| Objective: In recent years, with the cesarean section rate and the incidence and survival rate of preterm infants increasing, it has become important to understand the fetal lung maturity and predict accurately the fetal lung maturity of the fetus before delivery. The content of pulmonary surfactant is closely related to the fetal lung maturity. Always, what played an important role are lecithin, sphingomyelin and phosphatidylgycerol in pulmonary surfactant. So people often use foam test, lecithin to sphingomyelin ratio(L/S), the content of phosphatidylgycerol, lamellar body count(LB) and pulmonary surfactant to albumin ratio to predict the fetal lung maturity, but the method is complex, high incidence of false-positive and false-negative results, such that clinical judgement is false. Recent investigations indicate that surfactant protein can predict development of respiratory distress syndrome(RDS) and better reflect the lung maturity. Compared with the traditional method, incidence of false-positive and false-negative results is low. In the present study, concentrations of SP-A and SP-B in human amniotic fluid and cord blood were determined, to explore 1 different gestational age, mode of delivery and prenatal intervention effect on SP-A and SP-B; 2 correlation between SP-A and SP-B levels in amniotic fluid and cord blood, to further elucidate the change of SP-A and SP-B levels and evaluate their value and significance in the lung maturity.Method: During June 2014 to December 2014, a total of 105 samples were obtained at the fourth hospital of Hebei Medical University. It was divided into three groups according to gestational age:before gestational age 35 weeks(N=28), gestational age ranged from 35 to 37 weeks(N=32) and after gestational age 37 weeks(N=45). It was divided into cesarean section and spontaneous parturition according to mode of delivery in the same gestational age. Before gestational age 35 weeks, there were 18 samples from cesarean section and 10 samples from spontaneous parturition; Gestational age ranged from 35 to 37 weeks, there were 21 samples from cesarean section and 11 samples from spontaneous parturition; After gestational age 37 weeks, there were 23 samples from cesarean section and 22 samples from spontaneous parturition. The samples before gestational age 37 weeks were divided into three groups according to the dose of antenatal dexamethasone. Group I: not given dexamethasone(N=21); Group II: the dose of dexamethasone was less than 20 mg(N=16); Group III: the dose of dexamethasone was greater than or equal to 20 mg(N=23). The cord blood was obtained at birth, amniotic fluid was obtained in cesarean section or delivery. The concentrations of SP-A and SP-B in amniotic fluid and cord blood were determined by enzyme-linked immunosorbent assay(ELISA).Result:1 The SP-A and SP-B levels in amniotic fluid in different gestational ageBefore gestational age 35 weeks, the mean amniotic fluid concentrations of SP-A and SP-B were 130.209 and 25.595 pg/ml, respectively. Gestational age ranged from 35 to 37 weeks, the mean amniotic fluid concentrations of SP-A and SP-B were 163.888 and 29.113pg/ml, respectively. After gestational age 37 weeks, the mean amniotic fluid concentrations of SP-A and SP-B were 174.358 and 32.240 pg/ml, respectively. There were obvious difference in different gestational age by one way ANOVA(P<0.05). There were both obvious difference between gestational age less than 35 weeks, gestational age ranged from 35 to 37 weeks and after gestational age 37 weeks by SNK method(P<0.05). There were no obvious difference between gestational age less than 35 weeks and gestational age ranged from 35 to 37 weeks by SNK method(P>0.05).2 The SP-A and SP-B levels in cord blood in different gestational ageBefore gestational age 35 weeks, the mean cord blood concentrations of SP-A and SP-B were 116.681 and 26.998 pg/ml, respectively. Gestational age ranged from 35 to 37 weeks, the mean cord blood concentrations of SP-A and SP-B were 123.921 and 31.376 pg/ml, respectively. After gestational age 37 weeks, the mean cord blood concentrations of SP-A and SP-B were 144.547 and 35.209 pg/ml, respectively. There were obvious difference in different gestational age by one way ANOVA(P<0.05). There were both obvious difference between gestational age less than 35 weeks, gestational age ranged from 35 to 37 weeks and after gestational age 37 weeks by SNK method(P<0.05). There were no obvious difference between gestational age less than 35 weeks and gestational age ranged from 35 to 37 weeks by SNK method(P>0.05).3 The SP-A and SP-B levels in amniotic fluid in different mode of deliveryBefore gestational age 35 weeks, the median amniotic fluid concentrations of SP-A and SP-B in cesarean section were 129.092 and 23.860 pg/ml,the median amniotic fluid concentrations of SP-A and SP-B in spontaneous parturition were 134.756 and 24.998 pg/ml, respectively. There were no obvious difference between spontaneous parturition and cesarean section by Mann-Whitney U test(P > 0.05).Gestational age ranged from 35 to 37 weeks, the median amniotic fluid concentrations of SP-A and SP-B in cesarean section were 160.312 and 28.901 pg/ml, the median amniotic fluid concentrations of SP-A and SP-B in spontaneous parturition were 178.234 and 30.461 pg/ml,respectively. There were no obvious difference between spontaneous parturition and cesarean section by Mann-Whitney U test(P > 0.05).After gestational age 37 weeks, the median amniotic fluid concentrations of SP-A and SP-B in cesarean section were 183.201 and 36.901 pg/ml,the median amniotic fluid concentrations of SP-A and SP-B in spontaneous parturition were 172.447 and 24.833 pg/ml,respectively. There were obvious difference between spontaneous parturition and cesarean section by Mann-Whitney U test(P<0.05).4 The SP-A and SP-B levels in cord blood in different mode of deliveryBefore gestational age 35 weeks, the median cord blood concentrations of SP-A and SP-B in cesarean section were 114.254 and 26.346 pg/ml,the median cord blood concentrations of SP-A and SP-B in spontaneous parturition were 115.183 and 28.020 pg/ml, respectively. There were no obvious difference between spontaneous parturition and cesarean section by Mann-Whitney U test(P > 0.05).Gestational age ranged from 35 to 37 weeks, the median cord blood concentrations of SP-A and SP-B in cesarean section were 123.567 and 28.891 pg/ml, the median cord blood concentrations of SP-A and SP-B in spontaneous parturition were 125.075 and 35.623 pg/ml,respectively. There were no obvious difference between spontaneous parturition and cesarean section by Mann-Whitney U test(P > 0.05).After gestational age 37 weeks, the median cord blood concentrations of SP-A and SP-B in cesarean section were 135.331 and 29.231 pg/ml,the median cord blood concentrations of SP-A and SP-B in spontaneous parturition were 159.956 and 40.289 pg/ml,respectively. There were obvious difference between spontaneous parturition and cesarean section by Mann-Whitney U test(P<0.05).5 The level of SP-A and SP-B in amniotic fluid in different dose of dexamethasone intervention groupsGroup I, the mean amniotic fluid concentrations of SP-A and SP-B were 145.792 and 29.832 pg/ml, respectively. Group II, the mean amniotic fluid concentrations of SP-A and SP-B were 160.568 and 26.395 pg/ml, respectively. After gestational age 37 weeks, the mean amniotic fluid concentrations of SP-A and SP-B were 143.559 and 26.312 pg/ml, respectively. There were no obvious difference in different dose of dexamethasone intervention groups by one way ANOVA(P > 0.05).6 The level of SP-A and SP-B in cord blood in different dose of dexamethasone intervention groupsGroup I, the mean cord blood concentrations of SP-A and SP-B were 122.715 and 31.242 pg/ml, respectively. Group II, the mean cord blood concentrations of SP-A and SP-B were 123.777 and 29.193 pg/ml, respectively. After gestational age 37 weeks, the mean cord blood concentrations of SP-A and SP-B were 116.561 and 27.955 pg/ml, respectively. There were no obvious difference in different dose of dexamethasone intervention groups by one way ANOVA(P>0.05).7 Correlation between SP-A and SP-B levels in amniotic fluid and cord bloodThe SP-A levels in amniotic fluid and cord blood had no obvious linear relationship in different gestational age by Spearman,s rank order correlation test, Spearman correlation coefficients was 0.369, 0.290 and 0.257, respectively. The SP-B levels in amniotic fluid and cord blood had no obvious linear relationship in different gestational age by Spearman,s rank order correlation test, Spearman correlation coefficients was 0.275,0.245 and 0.407, respectively.8 Analyzed of influencing factorsBy logistic regression, the level of SP-A in cord blood was influenced by gestational age, mode of delivery, fetal position and birth weight(P < 0.05), the greatest impact of gestational age(β=2.091), birth weight subsequently(β=1.465); the level of SP-B in cord blood was influenced by gestational age, mode of delivery and sex(P<0.05), the biggest influence of mode of delivery(β=1.391), gestational age subsequently(β=1.343);the amniotic fluid concentrations of SP-A and SP-B were both influenced by gestational age and mode of delivery(P < 0.05), the greatest impact of mode of delivery,β was 1.199 and 2.561,respectively;gestational age subsequently,β was 1.135 and 1.334,respectively.Conclusion:1 The level of SP-A and SP-B in amniotic fluid and cord blood increases with advancing gestational age, respectively, the smaller the gestational age, the lower the level.2 The level of SP-A and SP-B in cord blood in spontaneous parturition at term is higher than that cesarean section, but the level of SP-A and SP-B in amniotic fluid in spontaneous parturition at term is lower than that cesarean section, probably due to macrophages and the receptors of SP-A take part in parturition, prompts the level of SP-A and SP-B in cord blood can better reflect the lung maturity and spontaneous parturition is better for the lung maturity of full term infant.3 Dexamethasone can increase the lung maturity and may have dose-dependent biphasic effects on the level of SP-A and SP-B.4 The level of SP-A and SP-B is affected by various factors, gestational age and mode of delivery as the main influencing factors, but mode of delivery have less effect on the lung maturity of preterm infant. |
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