There's nothing quite like the eruption of your baby's first tooth. It's all the more wondrous when you realize that this pearly white has been lurking beneath the surface of your child's gums since your first trimester. Here's a timeline of how it developed.

In Utero

Tooth buds begin to form under your baby's gums in your seventh week of pregnancy. During the rest of the pregnancy and for several months after birth, the growth of roots pushes the hardening teeth toward the gums' surface.

First Teeth

Teething usually begins at about 6 months, but it's not uncommon for the process to start as early as 3 months or as late as 15 months. The two center bottom teeth (central incisors)are usually the first to pop up, followed by the four center top ones (the central and lateral incisors) and then the bottom lateral incisors. These teeth are relatively thin and sharp; they meet with little resistance from the gums and aren't terribly painful when they come in. 

Molars

The first (front-most) set of molars, one in each quadrant, make their entrance around 13 to 19 months, and the second at about 23 months. Not being very sharp or thin, molars are often the most painful teeth to cut. As they push toward the gums, an intense pressure builds up that can cause an eruption cyst - a bluish, translucent bubble of fluid on top of the emerging molar. When the tooth comes in it pops - which looks worse than it is - and vanishes. Even if your child had only minor problems with the first eight teeth, though, you can expect some teething trouble with these monsters.