Looking at the code the state number I said is wrong, it's 36 instead of 63.
Looking at the code it is indeed a state.
From 40_OverEvent_Check.rb on 0.5.6.1
Code:
$game_player.actor.add_state(36) #lactation
The number of stacks of lactation and the presence of the mod determine how much Lona's breasts swell every half day.
If you remove the state the lactation stat is gone from the menu screen the next half day from my limited testing.
edit: f95 glitching out and not sending the whole message
edit2:
Of course, if you have the Breast Mod or the Womb seedbed you'll still lactate, but you can remove these in-game anyway. Only pregnancy lactation sticks around and needs to be removed with cheats.
Lactation state increases lactation level every nap, seedbed state increases lactation level every moved step, breast mod does both.
There
is a lactation stat but it doesn't matter for the most part if you remove the states that cause lactation.
The lactation stat still contributes for the melanin nipples and for when your breasts are touched, but doesn't matter otherwise (lactation level is reset on nap if there's no states).