I take a couple tablespoons of Braggs every day. Doctor says it's great and everything i looked up says it's very beneficial during pregnancy. Like pp, it'd be different if it were dairy, an animal product. Just make sure it's Bragg's, i wouldn't trust any ol brand. This is what their website says:
10 - Is Apple Cider Vinegar safe to take during pregnancy?
Bragg Apple Cider Vinegar is safe to take during and after pregnancy. It helps to rid the body of toxins and may even help with any complications that may arise or have arisen with the pregnancy. It supports regularity and promotes digestion.