My amateur research: correlation between maternal weight gain & baby birth weight

Because I am interested in this stuff, and am a bit of a geek/analyst at heart I wanted to check something.

I recently read an article or 2 claiming that the weight of the baby at birth is directly linked to the weight gain of the mom in pregnancy. It sounds obvious and using JUST me as a sample it would seem to correlate neatly, however my knowledge and experience lead me to suspect it is not as simple or linear as that and so I did my own research on

a local baby related forum I participate in

 to confirm or deny this theory...

So while I do not deny the experts that excessive weight gain is generally bad (and can lead to complications for moms and babies), I don't believe it cannot be looked at in complete isolation and without looking at pre-pregnancy weight, general health and lifestyle (diet and how active the woman is), as well as whether she has issues like gestational diabetes etc TOO.

So here was my enquiry and findings based on responses about 40 pregnancies by regular healthy intelligent South Africa women who all had good maternal care and gained between 6-34 kgs in their pregnancies.

I am doing some amateur research (for myself). I am not convinced it correlates but I want to see, so:
- Of those that put on over 15kgs in pregnancy, did you also have large babies?
- And conversely/the corollary those that have 4+kgs babies did you all put on over 15kgs?
I am not convinced there is a direct link, but I wanted to check the evidence...


UPDATE:

Thanks for the responses guys I have recorded and tabulated the responses and created a graph.

While the graph tracks ascending maternal pregnancy weight gain the baby's weight stays on average exactly the same. Hence my conclusion is there is indeed no obviously direct linear weight gain vs. baby weight link as per my suspicions! 

My graph below: