Narrow based baby carriers or "front packs," such as the popular Baby Bjorn*, are controversial in the baby wearing world. Often referred to by the derogatory term "crotch dangler", this style of carrier is not considered ideal in terms of comfort or support for either the baby or the wearer. Despite their flaws, these carriers are widely available and are often the first carrier a new or expectant parent tries.
While they are not actively harmful when used to carry babies with healthy hips, there is some evidence that this type of carrier can exacerbate hip dysplasia due to the non-supportive narrow "seat" this carrier offers. (More info on baby carriers and hip dysplasia here: http://hipdysplasia.org/developmental-dysplasia-of-the-hip/prevention/baby-carriers-seats-and-other-equipment/) Soft structured carriers like the popular Ergo* offer a wider seat and better weight distribution, but may not be affordable.
Enter the scarf hack! Your Baby Bjorn or other narrow-based carrier can be made more comfortable and supportive for both baby and wearer with the simple of addition of a wide scarf, towel, or similar sized piece of fabric. This helps to achieve the recommended knee-to-knee supported seat with knees higher than bum.
Simply center the scarf, towel, or fabric at your baby's back and bum, spread the botttom "rail" across your baby's bum from knee to knee, spread it up to arm-pit level, then pull the ends around behind you and tie securely. Make sure everything is pulled nice and snug for optimal comfort and support. There you go! Comfortable, secure, ergonomically correct babywearing without having to purchase a different carrier or extra equipment! :)