Jaw trembling in a newborn is usually just one of a host of behaviors that result from the baby’s nervous system being immature. Not only will you see her mouth jiggle from time to time, but you’ll probably also notice lots of sneezes, hiccups, and startles in response to stimuli like loud noises or sudden movement. The most dramatic of these behaviors is the Moro reflex, where the baby’s arms both shoot out as if to grab you and hold on tight!
Generally these jittery movements disappear over the first month or so of life, although of course sneezing and hiccups never go away completely. Jitters that seem extreme or that persist later into infancy, however, can indicate problems with the baby’s nervous system. Your baby’s doctor and nurses will assess her repeatedly after birth for signs of excessive jitters, which may result from drug withdrawal, low blood sugar (hypoglycemia), low blood calcium levels (hypocalcemia), or even oxygen deprivation around the time of birth.
Just like older children and adults, newborns are less jittery when they’re relaxed, warm, and well-fed. Keeping your baby in skin-to-skin contact frequently is likely to put her in a very relaxed mood, which will minimize the shakes, probably for both of you! Remember, if you see a type of movement that worries you don’t hesitate to bring it to the doctor’s attention. I can promise, you will not be the first mom to ask about it, or even the first one that day!