Cutting Teeth--Baby Teeth
One can always talk about averages with babies. In the case of cutting teeth, the average age is 4-7 months, but an early bloomer may have a "pearly-white" as young as 3 months. Some babies are stubborn and don't sprout a first tooth until they're a year old or older. There are even cases of babies who have a tooth at birth. All of these scenarios are within the normal spectrum for tooth development.
The beginnings of teeth, the tooth buds, develop in the womb, inside your baby's gums. Some time after a baby is born the teeth begin to cut through, one or a few at a time, over long months. There's a usual order, but many babies don't follow a predictable tooth-cutting schedule. In general, expect to see the bottom two middle teeth, then the top two, sides, and back. They may look crooked when they first come in, but most of the time, they straighten without intervention.
The second sets of molars come in last, both top and bottom and by age 3, your child should have his complete set of 20 baby teeth. These remain until around the age of 6, when your child makes room for his permanent teeth.
Immune System and Baby Teeth
Some doctors say that teething doesn't cause any symptoms, but others, for instance T. Berry Brazelton, say that the act of cutting teeth weakens the immune system as a stressor. As a result of this weakening, a baby might end up with a cold or ear infection they may have fought off at a time of peak health. Whether or not they become ill, babies who teethe do seem to exhibit common signs of indisposition, for instance, fussing, biting in anger, refusing to eat, sleep disturbances, swollen gums that ache, and excessive drooling that may lead to a facial rash.
Low Fever and Baby Teething
Some parents will blame every medical condition, be it runny stools or noses, on teething. One pediatrician, writer William Sears, author of The Baby Book, thinks that teething can cause diarrhea and diaper rash. Sears says that the excess saliva due to teething ends up in the baby's gut and loosens his stools. Sears also believes that the soreness of the gums due to teething, like any other inflammation, can cause a low fever of less than 101 Fahrenheit.
Call your doctor if your baby has a fever or signs of other medical conditions, for instance an ear infection. Loose stools are going to clear up on their own—no need to call the doctor, as long as it's not pouring out. This will clear up without a physician's help as the teeth emerge.