# Table 3 Univariate associations of predictors with the rate of positive and negative interaction scores

Summary statistics for predictor* Associations with rate of negative interactions Associations with rate of positive interactions
Child gender Female 49 (30.6%) - -
Male 111 (69.4%) 1.71 (0.81, 3.62), p = 0.160 0.89 (0.74, 1.06), p = 0.202
Mother age at birth (for 1 year increase)   29.5 (4.5) 0.90 (0.83, 0.97), p = 0.004 1.02 (1.00, 1.04), p = 0.033
Parity (per unit increase)   0.7 (0.8) 0.87 (0.56, 1.36), p = 0.550 0.97 (0.88, 1.08), p = 0.584
Maternal depression at 32--40 weeks (per unit increase)   6.9 (5.0) 1.01 (0.94, 1.08), p = 0.812 1.01 (1.00, 1.03), p = 0.118
Postnatal depression at 8 months (per unit increase)   5.6 (5.0) 1.03 (0.97, 1.10), p = 0.354 1.01 (0.99, 1.02), p = 0.478
Maternal anxiety at 32--40 weeks (per unit increase)   4.7 (3.4) 1.03 (0.93, 1.14), p = 0.630 1.02 (0.99, 1.04), p = 0.153
Postnatal anxiety at 8 months (per unit increase)   3.8 (3.9) 1.00 (0.92, 1.10), p = 0.934 1.01 (0.99, 1.04), p = 0.172
Infant breast fed No 24 (15.1%) - -
Yes 135 (84.9%) 1.26 (0.47, 3.36), p = 0.649 1.19 (0.94, 1.51), p = 0.150
Marital status Never married 22 (13.8%) - -
1st marriage 123 (77.4%) 1.09 (0.40, 2.97), p = 0.873 1.27 (1.00, 1.63), p = 0.054
2nd/3rd marriage 9 (5.7%) 1.03 (0.18, 5.82), p = 0.970 1.25 (0.82, 1.90), p = 0.292
Divorced 5 (3.1%) 0.66 (0.07, 6.16), p = 0.718 1.34 (0.80, 2.24), p = 0.264
Father in household No 14 (9.2%) - -
Yes 139 (90.8%) 0.50 (0.15, 1.63), p = 0.251 1.20 (0.89, 1.62), p = 0.225
Maternal education levels Vocational/CSE/GCSE 89 (56.0%) - -
A level/Degree 70 (44.0%) 1.02 (0.51, 2.04), p = 0.958 1.32 (1.12, 1.55), p = 0.001
Anyone with chronic illness in household No 133 (88.7%) - -
Yes 17 (11.3%) 1.11 (0.36, 3.42), p = 0.861 0.89 (0.68, 1.16), p = 0.389
Smoked during first trimester No 128 (81.0%) - -
Yes 30 (19.0%) 0.64 (0.26, 1.58), p = 0.331 0.91 (0.73, 1.13), p = 0.384
Alcohol during first trimester (glasses of alcohol per week) < 1 129 (81.6%) - -
≥ 1 29 (18.4%) 1.04 (0.43, 2.52), p = 0.929 1.04 (0.84, 1.29), p = 0.737
Partner physically hurt mother at 18 weeks gestation No 143 (93.5%) - -
Yes 10 (6.5%) 1.29 (0.32, 5.17), p = 0.718 1.03 (0.72, 1.46), p = 0.880
Partner physically hurt mother postnatally No 152 (95.0%) - -
Yes 8 (5.0%) 0.34 (0.06, 1.97), p = 0.230 1.01 (0.69, 1.47), p = 0.962
Social support score (per unit increase)   20.1 (4.8) 0.94 (0.87, 1.01), p = 0.072 1.01 (0.99, 1.03), p = 0.335
Life event score 18--23 weeks (per unit increase)   8.6 (6.5) 1.02 (0.97, 1.08), p = 0.417 1.00 (0.98, 1.01), p = 0.716
Maternal bonding score (per unit increase)   28.0 (4.0) 0.98 (0.91, 1.07), p = 0.723 0.98 (0.96, 1.00), p = 0.024
Aggression score (per unit increase)   10.2 (1.8) 0.96 (0.78, 1.17), p = 0.655 1.03 (0.98, 1.08), p = 0.300
1. (Effect estimates are the relative change in interaction scores for a specified increase in continuous predictor variables or compared to the stated reference group for categorical predictors).
2. *Mean (SD) presented for continuous variables and N (%) for categorical.
3. - indicates reference category in regression analysis.
4. Statistically significant associations (p<0.05) are highlighted in bold text.