Univariate regression analysis—effect on cord anti-PT IgG titres >20 IU/mL
| Variable | OR (95% CI) | P value |
| Maternal age | 1.60 (0.88 to 2.91) | 0.118 |
| Vaccinated in pregnancy | 0.80 (5.54 to 17.35) | <0.001* |
| Maternal seropositivity | 41.04 (17.52 to 96.11) | <0.001* |
| Term gestational age | 2.58 (1.32 to 5.05) | 0.005* |
| Birth weight | 2.26 (1.10 to 4.67) | 0.026* |
*P<0.05 considered significant
anti-PT, anti-pertussis toxin.