) | 19.8% (258/1301) | |
| Socioeconomic status§ | 0.002 | ||
| Low | 25.0% (25) | 17.2% (231) | |
| Medium | 69.0% (69) | 63.2% (847) | |
| High | 6.0% (6) | 19.6% (263) | |
| Maternal ethnicity | 0.002 | ||
| The Netherlands | 87.0% (87) | 95.2% (1262/1325) | |
| Europe | 4.0% (4) | 1.5% (20/1325) | |
| Non-European country | 9.0% (9) | 3.2% (43/1325) |
Data are mean (SD) or % (n).
*Co-occurrence of developmental delay (ASQ total or domain score >2 SD below the mean) and emotional/behavioural problems (CBCL score >84th percentile for total, internalising or externalising problems).
†Age at completing the CBCL and the ASQ, respectively.
‡SGA, small for gestational age: birth weight below the 10th percentile of the Dutch Kloosterman growth charts.
§Socioeconomic status: composite measure of parental education, occupation and family income (standardised score with categories >1 SD below the mean, the mean±1 SD, and above the mean+1 SD).
ASQ, Ages and Stages Questionnaire; CBCL, Child Behaviour Checklist.