What are the effects of caffeine on fetal development?

Probably none: Caffeine in moderation such as two cups of coffee a day is ok in pregnancy. The limited studies suggesting a negative relationship between caffeine intake and pregnancy were either done on animals who were given massive amounts of caffeine or on small numbers of actual patients wherre any real relationship was never conclusively shown.

Great question!: Caffeine crosses the placenta and may have fetal effects - including proarrhythmic tendency in the fetal heart and untold consequences in fetal brain development. Consumption in moderation is not contraindicated during pregnancy, however studies are lacking to assess your excellent question, namely what effect that has on the infant's character and neurolodevelopmental outcome, if any.