>The results of this literature review suggest that heavy caffeine use (≥ 300 mg per day) during pregnancy is associated with small reductions in infant birth weight that may be especially detrimental to premature or low-birth-weight infants. Some researchers also document an increased risk of spontaneous abortion associated with caffeine consumption prior to and during pregnancy. However, overwhelming evidence indicates that caffeine is not a human teratogen, and that caffeine appears to have no effect on preterm labor and delivery.