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目的研究早产儿甲状腺功能。方法将青岛大学医学院附属医院2004年10月至2005年10月收治的早产儿60例按胎龄分成两组小胎龄早产儿组(A组,胎龄<34周,n1=30),大胎龄早产儿组(B组,胎龄≥34周,n2=30)。对照组为我院出生的正常足月儿30例,应用放免法对3组新生儿生后第1,7天血清游离三碘甲腺原氨酸(FT3)、游离甲状腺素(FT4)、促甲状腺激素(TSH)水平进行测定。结果A、B组及对照组血清FT3、FT4生后1～7d呈下降趋势;对照组生后第1,7天血清FT3、FT4明显高于A、B组,B组明显高于A组;血清TSH在A、B及对照组生后呈下降过程;生后第1天对照组TSH>A组>B组;生后第7天,血清TSHA组高于B组和对照组,而B组与对照组差异无显著性。结论早产儿生后甲状腺功能有暂时性低下,胎龄越小,功能越低,生后应激反应持续时间越长。     

新生儿血清瘦素、生长激素、胰岛素样生长因子-1、胰岛素样生长因子结合蛋白-3水平与宫内发育的关系

目的 探讨瘦素(leptin)、生长激素(GH)、胰岛素样生长因子-1(IGF-1)、胰岛素样生长因子结合蛋白-3(IGFBP-3)在不同宫内发育状况胎儿中的变化,及对胎儿生长发育调控的作用.方法 2004年1月-2006年6月出生早产小于胎龄儿(A组)30例,早产适于胎龄儿(B组)36例,足月小于胎龄儿(C组)32例,足月适于胎龄儿(D组)37例.生后24 h内抽取患儿静脉血,用放射免疫法(RIA)检测其血清leptin、GH、IGF-1、IGFBP-3水平,组间比较采用及多元回归相关分析.结果 各组新生儿血清leptin、GH、IGF-1、IGFBP-3水平均存在明显差异(Pa<0.05,0.01),各指标基本呈C、A、B、D组次序由低到高,但A组IGF-1与C组差异无统计学意义(P>0.05);在A、B和C组,出生体质量与leptin、IGF-1、IGFBP-3呈正相关(Pa<0.01),而D组出生体质量与IGF-1呈正相关(P<0.01),与其他激素无相关性.结论 leptin、IGF-1、IGFBP-3参与宫内发育迟缓儿和早产儿宫内生长发育的调控.IGF-1在早产适于胎龄儿的宫内生长发育中也起调控作用,而leptin、GH、IGFBP-3均不是足月适于胎龄儿生长发育的主要调节因素.     

早产儿生后早期血清降钙素原生理变化规律的研究

目的探讨生后不同时间和不同胎龄的早产儿血清降钙素原(PCT)生理变化规律。方法无感染新生儿217例,其中足月儿115例,早产儿102例,后者依据胎龄分为3个亚组:30～32周(30例)、33～34周(35例)、35～36周(37例),分别研究其生后0～12 h、13～24 h、25～36 h、37～48 h、49～72 h、73～96 h、97～120 h、121～144 h PCT水平变化规律。结果新生儿生后随着时间推移,PCT逐渐升高,24 h左右达高峰,其后逐渐下降,生后96 h左右降至儿童正常值。早产儿组PCT峰值晚于足月儿组,约在生后36 h出现,此后缓慢下降,96 h左右降至和足月儿数据相当。30～32周早产儿生后PCT数值维持低浓度水平,37～48 h逐渐升高,升高时间晚于33～34周及35～36周早产儿。结论新生儿在生后早期PCT有一个先增高后下降的动态变化过程,其中早产儿分泌高峰要迟于足月儿。32周以前早产儿生后36 h之内PCT水平较低。     

早产儿外周血淋巴细胞亚群分布的研究

目的 探讨早产儿外周血淋巴细胞亚群分布及与胎龄、出生体质量关系.方法 检测生后2 h内胎龄28～34周(A组)、34～37周(B组)早产儿及足月新生儿外周血淋巴细胞亚群CD3+、CD3+CD4+、CD3+CD8+、CD4+/CD8+、CDl9+、CD(16+56)+分布情况.结果 早产儿CD3+CI)4+明显高于足月儿,CD3+CD8+、CD19+、CD(16+56)+均明显低于足月儿,差异有统计学意义(P值分别为0.002,0.002,0.036,0.0001);A组CD3+明显高于B组,CD19+、CD(16+56)+明显低于B组,差异有统计学意义(P值分别为0.015,0.025,0.0006);新生儿CD4+/CD8+与胎龄、出生体质量的相关系数分别为0.45和0.48(P值均＜0.01);CD(16+56)+百分比与胎龄、出生体质量的相关系数分别为0.53和0.58(P值均＜0.01).结论 早产儿淋巴细胞免疫功能低于足月儿;胎龄越小、出生体质量越低,其细胞免疫功能越不成熟;新生儿外周血CD4+/CD8+、CD(16+56)+百分比与胎龄、出生体质量有一定的相关性.     

早期药物干预对围生期重度窒息新生儿脑损伤程度的影响

目的：探讨纳洛酮、肝素和复方丹参注射液等联合早期干预对围生期重度窒息新生儿脑损伤程度的影响。方法：180例重度窒息复苏后的新生儿随机分为4组：常规治疗组(A组)45例,即在对症支持处理的基础上使用脑活素和胞二磷胆碱治疗;纳洛酮治疗组(B组)45例,在常规治疗基础上加用纳洛酮;丹参治疗组(C组)45例,在常规治疗基础上加用复方丹参注射液治疗;多药联合治疗组(D组)45例,在常规治疗的基础上尽早(生后6 h内)应用纳洛酮、肝素和复方丹参注射液等联合治疗。观察和比较各组惊厥的发生和病死率,缺氧缺血性脑病(HIE)的临床分度和行为神经评分测定。结果：D组与A组或B,C组比较,前者的惊厥及重度HIE的发生率均明显低于后者(惊厥发生率A,B,C,D组分别为 66.7%,44.4%,53.3%,35.6%,P<0.05;重度HIE发生率A,B,C,D组分别为 53.3%,37.8%,42.2%,26.7%,P<0.05)。生后7～8 d和12～14 d行为神经评分<35分者所占百分比前者亦明显低于后者(生后7～8 d A,B,C,D组分别为 74.3%,50.0%,47.5%,25.6%,P<0.05;生后12～14 d分别为 57.1%,35.0%,32.5%,14.0%,P<0.05),前者的病死率亦较低。结论：对围生期重度窒息的新生儿,在对症支持治疗基础上尽早使用纳洛酮、肝素和复方丹参注射液等,能显著减轻缺氧缺血性脑损伤程度。     

早期胃肠外营养方案对超低出生体重儿电解质的影响

目的探讨早期胃肠外营养方案对超低出生体重儿(ELBWI)出生72h内电解质的影响。方法回顾性分析我院2010—2011年收治的ELBWI的胃肠外营养方案,根据营养方案不同分为早期胃肠外营养组(EPN组)和延迟胃肠外营养组(LPN组),EPN组生后4h内开始予以6.7%小儿氨基酸1.6g/(kg·d),1g/(kg·d)递增,10%葡萄糖酸钙1mmol/100ml,24h内开始予以20%脂肪乳1g/(kg·d),1g/(kg·d)递增;LPN组出生8～24h开始予以6.7%小儿氨基酸0.5g/(kg·d),0.5g/(kg·d)递增,20%脂肪乳0.5g/(kg·d),0.5g/(kg·d)递增,根据血钙水平决定是否补钙。分别于出生后24、48h及72h检测血清钾、钠、游离钙水平,记录每日液体摄入量、尿量及死亡例数等。结果与EPN组相比,LPN组72h内高钾血症、低钙血症发生率均增加(33.3%比3.6%,80.0%比10.7%,P均<0.05),两组胎龄、出生体重、性别、分娩方式、产前激素使用、每日液体入量、血气pH值、血糖等差异均无统计学意义(P>0.05)。结论对ELBWI早期予氨基酸、钙剂以及24h内开始脂肪乳可减少早期电解质紊乱,尤其减少早期非少尿性高钾血症,可以预防致命性高血钾的发生。     

极低出生体重儿血胃泌素和胃动素水平动态研究

目的探讨极低出生体重儿生后1周内血胃泌素(GAS)和胃动素(MOT)水平的动态变化。方法用放射免疫法分别测定20例极低出生体重儿(体重<1500 g)、20例低出生体重儿(体重1500～2500 g)生后12 h、24 h、72 h和7天的血GAS、MOT水平,将15例健康足月儿(体重>2500 g)作对照组。结果 (1)极低出生体重儿组生后12 h、24 h、72 h和7天GAS、MOT水平均明显低于对照组(P<0.01);MOT水平低于低出生体重儿组(P<0.01或P<0.05),GAS水平与低出生体重儿组比较差异无统计学意义(P>0.05)。(2)各组生后72 h内血GAS、MOT水平变化不明显,对照组和低出生体重儿组7天时明显高于72 h(P<0.01),极低出生体重儿组MOT 7天时高于72 h(P<0.05),GAS水平变化差异无统计学意义(P>0.05)。(3)≤33周组各时间点GAS、MOT水平均低于≥37周组(P<0.01)。结论 GAS、MOT水平与新生儿体重、胎龄密切相关。极低出生体重儿生后1周内消化功能低下,GAS、MOT水平先降后升,但变化幅度没有低出生体重儿和足月儿明显,提示功能追赶需要更长时间,临床应选择合适的喂养时机和方式。     

早产及低出生体重儿早期动态血小板计数监测及对比研究

目的　对低出生体重儿及足月新生儿生后一周内的血小板计数进行动态监测及对比研究。方法　将在我院分娩的无合并症的早产儿 10 4例及足月小于胎龄儿 4 2例作为监测对象。同时将足月新生儿 5 9例作为对照组。监测生后 2 4h内及生后 3～ 5d血小板计数。结果　生后 2 4h及 3～ 5d内足月新生儿与早产儿及足月小于胎龄儿血小板计数均值比较无显著性差异 (P值均 >0 0 5 )。仅生后3～ 5d与生后 2 4h内比较血小板计数均值稍有下降 ,但均无显著性差异。 2 4h内早产儿血小板减少的发生率为 3 85 % ,足月儿为 7 2 % ,(P >0 0 5 ) ,无显著性差异。 3～ 5d早产儿血小板减少的发生率为4 0 5 % ,足月儿 5 % (P >0 0 5 )。 2 0 5例被观察者中有 17例血小板低于 10 0× 10 9/L ,发生率 8 3% ,其中仅有 1例为 5 8× 10 9/L ,(0 4 9% ) ,其余均大于 70× 10 9/L。结论　正常低出生体重儿与足月儿比较 ,生后早期血小板计数值动态变化及血小板减少发生率无显著差异 ,而且血小板显著减少的发生率很低 ,因此血小板计数的异常降低可作为新生儿及低出生体重儿危重症评分法的指征之一     

早产儿维生素D两种补充方案的疗效对比：前瞻性随机对照研究

目的 探讨不同维生素D补充方案对出生胎龄 < 34周早产儿生后第28天维生素D营养状况的影响。方法 将59例2018年10月至2019年10月出生胎龄 < 34周的住院早产儿随机分为肌注组（n=30）和口服组（n=29）。肌注组单次肌内注射维生素D₃注射液（10 000 IU/kg）,口服组口服维生素D₃滴剂（900 IU/d）,持续25 d。采集两组患儿生后48 h内（维生素D₃补充前）及第28天静脉血,检测血清25-羟维生素D[25(OH) D]水平。结果 生后48 h内,59例早产儿维生素D缺乏（≤15 ng/mL）率为78%;两组血清25(OH) D水平及维生素D缺乏率比较差异无统计学意义（P > 0.05）。生后第28天,肌注组血清25(OH) D水平显著高于口服组（P < 0.05）,肌注组维生素D缺乏率显著低于口服组（P < 0.05）,且无维生素D过量或中毒病例。结论 单次肌内注射10 000 IU/kg维生素D₃可显著提升出生胎龄 < 34周早产儿生后第28天血清25(OH) D水平,且能安全并有效地降低维生素D缺乏率。     

早产儿维生素D两种补充方案的疗效对比：前瞻性随机对照研究

目的 探讨不同维生素D补充方案对出生胎龄 < 34周早产儿生后第28天维生素D营养状况的影响。方法 将59例2018年10月至2019年10月出生胎龄 < 34周的住院早产儿随机分为肌注组（n=30）和口服组（n=29）。肌注组单次肌内注射维生素D₃注射液（10 000 IU/kg）,口服组口服维生素D₃滴剂（900 IU/d）,持续25 d。采集两组患儿生后48 h内（维生素D₃补充前）及第28天静脉血,检测血清25-羟维生素D[25(OH) D]水平。结果 生后48 h内,59例早产儿维生素D缺乏（≤15 ng/mL）率为78%;两组血清25(OH) D水平及维生素D缺乏率比较差异无统计学意义（P > 0.05）。生后第28天,肌注组血清25(OH) D水平显著高于口服组（P < 0.05）,肌注组维生素D缺乏率显著低于口服组（P < 0.05）,且无维生素D过量或中毒病例。结论 单次肌内注射10 000 IU/kg维生素D₃可显著提升出生胎龄 < 34周早产儿生后第28天血清25(OH) D水平,且能安全并有效地降低维生素D缺乏率。     

Digoxin-like immunoreactive substance in nonoliguric hyperkalemia of the premature infant

Nonoliguric hyperkalemia of premature infants probably results from a transient inhibition of membrane-bound Na+/K+-ATPase during the first 24 h after birth. We hypothesized that the endogenous digitalis-like activity of the serum of premature infants, which inhibits the Na+/K+-ATPase, triggered hyperkalemia. Serum concentrations of potassium ([K+]) and of the digoxin-like immunoreactive substance ([DLIS]) were measured during the first 24 h after birth in 60 infants including 30 infants <30 gestational weeks. Contrary to our hypothesis, there was a negative linear correlation between [DLIS] at birth and [K+] 24 h after birth (r2 = 0.24, p < 0.002). 24 h after birth there was no correlation between [DLIS] and [K+]. Thus, a major role of DLIS in nonoliguric hyperkalemia could not be established.     

Hyperkalemia in very low birth weight infants.

PURPOSE: To assess the frequency and pathogenesis of hyperkalemia in the very low birth weight infant. METHODS: Infants who weighed less than 1000 gm at birth were prospectively entered into the study within 12 hours of birth. Potential risk factors for hyperkalemia were assessed. Body weight, fluid and electrolyte balance, serum levels of sodium and potassium, creatinine clearance, fractional sodium excretion, and urine sodium/potassium ratio were measured every 8 hours for 72 hours. Measurements of plasma renin, serum aldosterone, and plasma atrial natriuretic factor were made at study entry and repeated when hyperkalemia (serum potassium greater than 6.5 mmol/L) occurred or at 72 hours. Infants in whom hyperkalemia developed were compared with those in whom it did not. RESULTS: Thirty-one infants completed the study; hyperkalemia developed in 16 (51.6%). The only difference in the occurrence of perinatal complications was the more frequent occurrence of pH less than 7.20 in infants with subsequent development of hyperkalemia. Creatinine clearance, urine output, and potassium excretion were significantly lower in the hyperkalemia group during the first 24 hours. Serum potassium concentration at 24 hours was inversely related to urine output in the prior 24 hours. Fractional sodium excretion, urine sodium/potassium ratio, and levels of renin, aldosterone, and atrial natriuretic factor did not differ between groups. CONCLUSIONS: Hyperkalemia is a frequent complication in very low birth weight infants. Infants with low urinary flow rates during the first few hours after birth are at greatest risk for the development of hyperkalemia.     

Circulatory failure due to severe cardiac arrhythmia as a result of hyperkalemia in a very low birth weight infant

BACKGROUND: Hyperkalemia is frequently seen during the first days of life in premature infants with a gestational age at birth less than 28 weeks. Normally, these high concentrations of potassium are well tolerated of the premature infants. In a few cases hyperkalemia leads to life-threatening cardiac arrhythmias. CASE REPORT: We report about a 800 grams weighing preterm infant born after 26 + 4 gestational weeks. 24 hours after birth the infant developed 2 : 1 atrioventricular block due to hyperkalemia with a heart rate about 75 bpm. The bradycardia continued about 45 minutes in spite of immediate therapy concomitant by circulatory failure that resulted in an intraventricular hemorrhage of grade III with periventricular intraparenchymal lesions. CONCLUSIONS: The case report demonstrates the variations of the electrocardiogram that can be found in preterm infants with hyperkalemia and their potential risks. Therapy of symptomatic hyperkalemia is not able to interrupt early a life-threatening circulatory failure in any case.     

新生儿早期血清雌二醇水平与肺透明膜病及支气管肺发育不良的相关性初探

目的：检测新生儿早期血清雌二醇（E2）水平的变化规律,探讨其与新生儿肺透明膜病（HMD）、支气管肺发育不良（BPD）发病的相关性。方法：以26周≤胎龄≤32周早产儿59例为研究对象,并设置37周≤胎龄≤42周足月儿61例为对照组,检测生后第1、3、7天的血清雌二醇水平。结果：（1）两组新生儿生后血清E2水平迅速降低,生后第1天、第3天以及第7天间血清E2水平差异有统计学意义。（2）两组新生儿生后第1、3、7天的血清E2水平差异无统计学意义。（3）HMD早产儿血清E2水平与无HMD早产儿比较差异无统计学意义; BPD早产儿生后第3天血清E2水平高于无BPD患儿,而第1、7天的差异无统计学意义。结论：（1）早产儿与足月儿生后血清E2水平在生后7 d内迅速下降;（2）出生后新生儿早期血清E2水平与HMD及BPD无显著相关性,即该激素在新生儿早期不能作为HMD及BPD发病的预测指标。［中国当代儿科杂志,2010,12（11）：864-866］     

Hyperkalemia in very low birthweight infants: incidence and associated factors

The present study evaluated the incidence of hyperkalemia in premature babies born at the Hospital de Clínicas de Porto Alegre (birthweight or=6 mEq/l) and 15.4% with potassium levels subject to cardiac arrhythmia (>or= 6.7 mEq/l). The population was divided into two groups: group KN with potassium < 6 mEq/l (n=16) and group KE with potassium >or= 6 mEq/l (n=10). The hydroelectrolyte management and maintenance of neutral thermal environment was the same for both groups. Neither group received potassium in the first 36 hours of life. The KE group presented higher potassium levels during all the study. The mean birthweights of the groups were similar (KN = 963 gr; KE = 987 gr). The KN group presented a mean gestational age (29.3 weeks x 30.8 weeks) and Apgar Score in the first minute of life (3.18 x 5.7) significantly lower (p = 0.004 and p = 0,015 respectively) than the KE group. There were no significant differences between both groups in relation to the intraventricular hemorrhage, acidosis, hialine membrane disease, insulin level, glycemia, glycemia/insulin index, glomerular filtration rate, diurese, urinary potassium level, fractional sodium excretion, fractional potassium excretion and aldosterone tubular index. The level of aldosterone was significantly higher in the KE group (p = 0.029) within 24 hours of life (212.8 ng/dl x 110.2 ng/dl). It is suggested that none of the studied factors is responsible for the non-oliguric hyperkalemia of the very low birthweight newborn infant, stressing, however, that the serum potassium level must be carefully controlled in those infants.     

围产期早产儿尿蛋白动态变化

目的：研究早产儿肾功能特点及与胎龄、日龄的关系。方法：利用免疫比浊法、速率法及ELISA法,测定28～31周组(Ⅰ组)、32～34周组(Ⅱ组)、35～37周组(Ⅲ组)早产儿生后第1天、第4天、第7天尿微量白蛋白(mAlb)、视黄醇结合蛋白(RBP)、N-乙酰-β-D氨基葡萄糖苷酶(NAG)值。结果：同一胎龄段尿mAlb随着日龄增加有下降趋势,但差异无显著性(P>0.05);同一日龄mAlb随胎龄增加而降低,差异有显著性(P<0.05 或 0.01)。尿RBP,NAG在Ⅰ组和Ⅲ组随日龄增加而增加,在生后第4天形成峰值,而后明显下降,尤以Ⅰ组不同日龄间RBP和NAG差异有显著性(P<0.01 或 0.05)。同一日龄尿RBP,NAG随胎龄增加而明显降低,尤以生后第4天和第7天不同胎龄间RBP和NAG差异有显著性(P<0.05 或 0.01)。结论： 早产儿肾小球、肾小管尚在发育中,受胎龄日龄影响较大。     

Antenatal steroid treatment prevents severe hyperkalemia in very low-birthweight infants*

BACKGROUND: Hyperkalemia is seen quite often in very low-birthweight (VLBW) infants and concentrations sometimes become high enough to cause cardiac arrhythmia. The purpose of the present study was to identify factors that increase serum concentrations of potassium in VLBW infants. METHODS: Retrospective comparative analysis was performed on 140 VLBW infants who had been admitted to the Toho University Perinatal Center between January 1993 and December 1999 and needed mechanical ventilation for respiratory distress. Serum concentrations of potassium at 24 and 48 h of age were compared in two groups of infants, those whose mothers did and did not receive antenatal steroid treatment. Risk factors for severe hyperkalemia were analyzed by multiple linear regression models and Pearson's partial correlation analysis. RESULTS: Antenatal steroid treatment reduced serum potassium concentrations significantly at 24 and 48 h, as well as the incidence of cardiac arrhythmia and necessity for glucose insulin treatment for severe hyperkalemia. Multiple linear regression showed the serum potassium concentration at 24 h of age was associated with antenatal steroid hormone treatment, 24 h fluid intake volume, serum sodium concentrations at 24 h, gestational weeks and sampling site. Serum concentration of potassium at 48 h of age was associated with blood urea nitrogen, gestational week, serum sodium concentration at 48 h of age and fluid intake between 24 and 48 h of age. Urine output volume and serum creatinine concentrations were not correlated with potassium concentrations at either age. CONCLUSION: Antenatal steroid hormone treatment can reduce early hyperkalemia in VLBW infants and also the incidence of cardiac arrhythmia and the use of glucose insulin treatment.     

Fecal sodium and potassium losses in low brith weight infants

We measured 24-hour fecal losses of sodium (Na) and potassium (K) in immediate post natal period of preterm neonates to determine the role of this route in the electrolyte imbalances seen in such infants. The values from preterm infants were compared to a group of age matched term infants. Eleven studies were done on unfed extremely low birth weight infants (group I, birth weight <1200 gms), seven on fed preterm infants (group II, birth weight 1201–2500 gms) and nine on fed term infants (group III, birth weight 2501–4000 gms). Measured and derived variables compared between the groups were 24 hour fecal volume, total fecal electrolyte contents, Na or K lost per kg of body weight and per gm of stool and Na or K losses as percent of intake. Although 24 hour fecal volume was lowest in group I, none of the variables related to Na differed between groups I and II whereas all of them were significantly lower in group I when compared with group III. Groups II and III differed only in terms of Na loss/gm stool which was lower in the previous group. Conversely K loss/gm of stool was significantly higher in group I when compared with both groups II and III and the only variable that differed between groups II and III was a higher fecal K content as fraction of intake. Fecal K/Na ratio was highest in group I, and decreased progressively with advancing gestational age, whereas creatinine clearance was lowest in group I and increased along with gestational age. Serum electrolyte levels were normal, although serum Na concentration was lowest in group I and serum K concentration highest in group II. We conclude that very low birth weight infants have relatively higher fecal K concentrations in the first week of extrauterine life, and speculate that this might have physiological significance as these infants are prone to hyperkalemia during this period.     

脂联素水平在早产儿宫外生长的变化及意义

目的探讨血清脂联素水平在早产儿宫外生长中的变化及意义。方法测定74例早产适于胎龄儿出生24h内和治愈期血清脂联素与胰岛素样生长因子Ⅰ水平。同时监测早产儿体重、记录其营养摄入和并发症；分析血清脂联素水平变化及与早产儿体重的关系，分析影响早产儿宫外生长的临床因素；进行血清脂联素与胰岛素样生长因子Ⅰ水平相关性分析。结果治愈期血清脂联素水平较出生24h内明显上升（P〈0．001）；出生体质量、治愈期体质量分别对24h内和治愈期血清脂联素水平的影响有统计学意义（P〈0．01）。治愈期出现生长迟缓（治愈期体质量小于纠正胎龄平均体质量2个标准差）的早产儿出生胎龄和出生体质量以及出生24h内和治愈期血清脂联素水平均较非生长迟缓早产儿低（P〈0．05）。影响早产儿体质量标准差评分增长的因素有营养摄入、感染性疾病、机械通气〉7d、窒息缺氧（P〈0．05）。出生24h内和治愈期血清脂联素水平与胰岛素样生长因子Ⅰ水平正相关（P〈0．05）。结论早产儿体质量对血清脂联素水平有正性影响，生长迟缓早产儿血清脂联素水平低下。有效的营养和防治并发症，对防止早产儿宫外生长迟缓的发生有重要意义。