Table 2.
Difference in mean (95% confidence interval) scores on British Ability Scales (BAS) with accumulating additional adjustment in study of effect of pregnancy planning and fertility treatment on cognitive development in children
| Model | Unplanned (n=1822, 15%) | Mistimed (n=3327, 26%) | Planned (n=6224, 53%) | Subfertile (480, 4%) | Induced ovulation (n=167, 1.4%) | ART (n=96, 1%) |
|---|---|---|---|---|---|---|
| Verbal abilities at age 3 (n=11 790)* | ||||||
| % missing data† | 4.5 | 52 | 3.5 | 3.4 | 2.4 | 4.0 |
| Unadjusted model | −4.8‡ (−6.0 to −3.7) | −2.4‡ (−3.4 to −1.5) | Reference | 1.1 (−0.7 to 2.9) | 0.2 (−2.8 to 3.1) | 3.8 (−0.2 to 7.9) |
| Plus a priori confounders§ | −5.3‡ (−6.4 to −4.3) | −2.8‡ (−3.7 to 2.0) | 0.7 (−1.0 to 2.5) | −0.3 (−3.2 to 2.5) | 4.1‡ (0.8 to 7.5) | |
| Plus sociodemographic factors | −0.9 (−1.9 to 0.2) | −0.4 (−1.2 to 0.4) | 0.3 (−1.5 to 2.1) | −2.3 (−5.0 to 0.5) | 1.2 (−2.0 to 4.4) | |
| Plus early life course factors | −0.8 (−1.8 to 0.3) | −0.3 (−1.1 to 0.5) | 0.4 (−1.3 to 2.2) | −2.0 (−4.7 to 0.7) | 1.7 (−1.5 to 4.9) | |
| Plus later life course factors | −0.3 (−1.3 to 0.7) | −0.2 (−1.0 to 0.5) | 0.3 (−1.5 to 2.0) | −2.4 (−5.0 to 0.2) | 1.6 (−1.6 to 4.7) | |
| Verbal abilities at age 5 (n=12 136)¶ | ||||||
| % missing data† | 1.7 | 1.0 | 1.1 | 0.6 | 1.0 | 1.2 |
| Unadjusted model | −4.6‡ (−5.5 to −3.6) | −3.4‡ (−4.2 to −2.5) | Reference | 1.5‡ (0.1 to 3.0) | 4.5‡ (2.2 to 6.8) | 3.5‡ (0.2 to 6.8) |
| Plus a priori confounders§ | −4.9‡ (−5.8 to −4.0) | −2.9‡ (−3.7 to −2.2) | 1.4 (0.0 to 2.8) | 4.0‡ (1.7 to 6.3) | 4.8 (2.1 to 7.4) | |
| Plus sociodemographic factors | −0.2 (−1.2 to 0.7) | −0.2 (−0.9 to 0.6) | 1.0 (−0.4 to 2.4) | 2.0‡ (−0.1 to 4.2) | 2.0 (−0.7 to 4.8) | |
| Plus early life course factors | −0.2 (−1.1 to 0.7) | −0.2 (−0.9 to 0.5) | 1.2 (−0.2 to 2.6) | 2.2‡ (0.1 to 4.3) | 2.3 (−0.5 to 5.1) | |
| Plus later life course factors | −0.1 (−1.0 to 0.8) | −0.2 (−0.9 to 0.5) | 1.1 (−0.3 to 2.5) | 2.1 (0.0 to 4.2) | 2.2 (−0.6 to 5.0) | |
| Non-verbal abilities at age 5 (n=12 176)** | ||||||
| % missing data† | 1.4 | 1.0 | 0.9 | 0.6 | 1.0 | 0.3 |
| Unadjusted model | −1.9‡ (−2.7 to −1.1) | −1.8‡ (−2.4 to −1.6) | Reference | −0.1 (−1.2 to 1.1) | −1.1 (−3.1 to 0.9) | −1.2 (−4.1 to 1.8) |
| Plus a priori confounders§ | −2.0‡ (−2.8 to −1.2) | − 1.8‡ (−2.4 to −1.2) | −0.2 (−1.3 to 1.0) | −1.1 (−3.1 to 0.9) | −0.8 (−3.7 to 2.1) | |
| Plus sociodemographic factors | −0.3 (−1.1 to 0.5) | −0.6‡ (−1.2 to 0.0) | 0.0 (−1.2 to 1.1) | −1.6 (−3.6 to 0.3) | −1.4 (−4.2 to 1.5) | |
| Plus early life course factors | −0.2 (−1.0 to 0.6) | −0.6 (−1.2 to 0.0) | 0.1 (−1.1 to 1.2) | −1.5 (−3.5 to 0.4) | −1.2 (−4.1 to 1.6) | |
| Plus later life course factors | −0.2 (−1.0 to 0.6) | −0.6 (−1.2 to 0.0) | 0.1 (−0.1 to 1.2) | −1.5 (−3.5 to 0.4) | −1.2 (−4.1 to 1.6) | |
| Spatial abilities at age 5 (n=11 206)†† | ||||||
| % missing data† | 1.8 | 1.3 | 1.2 | 0.6 | 1.0 | 0.3 |
| Unadjusted model | −4.5‡ (−5.8 to −3.1) | −2.7‡ (−3.7 to −1.8) | Reference | 0.5 (−1.4 to 2.3) | 0.7 (−2.9 to 4.3) | −3.3 (−7.9 to 1.3) |
| Plus a priori confounders§ | −4.7‡ (−6.0 to −3.3) | −2.9‡ (−3.9 to −2.0) | 0.2 (−1.6 to 2.0) | 0.5 (−2.9 to 4.0) | −2.7 (−7.1 to 1.7) | |
| Plus sociodemographic factors | −1.0 (−2.3 to 0.3) | −0.7 (−1.6 to 0.2) | 0.6 (−1.1 to 2.4) | −0.2 (−3.7 to 3.3) | −3.2 (−7.3 to 1.0) | |
| Plus early life course factors | −0.9 (−2.2 to 0.4) | −0.6 (−1.5 to 0.3) | 1.0 (−0.8 to 2.7) | 0.2 (−3.2 to 3.5) | −2.5 (−6.7 to 1.8) | |
| Plus later life course factors | −0.8 (−2.1 to 0.5) | −0.6 (−1.6 to 0.3) | 0.9 (−0.9 to 2.7) | 0.0 (−3.4 to 3.3) | −2.7 (−6.9 to 1.6) | |
*Additional adjustments: sociodemographic—maternal age, social class, income, qualifications, first born; early life course—birth weight, breast feeding; later life course—maternal positive relationship score, maternal involvement score, age started childcare.
†% of children eligible for inclusion in analysis who do not have BAS score. % weighted for design effects only, not for non-response.
‡P<0.05 (significant).
§A priori confounders were age at sweep, language (English only, English and another), sex of cohort member.
¶Additional adjustments: sociodemographic—maternal age, social class, income, family structure, qualifications, first born, alcohol in pregnancy, smoking in pregnancy, father’s qualifications; early life course—birth weight, breast feeding; later life course—maternal involvement.
**Additional adjustments: sociodemographic—social class, income, qualifications, father’s age, father’s qualifications; early life course—birth weight, breast feeding; later life course—maternal involvement, childcare (any, informal, formal).
††Additional adjustments: sociodemographic—social class, income, qualifications, alcohol in pregnancy, father’s qualifications; early life course—gestation, birth weight, breast feeding; later life course—maternal involvement, maternal discipline, schooling (full time, part time).