Consumption of chocolate in pregnant women and risk of preeclampsia: a systematic review.

Previous studies have been limited in reporting the association between chocolate consumption, measured by interviewer-administered questionnaire or serum theobromine, a biomarker for cocoa, and risk of preeclampsia, and have showed somewhat conflicting results. A systematic review of observational and experimental studies will be carried out. We will examine PubMed, Embase, and the entire Cochrane Library. Studies of chocolate consumption compared or not with placebo or low flavanol chocolate during pregnancy will be evaluated to investigate the effect of chocolate consumption in pregnant women on the risk of preeclampsia or pregnancy-induced hypertension. Screening for inclusion, data extraction, and quality assessment will be performed independently by two reviewers in consultation with a third reviewer. Validity of the studies will be ascertained by using the Cochrane Collaboration's tool. Relative risk of preeclampsia will be the primary measure of treatment effect. Heterogeneity will be explored by subgroup analysis according to confounding factors and bias. This systematic review will contribute to establish the current state of knowledge concerning the possible association between chocolate consumption and prevention of preeclampsia. Furthermore, it will justify if additional experimental trials are necessary to better evaluate the benefits of chocolate consumption on the risk of preeclampsia. This systematic review has been registered in the PROSPERO international prospective register of systematic reviews. The registration number is: CRD42013005338.