Gestational age correlates with skin reflectance in newborn infants of 24-42 weeks gestation

Accurate gestational age determination is limited in very low birthweight infants using neurological and physical assessments. As one of the markers of intrauterine development, skin maturation is assessed qualitatively by pediatricians. Based on this observation, we hypothesize that skin reflec-tance relates directly to gestational age. Light was delivered and collected from the skin through a topically placed optical patch. Reflected light was detected by the spectrophotometer and corrected by an adjacent laptop computer to yield the true total diffuse reflectance as a function of wavelength between 380-820 nm. The calculated reflectance at 837 nm (R₈₃₇) where it is independent of melanin, was determined by extrapolation from the reflectance at 650 and 750 nm. Sixty-four neonates of different races with gestational ages of 24-42 weeks were studied at 2-151 h of age. R₈₃₇ was related exponentially to gestational age (GA) by the equation R₈₃₇ = Rmax 1-exp[-(GA - G₀)/_ԏ], where R_max is the maximal value of R₈₃₇, G₀ is an apparent delay time before dermal scattering increases rapidly, and ԏ a time constant, r = 0.88, p< 0.001. In summary, the extrapolated skin reflectance offers a quantitative and objective assessment of gestational age which is independent of melanin and sex.