You can remain physically fit with a baby: What supplies to pack and how to carry an infant along on your hiking trip.
Only Hike In Good Weather
While we didn't hesitate to hike in the rain, or in the cold, when it was just us, it's not work the extra hassle to hike in inclement weather with a baby. Babies have a more difficult time regulating body heat than do adults, and they also do not listen to reason. No matter how much you try, sometimes a baby will persist in hanging a foot, hand, or even head outside of the umbrella or poncho to get cold and wet. This makes for an unhappy baby in the long run.
Check Baby Frequently
Stop often to check on the baby. Check the baby's arms and legs to make sure he or she is warm enough but not overheating. Check the baby's diaper to make sure it's dry and clean. Check to make sure the baby is not hungry. Also, plan to stop every so often just to let baby lay (or sit or crawl or stand) along the trail and explore for a bit. Babies usually enjoy gazing at trees, clouds, and other natural sights.
Diaper Changing
Our family has discovered that hiking trails were not designed with parents of infants in mind. Parents must improvise diaper changing stations. Particularly if you are hiking in mountainous areas where there is a steep drop on one side and a steep climb on the other, stop for diaper changes whenever the opportunity presents itself. (This is much like stopping for gas at every opportunity when driving through sparsely populated areas.) Take along a thick, spacious pad or a small blanket to spread on the ground and consider letting baby play naked in the sunshine for a few minutes.
Carrying Baby
Once baby can sit up, you can carry him or her in a backpack carrier such as those made by Kelty. Until that time, however, you have several options. Many parents choose a soft front pack like a Snugli, but soft front packs can be hard on parents' backs if worn over the course of a full day. Perhaps a better option is a wraparound carrier such as a Moby Wrap or Ellaroo Wrap. These wrap carriers hold baby closer and are also adaptable to many different carrying positions, allowing mom or dad to adjust baby over the course of a hike.
Supplies
In addition to your basic hiking supplies such as emergency shelter, food, water, and first aid kit, you need to take along baby's things, as well. Make sure you have packed enough diapers to last the entire hike. Also pack a small blanket which can serve as a changing pad and also a blanket if baby seems cold. It might be wise to take a change of clothes for baby, as well as a hat it case it gets chilly or rainy. Last, you'll want to make sure you have enough food for the baby. If your baby is breastfed, this will be simple, since moms usually take their breasts with them when they go hiking. If your baby is on formula, pack clean bottles and nipples, formula, and enough water for the day. If your baby is old enough for solid foods, you'll of course want to pack that, as well.
