Background: This study evaluated the effect of caffeine consumption on the success rate of pregnancy and various in vitro fertilization (IVF) performance parameters.
Material/Methods: Serum and follicular fluid samples were collected from 619 women undergoing IVF treatment (2002–2003). Caffeine assessment was based on measuring the levels of caffeine in serum and follicular fluid and on the number of coffee or tea or caffeinated drinks consumed per day.
Results: A total of 97.3% of participants reported the consumption of caffeinated drinks such as coffee, tea and soft drinks. Their average caffeine consumption was 455.82 mg/day (range: 3.71–3561 mg/day). Coffee was the primary source of caffeine intake. The average caffeine levels in serum (0.913 µg/ml) were significantly higher than in follicular fluid (0.701 µg/ml). After controlling for various potential confounding variables, no association was found between coffee or tea consumption and the success rate of pregnancy. Looking at the effect of caffeine consumption on the IVF performance parameters, we found that the number of eggs decreased as the caffeine serum levels increased (P=0.011). An increase in coffee consumption was positively associated with the number of aborted pregnancy (P=0.007), while the number of good embryo decreased with high tea consumption (P=0.015).
Conclusions: Though no association was seen between coffee or tea consumption and pregnancy rate, this study is the first to report that caffeine can reach the follicular fluid and there is a suggestive evidence of its possible harmful role on the consequences of reproductive process. This clearly warrants further investigation.

Keywords: Odds Ratio, Gas Chromatography-Mass Spectrometry, Follicular Fluid - chemistry, Fertilization in Vitro - statistics & numerical data, Coffee, Central Nervous System Stimulants - pharmacology, Caffeine - pharmacology, Abortion, Spontaneous - chemically induced, Pregnancy, Pregnancy Outcome, Regression Analysis, Saudi Arabia, Tea