Pixieset offers you the ability to turn on/off color correction when using Lab Fulfillment. Unless you have calibrated and profiled your monitor for the chosen lab, we highly recommend enabling color correction. WHCC and ProDPI, will correct the entire file and balance for skin tones to match their printers' color profile for an additional $0.75 per print product.
Miller's will color correct your image for no additional cost.
Enabling color correction is an extra step that provides excellent and consistent results, and you may find color correction well worth it.