Your experience and perspective can help you reassure your child that his or her child isn't the only one who's ever been through a difficult phase, and that the phase will eventually end. But your experience and perspective also might make you suspect that a grandchild really does have a problem that needs special attention.
Remember that a first-time parent doesn't have much with which to compare a child's development and behavior. Don't be an alarmist, but do keep your eyes and ears open. A grandparent may be in a good position to note something such as unusually slow development of motor skills or language that could signal an illness or condition. Early intervention can make a big difference.
If repeated observation makes you think there could be a serious problem, raise the issue carefully with your child. You might calmly ask if the parents have discussed the situation with their pediatrician. You could say, without sounding alarmed, that it might be worth bringing up.
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