Table 2 Associations of maternal age at pregnancy with adolescent cognitive development and emotional and behavioural problems in a birth cohort in rural Western China. Higher scores indicated better cognitive development and worse emotional and behavioural problems

FSIQ

 n

1897

561

504

428

404

 Mean (SD)

97.4(12.1)

96.3(12.1)

99.0(12.1)

97.1(12.4)

97.3(11.6)

 Adjusted mean differences (95% CI) ^a

0.29(0.06, 0.52)

Reference

1.07(-0.35, 2.48)

1.66(-0.23, 3.56)

3.53(1.01, 6.06)

 P value for linear trend

0.015

0.009

Total behavioural problem score

 n

1897

561

504

428

404

 Mean (SD)

49.5(25.5)

49.6(26.0)

48.3(24.9)

49.3(24.7)

51.1(26.5)

 Adjusted mean differences (95% CI) ^a

-0.08(-0.63, 0.46)

Reference

-0.88(-4.18, 2.41)

-2.68(-7.10, 1.74)

-2.03(-7.93, 3.87)

 P value for linear trend

0.765

0.369

Internalizing behavioural problem score

 n

1897

561

504

428

404

 Mean (SD)

11.3(8.0)

11.2(8.3)

11.1(8.0)

11.0(7.5)

12.0(8.2)

 Adjusted mean differences (95% CI) ^a

0.02(-0.16, 0.19)

Reference

-0.88(-4.18, 2.41)

-2.68(-7.10, 1.74)

-2.03(-7.93, 3.87)

 P value for linear trend

0.863

0.561

Externalizing behavioural problem score

 n

1897

561

504

428

404

 Mean (SD)

8.6(7.5)

8.5(7.5)

8.3(7.2)

8.7(7.3)

9.2(7.8)

 Adjusted mean differences (95% CI) ^a

-0.01(-0.17, 0.15)

Reference

-0.16(-1.12, 0.80)

-0.72(-2.00, 0.56)

-0.67(-2.38, 1.05)

 P value for linear trend

0.898

0.364