You can no longer bloodline more than 1 child per year above 18 of your
age. This means you can still have a pretty large family, and more the
older you get, but not ludicrous numbers of children at a young age.
Even visits to Dr. Kortoxian's special fertility clinic won't help you.

This limit applies to your TOTAL children, not children per year. So it
does NOT mean you can only bloodline 1 child this year, then 1 child the
next, etc (unless you're right at your limit). It also doesn't mean you
can only have 1 child who was born in X year, etc. It only means if, for
example, you are 40 years old and have 0 children, you can bloodline up
to 22 children and no more. This goes for mamas AND papas.

Penned by my hand on the 20th of Scarlatan, in the year 421 AF.