If an infant was born with hair, it probably has begun to fall out by the fourth month, and will continue to come out for several more months. The hair at birth has little relation to the infant's permanent hair and is not an indication of the lifelong color. Because the permanent hair may be growing in at the same time, hair loss may not be noticeable. In a few infants, teething begins as early as the fourth month.
Teething starts with the lower front incisors.
The erupting teeth cause swelling and irritation of the gum, which can be relieved temporarily by rubbing the gum with a clean finger or ice. Sucking actually adds to the infant's distress because it causes blood to rush to the area, and the swelling increases. If rubbing the gums causes a sudden yowl, the answer is probably yes. Continuing to rub will cause the infant to settle down. Giving a little liquid baby acetaminophen may relieve the pain temporarily.