The question should really be is flipped around and asked - is the SAD (Standard American Diet) safe during pregnancy. The foods that have been man made and artificially produced in labs to keep people addicted to food don't even get people thinking.... should I be eating that?
Let's think about what cultures did thousands of years ago and that will give us a better idea. They weren't eating the majority of what we have available today.
There is a study that goes over keto being unhealthy while pregnant and if you look at the study - they were consuming things we would never eat on a clean ketogenic diet including highly inflammatory oils.
There are 4 fat soluble vitamins that are vital to mom and baby during pregnancy. A,E,D and K. These are essential and needed for proper development of a baby. You can get these from animal based items without eating grains or processed carbohydrates.
Per my research in alternative health, I will be following a clean ketogenic diet for any future pregnancies.
Clean Keto vs Dirty Keto. I don't even recommend doing a dirty keto diet during pregnancy. Clean whole foods, the least processed the better.
Here are the doctors who I personally chose to take advice from on the topic with their studies linked.
https://www.youtube.com/watch?v=noJunjkx-A8&t=0s
https://www.youtube.com/watch?v=Kv2RVFxtgFA
https://www.youtube.com/watch?v=26DTNsOMMSA
https://www.youtube.com/watch?v=X8aUKfAFecE
https://www.youtube.com/watch?v=q6xTi8jpTec
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*You should always consult your physician before beginning any exercise or diet program especially during pregnancy.