Neurological and physical maturation in normal growth singletons from 37 to 41 weeks' gestation

An evaluator blinded to gestational age (GA) assessed a cohort of 397 singl etons born at between 37 and 41 week's gestation, by looking at 11 criteria exploring neurological maturity and 12 criteria exploring physical maturit y. The analysis of correlation coefficients shows various degrees of associ ation between GA and each of the criteria examined. A highly significant co rrelation (p < 0.001) was found for 4 neurological criteria defining passiv e tone in limbs and sucking reflex. The activity of flexor muscles of the n eck and crossed extension reflex were also associated with maturity but wea kly (p < 0.01). A highly significant correlation (p < 0.001) was found for 8 of the physical criteria, skin colour and texture, lanugo, ear firmness, genitalia, breast size, nipple formation and plantar skin creases. Oedema, skull firmness and ear form were also associated but weakly. With multivari ate analysis combining the neurological and physical criteria, predictive v alues ranked in the following order: 1) plantar skin, 2) breast size, 3) su cking reflex, 4) scarf sign, 5) skin colour, 6) genitalia, 7) popliteal ang le, 8) return to flexion of forearms, 9) dorsiflexion angle. In conclusion, a score based on physical and neurological criteria is associated with dur ation of pregnancy (r(2) = 0.32) between 37 and 41 weeks' gestation. Such a n instrument allows us to study fetal maturity as a variable independent of GA, and therefore makes it possible to identify various influences that ma y modify maturational rate during the last weeks of pregnancy. (C) 1999 Els evier Science Ireland Ltd. All rights reserved.