A widely used drug that acts as a mild central nervous, circulation and respiratory stimulant. There are some conflicting reports on whether or not caffeine consumption during pregnancy is safe or not, but consuming 800mg of caffeine, or about 4 cups of coffee, a day is associated with decreased birth weight, smaller head size, miscarriage, and premature labor. The more caffeine you consume the greater your risks. Caffeine crosses the placenta and can affect calcium metabolism and increase the risk of breathing problems in your newborn. Caffeine is also passed to your baby through breast milk, which causes irritability and sleeplessness in infants, so in 1980 the FDA advised pregnant women to limit their caffeine intake.