It has been hypothesised that paraoxonase genes would be related to adverse pregnancy outcomes, via a maternal or fetal effect on placental hypoperfusion and thrombosis. To date only two studies have assessed this possibility. In this study we assessed the associations of the PON1 Q192R polymorphism with self-report of having pregnancy-induced hypertension, gestational hyperglycaemia and a preterm offspring birth. The associations were assessed in 3266 white women who were randomly selected from 23 British towns. There was no association between PON1 Q192R and either self-report of pregnancy-induced hypertension or gestational hyperglycaemia but the prevalence of reporting having a preterm birth increased with each R allele: per allele odds ratio 1.20 [95% confidence interval (CI) 1.03, 1.41]. When our results were pooled with the one previous study of the association of this polymorphism with preterm birth, the pooled per allele odds ratio was 1.19 [95% CI 1.02, 1.39]. Our findings provide some further evidence to suggest that PON1 Q192R is associated with preterm birth; they invite further investigation of both maternal and fetal genotype for PON1 Q192R in relation to preterm birth.