http://www.ncbi.nlm.nih.gov/pubmed/22502981

J Matern Fetal Neonatal Med. 2012 May;25(5):528-30.

The effects of maternal caffeine and chocolate intake on fetal heart rate.

Buscicchio G, Piemontese M, Gentilucci L, Ferretti F, Tranquilli AL.

Source

Department Clinical Sciences, Università Politecnica Marche , Ancona , Italy.

Abstract

Objective: 

The aim of our study was to analyze the effects of caffeine and chocolate (70% cocoa) on fetal heart rate (FHR). 

Study design: 

Fifty pregnant women with uncomplicated gestation, matched for age and parity, underwent computerized FHR recording before and after the consumption of caffeine and then, after one week, before and after 70% cocoa chocolateintake. Computerized cardiotocography (cCTG) parameters were expressed as mean and SD. The differences were tested for statistical significance using the paired t-test, with significance at p < 0.05. 

Results: 

The number of uterine contraction peaks, the number of small and large accelerations (10 and 15 beats per minute for 15 seconds), the duration of episodes of high variation and the short-term FHR variation were significantly higher (p < 0.001) after maternal coffee intake. The number of large accelerations, the duration of episodes of high variation and the short-term FHR variation were significantly higher (p < 0.001) after maternal consumption of chocolate, whilst no effect of cocoa was found during contractions. 

Conclusions: 

Our results suggest that maternal intake of both caffeine and 70% cocoa have a stimulating action on fetal reactivity. This finding is likely due to the pharmacological action of theobromine, a methilxanthine present in coffee and in chocolate. The correlation between maternal caffeine intake and increased uterine contraction peaks is likely due to the effect of caffeine on the uterine muscle.