Newborns feel pain, and pain early in life can change how the nervous system responds to pain later.

Epigenetic changes may help explain how early experiences affect us later in life.

Pain relief and comfort during medical procedures early in life may reduce the effects of harm later in life.

Several years ago, I worked with a woman who experienced trauma on the first day of her life. She was born with Rh incompatibility, a potentially deadly condition that occurs when an Rh-negative mother carries an Rh-positive baby and her immune system attacks the baby's red blood cells. This woman required a blood transfusion in which all of the blood in her body was drained and was replaced with transfused blood. This medical procedure saved her life, but she is experiencing lasting psychological adverse effects from the trauma associated with this procedure.

As a medical student, I remember watching an infant with his arms and legs strapped down to a board in order for the doctor to perform a circumcision. As the baby cried and screamed, the doctor performing the procedure said that the young boy would not remember this procedure years later. No anesthesia was used. Was the doctor correct? I have wondered about this for more than 40 years, and I can tell you that my research into epigenetic memory has taught me that he was probably wrong.

As a father, I took my 2-year-old daughter to a routine pediatrician's appointment for a vaccination. She cried after the shot, but otherwise seemed OK. The doctor told us she would probably have a sore leg the next day, but Tylenol would take care of it. Well, the next day, our daughter wouldn't walk on........

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