Objective. To describe patterns of vaginal bleeding in the first 20 weeks of pregnancy and evaluate the association between patterns of bleeding and risk of subsequent pre-eclampsia in nulliparous women. Design. Cohort study. Setting. Participating centres of the Screening for Pregnancy Endpoints (SCOPE) study in Auckland (New Zealand), Adelaide (Australia), Manchester and London (UK) and Cork (Ireland). Population. Healthy nulliparous women (n= 3431). Methods. Logistic regression was used to assess the association between bleeding characteristics and pre-eclampsia while controlling for known determinants of pre-eclampsia. Main outcome measures. Preeclampsia, defined as gestational hypertension with proteinuria or any multi-system complication of preeclampsia. Four bleeding variables were evaluated: any bleeding during the first 20 weeks; maximal bleeding intensity; duration of bleeding; and number of bleeding episodes. Results. Of the 3431 women enrolled, 780 (23%) experienced vaginal bleeding during the first 20 weeks of pregnancy. Risk of pre-eclampsia was not associated with the presence or absence of bleeding (adjusted odds ratio (ORa) 0.96, 95% confidence interval (95% CI) 0.67–1.38). Analyses confined to women with vaginal bleeding showed that any bleeding episode of five or more consecutive days, compared with shorter episodes, increased risk of pre-eclampsia approximately twofold (ORa 2.15, 95% CI 1.01–4.57), as did multiple compared with single episodes of bleeding (ORa 2.33, 95% CI 1.16–4.67). Conclusions. Bleeding is a common complication during the first 20 weeks of nulliparous pregnancy, and the presence or absence of vaginal bleeding is not a determinant of subsequent pre-eclampsia. Among women with vaginal bleeding, consideration of the bleeding pattern, in terms of intensity, duration and frequency, appears to be informative with respect to pre-eclampsia risk.