I have a subscription to the OBGYN coding alert because my employer pays for it (along with Codify). I may not always thoroughly read all articles every month, but I have absolutely used previous articles for confirmation and/or references. One year I did purchase (with my employer paying) the OBGYN Specialty Guide. Honestly, I can't recall the last time I opened that book. To me, the online search and computer availability is much more useful than a paper book (especially with hybrid work). If my employer did not pay, I don't think I would personally pay for either (unless I was my own consulting company or something). Honestly, the information in either is mostly available through other sources, just might take more research to find.
Assuming your physician is an ACOG member, you can create your own free account to access coding articles, as well as submit specific coding questions for unusual or complex situations. I have used them a few times for coding questions in the past when my own research led me to conflicting information, or unofficial advice elsewhere that I did not agree with. I do highly recommend their resources.