Table 5 Association between low and very low birth weight and features of depression and bipolar disordera
Low birth weightVery low birth weight
Relative risk ratios (95% CI)PRelative risk ratios (95% CI)POverall dose P
 Unadjusted (n=83 127)1.11 (1.06–1.15)<0.0011.32 (1.20–1.46)<0.001<0.001
 Adjusted for potential confoundersb (n=71 591)1.06 (1.02–1.11)0.0071.24 (1.11–1.37)<0.001<0.001
 Adjusted for potential physical disease mediatorsc(n=71 591)1.05 (1.00–1.09)0.0411.19 (1.07–1.33)0.0010.001
Bipolar disorder
 Unadjusted (n=83 545)1.13 (0.91–1.41)0.2721.64 (1.00–2.67)0.0490.048
 Adjusted for potential confoundersb (n=71 935)1.13 (0.89–1.44)0.3321.74 (1.05–2.87)0.0320.047
 Adjusted for potential physical disease mediatorsc(n=71 935)1.10 (0.86–1.40)0.4361.63 (0.98–2.69)0.0580.089
  • a All risk ratio statistics are relative to the normal birth weight group, except for the overall dose P-value which refers to an ordinal dose effect (i.e. very low>low>normal birth weight).

  • b Adjusted for year of birth, Townsend deprivation score, ethnicity, gender, maternal smoking and maternal depression.

  • c Additonally adjusted for hypertension, heart/cardiac problems, stroke, perivascular disease, type 2 diabetes, chronic obstructive pulmonary disease and osteoporosis.