1) The new age is 26.

2) The young are the healthiest and cheapest to cover, on average.

3) In most cases, it's not so much an "added" cost as a "returning" cost. In other words, if the premium was good enough to cover the kid at age 18 - or six kids for that matter since most "family" plans cover all kids no matter how many you have - coverage at 19 is just a continuation. This exposes a weakness in how family plans are organized. How many people with one or two kids wonder about what it costs their insurance company to cover (say, a few years ago) a "Jon & Kate + 8" type of family? The births along are 5-figures each.

4) When I worked at Beth Israel Hospital in Boston, a study found that WAY over half the benefits (payouts) from insurance companies went on behalf of just 2% of their subscribers. That was in the late 80s, early 90s - I wonder what it is today?