How to calculate the SD of change in mean (Pre Post)?

#1
Hi.

Stats dummie here. Trying to do my first meta-analysis using the difference between Pre and Post values, instead using raw values at post.

For that, I need to know the SD of change in means, which many times are detailed in the articles.

As such, I want to know I can determine SD of change in means, when I have SD at baseline and Post?

Thanks
Jorge