This MWSE Lua mod makes the player character's endurance-based health gains apply retroactively, as though endurance was at its current value for every previous level. The health bonus is 10% of endurance and the health increase only occurs upon level up, both unchanged from the original game.
It also immediately adjusts your character's health when first added to a game in progress, so you don't have to wait until level up to get the benefit. This adjustment only happens once per character.
In addition, it detects the state of Morrowind Code Patch's Fortify Max Health option and handles fortify health effects accordingly.

An example:
You create a character with 60 strength and 40 endurance, which gives her 50 health.
At level 2, you raise endurance to 43, and her health increases by 4.3 points to 54.3.
At levels 3 and 4, you don't raise endurance, and her health increases by 4.3 points both times to 62.9.
At level 5, you raise endurance to 45.
Normally, her health increases by 4.5 points to 67.4. The total increase from starting health is 17.4.
With this mod, her health increases by 4.5 points for this level, and the health increase for past levels is recalculated to use the current endurance bonus; they increase from 4.3 to 4.5. The total increase from starting health is 18, and maximum health is now 68.
(The game rounds health to a whole number for display, but uses the actual value behind the scenes.)

This is not compatible with mods which avoid the menu-based level up method.
Requires MGE XE and MWSE 2.1.
Made of bits scavenged from NullCascade's UI Expansion, Merlord's Character Backgrounds, and Mort's Ultimate Leveling Experience.