This was a book I found through Kindle Unlimited and I can't find any information about the author and their qualifications.

The book is badly formatted. There are sections that just repeat what earlier sections say. This should have been tightened up into a smaller pamphlet style book. 

It relies on stock photos which means most of the exercises aren't visually shown. The written instructions are not good enough to be used alone, there needs to be a visual element. 

The content is shallow. I don't know who the audience for this is because if it's aimed at pregnant individuals there isn't enough information or guidance. What little there is, is sometimes not actually accurate.

There were no citations. Don't quote medical journals and not cite it. 

There is a section on flexibility and mobility that doesn't seem to relate to anything. Most of the exercises are contraindicated for pregnant people and it doesn't say this. I think this is a general section but don't put it in a Pilates for pregnancy book.

A hypertonic pelvic floor presents the same way as an ‘weak’ pelvic floor. Kegel style exercises are not always recommended and urinary incontinence is not proof your pelvic floor needs strengthening. 

I know it's free and it's tempting to go for the free/cheap option but don't. There are so many good pre/post natal Pilates books or courses or videos. Go find them.