Table 3

 Odds of being small or large for gestational age associated with maternal bipolar disorder and treatment with mood stabilisers during pregnancy compared with reference group of infants of mothers without bipolar disorder and not using mood stabilisers during pregnancy

VariablesNoSmall for gestational age*Large for gestational age*
%Univariate odds ratio (95% CI)Multivariate† odds ratio (95% CI)P value§%Univariate odds ratio (95% CI)Multivariate† odds ratio (95% CI)P value§
Birth weight:
 No bipolar disorder330 2312.31 (reference)1 (reference)0.462.31 (reference)1 (reference)0.25
 Untreated bipolar disorder5513.41.59 (1.01 to 2.51)1.41 (0.88 to 2.24)3.31.37 (0.86 to 2.19)1.43 (0.89 to 2.30)
 Treated bipolar disorder‡3192.51.14 (0.57 to 2.29)0.93 (0.46 to 1.88)3.11.30 (0.70 to 2.41)1.54 (0.83 to 2.87)
Birth length:
 No bipolar disorder328 1472.31 (reference)1 (reference)0.292.31 (reference)1 (reference)0.40
 Untreated bipolar disorder5503.81.75 (1.13 to 2.71)1.51 (0.97 to 2.34)1.60.71 (0.37 to 1.36)0.75 (0.39 to 1.45)
 Treated bipolar disorder‡3143.21.43 (0.77 to 2.67)1.15 (0.61 to 2.15)2.91.25 (0.65 to 2.40)1.44 (0.75 to 2.77)
Head circumference:
 No bipolar disorder324 8442.31 (reference)1 (reference)0.162.31 (reference)1 (reference)0.70
 Untreated bipolar disorder5423.91.77 (1.14 to 2.73)1.68 (1.07 to 2.62)3.01.25 (0.76 to 2.06)1.27 (0.77 to 2.10)
 Treated bipolar disorder‡3113.31.45 (0.78 to 2.71)1.26 (0.67 to 2.37)2.30.90 (0.39 to 2.07)0.97 (0.42 to 2.23)
Low birth weight and short length:
 No bipolar disorder327 5900.81 (reference)1 (reference)0.35
 Untreated bipolar disorder5471.82.24 (1.20 to 4.19)1.84 (0.97 to 3.53)
 Treated bipolar disorder‡3141.31.53 (0.57 to 4.07)1.14 (0.42 to 3.08)

*Small or large for gestational age were defined as being in ≤2.3 centile or ≥97.7 centile (2 standard deviations), respectively, of total population in cohort. Growth references for this calculation were from Marsal et al 199620 for birth weight and from Nicklasson et al 199121 for birth length and head circumference.

†Adjusted for birth order and for maternal age, country of birth, cohabitation, smoking, height, and diagnosis of alcohol or substance misuse disorder.

‡Filling a prescription with lithium, antipsychotics, carbamazepine, lamotrigine, or valproate during pregnancy.

§P value for overall analysis of variation in outcome between three exposure groups.