Yes you can!  You can upgrade to this option from any other membership types and if you have recently paid, you will receive a pro-rata discount on your Platinum Challenge membership.  The discount will be calculated based on the number of full months you have remaining on your initial membership.  The discount will be applied automatically as long as you are logged in when you make the purchase.

Login to your account on the Healthy Mummy website, and click on My Offers to upgrade to Platinum today.