Newborns come home from the hospital and immediately begin confusing parents with some of their behaviors. When an infant stiffens her arms, it does not have to mean anything medically serious, although if the baby displays other troublesome symptoms, the parents should immediately call the doctor and take the baby for medical evaluation.
Colic
If a baby suffers from symptoms of colic, her legs and arms stiffen, her abdomen hardens and she cries nonstop, sometimes for several hours. The parents don't know if they are doing something to cause their baby to respond in this manner. They are not. Approximately one in five babies will stiffen and cry, all as worried parents try to figure out what is wrong, states the HappiestBaby website.
Some colicky babies do have abdominal pain while about 60 percent of the babies who cry inconsolably are just fussy. Only 10 percent of inconsolable "colic" crying stems from true colic, while about 30 percent can be traced to the baby being upset.
Parents of a colicky baby should hold onto the thought that this condition should end by the time the baby reaches her 3-month or 4-month birthday.
Infant Behavior
An infant may resist parental cuddling by stiffening his arms. When a baby wants to be cuddled, he will mold himself to his parents' contours, snuggling his head and torso into his mother or father's chest.
The newborn who resists being held and cuddling is usually in a wakeful state, says the March of Dimes website. He may want to see what is going on around him more than he wants a cuddle from mother or father. Stiffening his arms to prevent cuddling is not an indicator that the baby does not like his parents -- it is simply the baby's preference.
Potential Causes
When an infant is born, her nervous system is still immature. For this reason, she may stiffen her arms for one of several reasons, including illness, normal behavior or because she has been startled by a sudden noise.
If a baby has a seizure condition, she may stiffen her arms while a seizure is ongoing. One such condition is called "infantile spasm," which can include extension and stiffening of her arms, writes the MedicalHomePortal website.
Moro Reflex
If a newborn hears a sudden, loud and unexpected noise, such as a loud hand clap, thunder or a pot falling on the floor, he will "startle" and his body will display a characteristic reflex, called the Moro reflex. When this happens, he flings his arms out, with his palms facing out. Immediately after he startles, he pulls his arms back toward his torso and relaxes. Babies exhibit this reflex until they are 3 to 4 months old, states the MedicalHomePortal website.
