Prevalence and severity of nausea and vomiting of pregnancy and effect of vitamin supplementation

Objective: Although nausea and vomiting of pregnancy is the most common med ical condition during pregnancy, there are many unanswered questions regard ing its cause, epidemiologic features and optimal management. The objective s of this study were to ascertain the prevalence of nausea and vomiting in a sample of Canadian women, to characterize the distribution of their sever ity and to investigate the role of vitamin B-6 deficiency in their etiology . Design: Prospective study. Setting: Antenatal counselling service for pregnant women. Patients: Three cohorts of women: a prospective, population-based cohort of 193 women, to estimate the rate and severity of nausea and vomiting (cohor t A); a cohort of 555 women who sought advice for nausea with or without vo miting, to study the correlation between the maximal daily number of episod es of vomiting and maximal weight loss (cohort B); and a prospective cohort of 301 women who reported vomiting, to correlate vitamin supplementation w ith vomiting (cohort C). Interventions: All 3 cohorts were interviewed during the counselling sessio n, and cohort B was followed up prospectively. Outcome measures: Frequency of nausea and vomiting, weight loss, maximal nu mber of daily episodes of vomiting, rate of multivitamin supplementation. Results: Overall, 67% of the women in cohort A reported experiencing nausea or vomiting, or both; 22% reported vomiting, and 9% experienced weight los s. In cohort B there was a significant correlation between the maximal numb er of daily episodes of vomiting and maximal weight loss, although there wa s wide variation (r(2) = 0.25, p < 0.001). There was a highly significant c orrelation between the number of daily vomiting episodes and mean weight lo ss (r(2) = 0.99). In cohort C, vomiting was significantly associated with l ack of supplementation with multivitamins before 6 weeks' gestation (p = 0. 002). Conclusions: The relation between number of daily vomiting episodes and mea n weight loss may serve as a clinical tool to assess the severity of nausea and vomiting in pregnancy and the success of anti-emetics and rehydration regimens. Further study is needed to elucidate the biologic basis of the ob served association between vomiting and lack of multivitamin supplementatio n in early pregnancy.