Caffeine can worsen this situation. In addition to blood pressure problems, both increase stomach acid production. Coffee and smoking are a frequent, but unhealthy, combination. Limited research links heavy coffee drinking with heart attacks. Caffeine can produce heart rhythm problems, a temporary rise of blood pressure, and those subject to irregular heartbeats should avoid caffeine.
Caffeine enters the bloodstream and passes through the placental barrier to the fetus.
Pregnant women should check with their doctor before taking any drug, including nonprescription medications, many of which contain caffeine. Caffeine can be passed to infants in the breast milk of mothers who ingest caffeine. No study indicates its harm, but it may have marked effects on an infant's behavior, leading to sleep disruptions and irritability. Caffeine acts upon the brain and may affect coordination, sleep patterns and behavior. Caffeine may aggravate such existing problems as ulcers, stomach upset and indigestion, and can have a laxative effect.