Caffeine and pregnancy
Caffeine in relation to pregnancy
Drinking more than five cups of coffee a day during pregnancy is associated with an increased risk of spontaneous abortion. However, that the moderate consumption of caffeine is unlikely to increase miscarriage. The researchers measured a biological marker, serum paraxanthine (a metabolite of caffeine) in women who had spontaneous abortions at less than 140 days’ gestation and in matched women who gave birth to live infants. The mean serum paraxanthine concentration was higher in the women who had had a miscarriage than in the controls. Women whose paraxanthine levels were equivalent to consumption of five or more cups of coffee a day were more than twice as likely to miscarry as those with lower paraxanthine levels.
Investigations based on evaluation of coffee consumption on serum levels of paraxanthine, a metabolite of caffeine, have suggested that a high level of caffeine intake is a moderate risk factor for spontaneous abortion.There is a significantly increased risk of fetal death among people who consume caffeine during pregnancy compared with no caffeine consumption during pregnancy. 
High caffeine consumption was associated with low birth weight and/or prematurity.  Same time some other scientific experiments suggests that there is no such connection with normal low amount of caffeine intake.
Heavy coffee consumption (≥4 cups/day) was inversely associated with the occurrence of a recognized Down syndrome pregnancy, suggesting that mothers who consumed caffeine at levels of ≥400 mg/day are more likely to miscarry a Down syndrome fetus. 
15. Matijasevich A et al, Maternal caffeine consumption and foetal death. 2006; 20(2), 100-9
16. Pacheco AH et al, Caffeine consumption during pregnancy and prevention of low birth weight and prematurity. 2007; 12, 2807-19
17. Claudine P Torfs, Roberta E Christianson, Effect of maternal smoking and coffee consumption on the risk of having a recognized Down syndrome pregnancy. 2000; 152, 1185-91