Apparently it is high in vitamin A, which combined with vitamin D is wonderful for mama and her growing baby. It's a densely nutritious gift to mama and baby.
The concern that liver has too much vitamin A is addressed in The Nourishing Traditions Book of Baby & Child Care. Sally Fallon Morell and Thomas S. Cowan, MD give us a lot to discuss on this any many, many fabulous topics.
Have you read this book? Do you eat liver - any special recipes?
For more info: Check out The Nourishing Traditions Book of Baby & Child Care. I like this balanced review on Informed Mama blog. Here's another. On pregnant mama's eating liver see The Weston A. Price Foundation.