Dr. Greene's Answer
Even though you are seeing her teeth for the first time, they have been growing quietly in her gums for some time. The tooth buds that will become the middle 4 teeth on the top usually start to harden during the 3rd or 4th month of pregnancy, but aren’t complete until the baby has been born and is about 4 or 5 months old.
From the beginning they are slowly moving toward the surface, a journey that continues for 3 months or so after these teeth are complete.
Some kids have discoloration of teeth because some pigment is mixed in as a tooth is forming (kinda like a fresco painting, where paint is mixed in wet plaster on a wall).
The antibiotic tetracycline is a classic example of this, but it can also happen with too much fluoride or with conditions like porphyria or even sometimes newborn jaundice.
Sometimes spots on the tooth appear where there is too little calcium or where there is too little enamel on the surface. The teeth may stain or decay easily.
This might happen from a problem at just the wrong moment of tooth development. Perhaps this could be an illness, or premature birth, or difficult birth, malnutrition, kidney failure, or trauma to the tooth.
For some kids with tooth discoloration the cause is hereditary, such as in amelogenesis imperfecta, where the enamel doesn’t form normally, especially in the baby teeth.
Sometimes it’s even the sign of an underlying illness elsewhere in the body.
The bottom line is that it’s time for a trip to the dentist. There are lots of possible causes and possible solutions.
I recommend that babies first see a dentist whenever questions or concerns arise about the teeth as they are coming in — or when they are 2 (or before) if there are no concerns at all about the teeth.