The sun's rays cause not only sunburn, but also they increase the risk of developing skin cancer later in life. In fact, a majority of our sun exposure (and skin damage) actually happens by the time our kids finish being teenagers. Why? Because children spend more time outdoors than most adults do, especially in the summer. Needless to say, sun protection beginning as early as infancy, as you suggest, is very important to prevent skin cancer later in life.
Our skin remembers each sunburn and suntan year after year. Before you take your infant outdoors, be sure she is protected. Babies less than six months of age should always be kept out of direct sunlight. Their skin is very delicate and will burn much more easily than older children and adults. Babies with naturally darker skin still need this same protection from the sun.
Families can still be outdoors, but move your baby to the shade under a tree or use a stroller canopy. Watch how the shade shifts over time, too. It is best to keep her body covered with lightweight cotton clothing that's tightly woven to help filter out the sun, reflect heat, and keep your baby cooler. A hat with a brim to cover the face and ears provides additional protection. Sunglasses look cute and protect eyes from the sun.
In general, it's recommended not to use sunscreen in infants under six months, except perhaps on smaller areas of the body like the back of the hands (if adequate shade and clothing are not available). It's also best to keep your baby out of the sun when the rays of the sun are strongest (between 10 a.m. and 4 p.m.).
Remember, too, that most of the rays of the sun come through clouds and can cause sunburn even on cloudy days.