Table 4.
Discordant sibling pair analyses: fixed effects estimates of maternal cortisol in quintiles on full-scale, verbal and performance IQ [n = 74 pairs (148 individuals)]
| Full-scale IQ |
Verbal IQ |
Performance IQ |
|
|---|---|---|---|
| Free cortisol | β (95% CI) | β (95% CI) | β (95% CI) |
| Unadjusted | |||
| Lowest quintile | Reference | Reference | Reference |
| Second | −0.89 (−5.72 to 3.93) | −2.35 (−7.41 to 2.72) | 0.94 (−5.08 to 6.96) |
| Third | −1.96 (−7.57 to 3.65) | −1.77 (−7.66 to 4.12) | −1.80 (−8.80 to 5.20) |
| Fourth | −0.11 (−6.09 to 5.89) | −0.12 (−6.40 to 6.17) | 0.17 (−7.29 to 7.64) |
| Highest quintile | −2.77 (−9.06 to 3.53) | −6.78 (−13.39 to −0.17) | 2.36 (−5.50 to 10.21) |
| Adjusteda | |||
| Lowest quintile | Reference | Reference | Reference |
| Second | −0.83 (−6.04 to 4.36) | −2.07 (−7.55 to 3.41) | 0.80 (−5.72 to 7.63) |
| Third | −2.30 (−8.16 to 3.56) | −1.85 (−8.02 to 4.31) | −2.27 (−9.62 to 5.07) |
| Fourth | 0.03 (−6.29 to 6.36) | 0.63 (−6.04 to 7.29) | −0.30 (−8.23 to 7.64) |
| Highest quintile | −2.40 (−9.33 to 4.54) | −6.00 (−13.31 to 1.30) | 2.25 (−6.45 to 10.95) |
aThese models are adjusted for maternal age at birth, work status, birth order, anaemia and smoking during pregnancy and child sex.