Breastfeeding is good for both mother and baby for the following reasons: Breastfeeding triggers the release of a hormone called oxytocin that causes the uterus to contract. This helps the uterus return to its normal size more quickly and may decrease the amount of bleeding after giving birth. Breast-feeding may make it easier to lose weight gained during pregnancy. Breastfeeding may reduce the risk of breast cancer and ovarian cancer.
Drinking caffeine is moderate amounts (200 mg a day) most likely will not affect the baby. Newborns and preterm infants are more sensitive to caffeine's effects. Consume a lower amount of caffeine in the first few days after birth or if breastfeeding a preterm baby. Wait at least 2 hours after an occasional, single, alcoholic drink to breastfeed. The alcohol will leave your bloodstream - there is no need to express and discard your milk. Drinking more than two drinks per day, especially on a regular basis is not recommended.
Most medications are safe while breastfeeding. Although medications can be passed through the milk. However, the levels are usually very low. The latest information about medications and their effects on breastfed babies can be found at LactMed a database of scientific information, at www.toxnet.nim.nih.gov/newtoxnet/lactmed.htm