DB's do not lose essence when they have kids. Exaltation is an imperishable black box miracle of the gods, especially DB Exaltation which is designed to be able to create more Exaltations than it previously had. also the way its worded would suggest that ALL parents lose essence when they have kids which is dumb. Why would an E5 solar suddenly go down to Essence 2 just because they had three kids or something? Especially if they're like a sexy Genghis Khan going around getting it on with the ladies everywhere in a consensual manner because they're just that attractive, so if that rule was true it completely invalidates "sexy wandering hero/warlord" type of Exalt who leaves behind children everywhere they go. Especially since DB's are the one with incentive to do that sort of thing because of the nature of their Exaltation. Exalted is not about enforcing your character to be careful about having sexy times lest with people lest you get weaker through mechanics.

in short, the rule doesn't exist, and its dumb. I can get in contact with the rest of the Exalted community to ask to make sure but their response will in all probability be that the rule is dumb as well.