Gray card vs. baby skin

Gray cards are to provide a standard reference for exposure in photography. The color, 18% gray, is an empirical result. The card comes with two sides, one side is 18% gray for exposure measurement, the other side is white for white balance calibration.

This is a sample of 18% gray color.You can see how much it could differ from a baby skin. The picture could be under exposed if I only do a point and shot on my daughter's face. I believe most parents have no time to cut in a gray card to calibrate the shooting-star moment. I usually need to add +1/3~+2/3 level up or just do an exposure lock on the nearby gray area to get better exposure.
1) Point and shoot result:
2) +1/2 Exposure: