Nope it is not completely true, we know Jupiter is karaka of children when Jup is in capricorn navamsa it is in natural debilitation sign when it enters in aquirius navamsa it releases compounds of energies and gains new nourishing energy .But this concept is only return in books ,it is myth not the truth .

Accordingly for children or to check progeny strength many factor are taken into consideration like D7 and D60 plays important role..