I'm not sure that is correct. I think 340.5 applies to med mal and may be longer. I believe 340.4 is injury before birth, but not med mal related. Check out this article in Plaintiff magazine http://www.plaintiffmagazine.com/Dec07%20articles/Watkins%20Stevens_Understanding%20the%20statute%20of%20limitations%20for%20a%20medical%20malpractice%20birth%20trauma%20case_Plaintiff%20magazine.pdf

I think we can all agree that they did not have until the year 2023 to file suit. I would always err on using the earliest potential Statute of Limitations. Anything less is very risky, particularly in birth injury cases. Setting that aside, CCP 340.5 does, in fact, give until 3 years after the injury, or prior to age of 8, whichever is longer, but only applies if the injury occurred before the sixth birthday. It sounds like you cannot wait until the age of 8 however, so, again, I would urge caution and just file suit as soon as possible.