Dark green poop in a four-month-old baby may be a normal physiological phenomenon; it may also be an abnormal phenomenon caused by enteritis, indigestion and other diseases. 1. Physiological phenomenon: four-month-old baby dark green poop, but the baby’s growth and development, weight gain, milk intake, mental state, general conditions are not abnormal, this is considered to be a physiological phenomenon, generally do not need special treatment. The baby mother pay attention to the light and easy to digest food as the main. 2. Enteritis: If the baby’s intestinal tract is inflamed, due to the stimulation of inflammation, it may also lead to dark green poop, and you need to take your child to the hospital. 3. Indigestion: If you breastfeed your baby too much, or if your belly gets cold, you may suffer from indigestion, which may lead to dark green poop. There are other reasons why a four-month-old baby may have dark green poop, so it is recommended that you take your baby to the hospital in a timely manner.