OBJECTIVETo investigate the correlation of gestational age and birth weight with 17α-hydroxyprogesterone (17α-OHP) levels, and with results of adrenal hyperplasia newborn screening.

METHODUsing time-resolved fluorescence immunoassay, the authors measured concentrations of heel blood 17α-OHP by newborn dried blood spots on filter paper which included 29 hospitals newborns of Wujiang, Taicang, Zhangjiagang, Kunshan, and Suzhou, where there were 118 050 infants in total who had accurate gestational age and birth weight (62 490 males, 55 560 females). According to the classification by gestational age, there were 4 693 premature infants, 113 300 term infants and 57 overdue infants. According to the classification by birth weight, there were 4 172 infants with weight < 2 500 g, and 113 878 infants weight ≥ 2 500 g. And, in all premature infants, gestational age of 189 infants was < 32 weeks, 2 277 infants less than 36 weeks but ≥ 32 weeks, and 2 227 infants less than 37 weeks but not less than 36 weeks. Neonatal heel blood concentration of 17α-OHP was measured by dissociation enhanced lanthanide fluorescence immunoassay (DELFIA), and the correlation between 17α-OHP and gestational age or birth weight was retrospectively analyzed by using Spearman test.

RESULTThe distribution of 17α-OHP levels was skew. The 17α-OHP levels decreased significantly from very preterm births, moderately preterm, later period preterm to term infants [19.21 (8.07, 24.00), 12.35 (6.81, 18.00), 8.58 (5.66, 13.80), 5.60 (3.57, 8.51) , 3.34 (2.58, 5.23) nmol/L; 479.42, 62.25, 36.24, 23.30, 13.73 nmol/L;P all = 0.000]. The 17α-OHP levels decreases from very low birth weight (VLBW), extremely low birth weight (ELBW), low birth weight (LBW), normal birth weight to macrosomia [5.24 (3.24, 8.96) , 11.30 (6.84, 22.95) , 8.50 (5.28, 14.90) , 5.66 (3.61, 8.62) , 5.38 (3.40, 8.11) nmol/L; 485.26, 125.18, 39.50, 23.80, 22.15 nmol/L; P = 0.000 for all comparison]. Neonatal 17α-OHP levels and gestational age, body weight was significantly negatively correlated respectively -16.40 and -10.10 (P both = 0.000) by using Spearman test. Neonatal 17α-OHP levels and gestational age, body weight were binomially distributed, and the formulae were y = 0.105 5x²-2.457 6x + 17.689, R² = 0.980 3 and y = 0.411x²-3.988x+14.75, R² = 0.983. Little preterm infants, preterm infants and term infants in low birth weight infants 17α-OHP levels were significantly higher than non-low birth weight infants [11.20 (6.01, 18.90) vs 9.05 (5.85, 14.90) nmol/L, 9.76 (4.32, 10.35) vs 5.59 (3.56, 8.48) nmol/L, P all = 0.000].

CONCLUSIONNeonatal 17α-OHP levels and gestational age, body weight was significantly negatively correlated; in order to improve the accuracy and sensitivity, cut-off value of neonatal 17α-OHP should be adjusted according to gestational age and weight.