The widespread use of caffeine justifies its being thoroughly investigated for signs of any adverse effects it might have in relation to human reproduction. The present review surveys a range of potential adverse influences of caffeine, including its pharmacological effects on the fetus and neonate, its teratogenicity, its possible effect on intrauterine growth, and its possible involvement in reproductive loss. While evidence of adverse effects does exist, the quality of the research conducted to date does not permit any firm conclusions. In general, the relevant research has been characterized by significant methodological inadequacies, including: extensive reliance on retrospective questionnaire and/or interview data; inadequate control and quantification of the independent variable of caffeine use; lack of control over potentially confounding factors (especially alcohol and nicotine use); and the absence of adequate control groups.