Nettle leaves are are a rich source of iron, calcium and folic acid - all essential nutrients during pregnancy. Nettle strengthens the kidneys and adrenals, while relieving fluid retention. Nettle also supports the vascular system. It can prevent varicose veins and hemorrhoids during pregnancy. 
 
It is safe to drink throughout the entire pregnancy. I like to blend in a tea bag of Nettle to a cup of my ever-changing range of herbal teas.