[Grammar] how to dissect 'more so than'?

[qwweewwee]

Hi,there.
I'm new to this forum. I just stumble upon this forum and find it amazing.
Here I have a qusetion concerning the following sentence.
' A study on couples' retirement transitions found that women who took new jobs after retiring from their primary careers reported high marital satisfaction, more so than those who retired completely.'
Admittedly, the meaning of the sentence above isn't difficult to get, but I'm confused by the highlighted part 'more so than', especially the word "so".What kind of role does "so" play in here?;-) In my hunch, I guess the word ''so'' here should be a pronoun, referring to "reported high marital satisfaction." Am i right?
Hope someone out there can dissolve my confusion.
Your explanations will be well appreciated.

 

[a_vee]

This is ridiculously difficult. I have never even considered looking into this. GOOD LUCK!

So - Definition and More from the Free Merriam-Webster Dictionary

 

[5jj]

The link a-vee provided helps:[FONT=&quot] "SO - such as has been specified or suggested : the same <if you have to file a claim, do so as soon as possible>[...][/FONT][FONT=&quot][/FONT][FONT=&quot][/FONT][FONT=&quot] See so defined for English-language learners »[/FONT][FONT=&quot]— used to refer to something that has just been stated or suggested ▪ “Has she left?” “I believe so.” [=I believe she has left] ▪ If you have not yet returned the form, please do so immediately. [=please return it immediately] ▪
We can crudely rephrase your sentence as : [/FONT]' A study on couples' retirement transitions found that women who took new jobs after retiring from their primary careers reported high marital satisfaction, (in fact) even more of what has been specified [= high marital satisfaction] than those who retired completely.[FONT=&quot]'

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[qwweewwee]

Thanks to you, 5jj. Your answer is good, surely clearing my confusion.