May 2, 2008 — Chocolate may decrease the risk for preeclampsia, according to the results of a prospective cohort study reported in the May issue of Epidemiology.

"Preeclampsia is a major pregnancy complication with cardiovascular manifestations," write Elizabeth W. Triche, PhD, from the Yale Center for Perinatal, Pediatric and Environmental Epidemiology in New Haven, Connecticut, and colleagues. "Recent studies suggest that chocolate consumption may benefit cardiovascular health."

The study sample used to evaluate the association of chocolate consumption with the risk for preeclampsia consisted of 2291 pregnant women who delivered a singleton live birth between September 1996 and January 2000.

The investigators measured chocolate consumption by self-report in the first and third trimesters and by umbilical cord serum concentrations of theobromine, which is the main methylxanthine component of chocolate. Detailed medical record review for 1943 of the women allowed determination of preeclampsia. Logistic regression models controlling for potential confounders were used to determine adjusted odds ratios (aOR) and 95% confidence intervals (CIs).

Of 1681 women, preeclampsia developed in 63 (3.7%). Umbilical cord serum theobromine concentrations were inversely associated with preeclampsia (for the highest vs the lowest quartile [aOR, 0.31; CI, 0.11 - 0.87]).

Self-reported estimates of chocolate consumption were also negatively associated with preeclampsia. The risk for preeclampsia was decreased for women consuming 5 or more servings per week vs women consuming less than 1 serving of chocolate weekly (aOR, 0.81; CI, 0.37 - 1.79 for consumption in the first 3 months of pregnancy and aOR, 0.60; CI, 0.30 - 1.24 in the last 3 months).

"Our results suggest that chocolate consumption during pregnancy may lower risk of preeclampsia," the study authors write. "However, reverse causality may also contribute to these findings."

Limitations of this study include difficulty standardizing self-reported chocolate consumption, possible reverse causality if women diagnosed with preeclampsia reduced their calorie intake after diagnosis, possible residual confounding by smoking or body mass index (BMI), small number of women with preeclampsia, and potential misclassification of exposure.

"Because of the importance of preeclampsia as a major complication of pregnancy, replication of these results in other large prospective studies with a detailed assessment of chocolate consumption is warranted," the study authors write. "Measurements of chocolate exposure should be designed to permit careful examination of the temporal relationship between chocolate consumption in pregnancy and subsequent risk of preeclampsia."

The National Institute on Drug Abuse supported this study.

Epidemiology. 2008;19:459-464.

Clinical Context

Study Highlights

• Pregnant women were recruited from September 1996 to January 2000 from 56 obstetric practices and 15 clinics associated with 6 hospitals in Connecticut and Massachusetts.
• Exclusion criteria were more than 24 weeks' gestational age at enrollment, insulin-dependent diabetes mellitus, non-English or Spanish-speaking women, or intention to terminate the pregnancy.
• Of 11,267 women screened for the study, 9576 met eligibility criteria, and 3631 women were invited to participate, of whom 2478 (68%) enrolled, 639 (18%) declined, 424 (12%) were lost to follow-up, 72 (2%) had a miscarriage before enrollment, and 20 (< 1%) were not eligible at enrollment interview.
• Of the 2478 enrolled women, 2291 (92%) delivered a singleton infant live birth.
• The investigators measured chocolate consumption by self-report in the first and third trimesters and by umbilical cord serum concentrations of theobromine (the main methylxanthine component of chocolate).
• Umbilical cord blood biomarker data were available for 1611 infants, 1995 women provided data on both first-trimester and third-trimester chocolate consumption, and preeclampsia status was determined for 1943 women from detailed medical record review.
• Logistic regression models controlling for potential confounders were used to determine aORs and 95% CIs.
• Reported chocolate consumption was high, particularly in the third trimester.
• Women who reported consuming more chocolate tended to be younger, less well educated, Hispanic, women who smoked during pregnancy, and women receiving prenatal care in clinics.
• Of 1681 women, preeclampsia developed in 63 (3.7%).
• Higher BMI, education, and nulliparity were most strongly associated with increased risk for preeclampsia.
• Umbilical cord serum theobromine concentrations were negatively associated with preeclampsia (for the highest vs the lowest quartile [aOR, 0.31; CI, 0.11 - 0.87]).
• Self-reported estimates of chocolate consumption were also negatively associated with preeclampsia.
• The risk for preeclampsia was decreased for women consuming 5 or more servings of chocolate per week in the first 3 months of pregnancy vs women consuming less than 1 serving of chocolate weekly (aOR, 0.81; CI, 0.37 - 1.79).
• The risk for preeclampsia was also decreased for women consuming 5 or more servings of chocolate per week in the last 3 months of pregnancy vs women consuming less than 1 serving of chocolate weekly (aOR, 0.60; CI, 0.30 - 1.24).
• Limitations of this study include difficulty standardizing self-reported chocolate consumption, possible reverse causality, possible residual confounding by smoking or BMI, small number of women with preeclampsia, and potential misclassification of exposure.
• Based on these findings, the investigators concluded that chocolate consumption during pregnancy may lower the risk for preeclampsia.
• However, they recommend replication of these results in other large, prospective studies with a detailed evaluation of chocolate consumption, including the temporal relationship between chocolate consumption in pregnancy and subsequent preeclampsia.

Pearls for Practice

• In this prospective cohort study of pregnant women, concentrations of umbilical cord serum theobromine, a marker for chocolate consumption, were negatively associated with preeclampsia.
• Self-reported estimates of chocolate consumption were also negatively associated with preeclampsia in this study. The risk for preeclampsia was decreased by 19% for women consuming 5 or more servings per week vs women consuming less than 1 serving of chocolate weekly in the first 3 months of pregnancy. The risk for preeclampsia was decreased by 40% for women consuming 5 or more servings per week in the last 3 months of pregnancy vs women consuming less than 1 serving of chocolate weekly.

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