From what I’ve read, ajawin water is often believed to be beneficial in aiding recovery after birth. It seemed to help with relieving back pain, promotes internal body healing, and also help increases milk production for breastfeeding mothers. Though the effectiveness may not have been studied scientifically (or I have not read any studies on this), it is not harmful to the body and hence, I think there is no harm in trying it.
For more information, you can refer to this article:
http://www.theindusparent.com/ajwain-for-the-new-mother