Postnatal Temporal,Spatial and Modality Tuning of Nociceptive Cutaneous Flexion Reflexes in Human Infants

Cutaneous flexion reflexes are amongst the first behavioural responses to develop and are essential for the protection and survival of the newborn organism. Despite this, there has been no detailed, quantitative study of their maturation in human neonates. Here we use surface electromyographic (EMG) recording of biceps femoris activity in preterm (<37 weeks gestation, GA) and term (≥37 weeks GA) human infants, less than 14 days old, in response to tactile, punctate and clinically required skin-breaking lance stimulation of the heel. We show that all infants display a robust and long duration flexion reflex (>4 seconds) to a single noxious skin lance which decreases significantly with gestational age. This reflex is not restricted to the stimulated limb: heel lance evokes equal ipsilateral and contralateral reflexes in preterm and term infants. We further show that infant flexion withdrawal reflexes are not always nociceptive specific: in 29% of preterm infants, tactile stimulation evokes EMG activity that is indistinguishable from noxious stimulation. In 40% of term infants, tactile responses are also present but significantly smaller than nociceptive reflexes. Infant flexion reflexes are also evoked by application of calibrated punctate von Frey hairs (vFh), 0.8–17.2 g, to the heel. Von Frey hair thresholds increase significantly with gestational age and the magnitude of vFh evoked reflexes are significantly greater in preterm than term infants. Furthermore flexion reflexes in both groups are sensitized by repeated vFh stimulation. Thus human infant flexion reflexes differ in temporal, modality and spatial characteristics from those in adults. Reflex magnitude and tactile sensitivity decreases and nociceptive specificity and spatial organisation increases with gestational age. Strong, relatively non-specific, reflex sensitivity in early life may be important for driving postnatal activity dependent maturation of targeted spinal cord sensory circuits.     

Hormone synthesis and storage in the thyroid of human preterm and term newborns: effect of thyroxine treatment.

Iodine and thyroglobulin concentrations, as well as iodine, T3, T4 and sialic acid contents of thyroglobulin, were measured in thyroid glands collected postmortem from 42 human premature or term newborns and infants. Three groups were considered: very preterm newborns (24-32 postmenstrual weeks, < 5 days postnatal life), preterm and term newborns (34-41 postmenstrual weeks, < 5 days postnatal life) and infants (born at term, postnatal age 1-8 months). Five very preterm and seven preterm newborns received a daily dose of 10 microg/kg L-T4 for at least 3 days. Thyroid weight and sialic acid content of thyroglobulin progressed with maturation. Intrathyroidal concentrations of iodine and thyroglobulin did not increase significantly before the 42nd week of postmenstrual age. The level of thyroglobulin iodination increased during the postnatal life, except in the very preterm neonates. T4 and T3 content of thyroglobulin was directly proportional to its degree of iodination and positively related to its sialic acid content. L-T4 treatment of preterm newborns increased thyroglobulin iodination and T4-T3 content, without increasing thyroglobulin concentration in the thyroid. It was concluded that the storage of thyroglobulin and iodine in the thyroid develops around term birth. This, associated with the resulting rapid theoretical turnover of the intrathyroidal pool of T4 in Tg, could be an important factor of increased risk of neonatal hypothyroxinemia in the premature infants. The L-T4 treatment of preterm newborns does not accelerate the maturational process of the thyroid gland.     

不同胎龄早产儿早期凝血指标的变化及其临床意义

目的:研究不同胎龄早产儿早期凝血指标的变化及其临床意义。方法:选取2012年1月至2017年7月期间我院出生的新生儿392例为研究对象。根据新生儿胎龄的不同分为早期早产儿组(胎龄27~31周)78例、中期早产儿组(胎龄32~33周)102例、晚期早产儿组(胎龄34~36周)116例以及足月新生儿组(胎龄37~42周)96例。四组新生儿出生后2h内抽取静脉血检测凝血指标,包括凝血酶原时间(PT)、活化部分凝血酶原时间(APTT)、纤维蛋白原(FIB),并应用Pearson相关性分析分析新生儿胎龄与上述各项凝血指标水平的相关性。结果:早期早产儿组、中期早产儿组、晚期早产儿组、足月新生儿组的出生体重以及胎龄呈逐渐上升趋势,不同组别新生儿的出生体重以及胎龄差异均有统计学意义(P0.05)。早期早产儿组、中期早产儿组、晚期早产儿组、足月新生儿组PT、APTT均呈逐渐下降趋势,FIB呈逐渐上升趋势,不同组别新生儿PT、APTT、FIB差异均有统计学意义(P0.05)。Pearson相关性分析显示,新生儿胎龄与PT、APTT呈负相关(r=-0.567、-0.691,P=0.000、0.000),而新生儿胎龄与FIB水平呈正相关(r=0.623,P=0.000)。结论:不同胎龄早产儿早期凝血功能存在异常变化,新生儿胎龄与PT、APTT均呈负相关关系,与FIB呈正相关关系,临床应予以重视,及时检测其凝血指标,必要时应予以干预治疗。     

Parameters of Surface Electromyograms in Full-Term and Preterm Infants in the Neonatal Period: The Possible Contribution of Gravity

The purpose of this study was to compare the postnatal evolution of spectral–amplitude and nonlinear parameters of surface electromyogram (sEMG) in the full-term and preterm infants with regard to their biological and calendar age. In full-term infants, all sEMG parameters (dimension, entropy, mean frequency, and amplitude) are increased by 10–30% two weeks after birth. On the contrary, sEMG parameters in preterm infants were constant for six weeks after birth. This finding indicates that both postnatal and antenatal periods are important for the development of the motor system of infants. Therefore, the adaptation of the motor system to extrauterine conditions consists of two stages. The authors suppose that gravity can be a driving factor of these sEMG metamorphoses.     

胎膜早破早产的临床分析

目的:探讨胎膜早破早产的临床处理方法及其对新生儿的影响.方法:以2009年3月至2012年1月在我院产科住院的妊娠满28～36+6周的205例胎膜早破早产患者为研究对象,针对不同孕周,采用相应的治疗方法,并对其妊娠结局和早产儿的状况进行观察和分析.结果:胎龄28～34+6周的早产儿并发症的发生率和死亡率分别为52.2％和10％,胎龄35～35+6周的早产儿并发症的发生率和死亡率分别为32.3％和4.8％,分别明显高于胎龄＞36周出生的早产儿(1.6％和0),差异具有统计学意义(P＜0.05);但孕周在36周以上出生的新生儿的并发症的发生率和死亡率与足月出生的新生儿相比无明显差异(P＞0.05).结论:胎膜早破早产是新生儿患病和死亡的主要原因,胎龄越小新生儿的患病率和死亡率越高,对于胎膜早破早产的孕妇,应针对不同孕周采用不同的治疗方法,以延长孕周以降低早产儿的患病率和死亡率.     

Plasma selenium in preterm and term infants during the first 12 months of life

The goal of the present study was to prospectively assess the plasma selenium (Se) concentrations of term and preterm infants during the first year of life in relation to gestational age and nutrition.

Blood specimens were collected from orally formula-fed preterm infants (gestational age < 32 weeks, birth weight < 1500 g): 1.) in hospital and 2.) corrected for gestational age parallel to healthy term breast and formula-fed infants at the ages of 1, 4 and 12 months. All infants were fed according to a standardized nutritional concept, solids and follow-up formula were introduced at the age of 4 months.

Plasma selenium in preterm infants in hospital was 11.7 (6.5–20.8) g/l and 11.6 (8.8–16.7) g/l at 4 weeks corrected for gestational age. At the age of 4 months plasma selenium was still significantly lower than in the other groups: Preterm infants: 17.1 (10.4–30.5) g/l; formula-fed term infants: 31.3 (24.3–47.5) g/l; breast-fed term infants: 45.6 (27.1–65.1) g/l). The levels of breast-fed infants were significantly higher than those of both formula-fed groups up until the introduction of solids.

Preterm infants had significantly low plasma selenium levels up until a postnatal age of at least 6 months. The levels were lower than those of term infants fed an identical unsupplemented infant formula during the first 4 months of life. These data support routine monitoring in hospital and selenium supplementation of preterm infants, preferably in hospital before discharge.     

Longer Gestation among Children Born Full Term Influences Cognitive and Motor Development

Children born preterm show persisting impairments in cognitive functioning, school achievement, and brain development. Most research has focused on implications of birth prior to 37 gestational weeks; however, the fetal central nervous system continues to make fundamental changes throughout gestation. Longer gestation is associated with reduced morbidity and mortality even among infants born during the period clinically defined as full term (37–41 gestational weeks). The implications of shortened gestation among term infants for neurodevelopment are poorly understood. The present study prospectively evaluates 232 mothers and their full term infants (50.4% male infants) at three time points across the first postnatal year. We evaluate the association between gestational length and cognitive and motor development. Infants included in the study were full term (born between 37 and 41 weeks gestation). The present study uses the combination of Last Menstrual Period (LMP) and early ultrasound for accurate gestational dating. Hierarchical Linear Regression analyses revealed that longer gestational length is associated with higher scores on the Bayley scales of mental and motor development at 3, 6 and 12 months of age after considering socio-demographic, pregnancy, and infant-level covariates. Findings were identical using revised categories of early, term, and late term proposed by the Working Group for Defining Term Pregnancy. Our findings indicate that longer gestation, even among term infants, benefits both cognitive and motor development.     

Longitudinal assessment of pituitary-thyroid axis and adrenal function in preterm infants raised by 'kangaroo mother care'

OBJECTIVE: To assess whether complete kangaroo mother care (KMC), a skin-to-skin contact intervention, would affect longitudinal/developmental patterns of hormonal change. METHOD: An open randomized controlled trial was conducted in a large tertiary care hospital, comparing KMC and traditional care for newborn infants weighing less than 2,001 g. Eighty-seven healthy preterm (<37 weeks gestational age) infants from this study provided three blood-spot samples on filter paper: at randomization (postnatal age 1-5 days), 2 weeks later, and at calculated term (41 weeks gestational age). They met a number of additional inclusion criteria including discharge from the hospital within the first postnatal week. The levels of 17alpha-hydroxy-progesterone (17-OHP), thyroxine-stimulating hormone (TSH) and thyroxine (T(4)) were assessed by radioimmunoassay. Birth weight (<1,800 or > or =1,800 g) and prenatal maternal corticosteroid treatment were taken into account in the analysis. INTERVENTIONS: Complete KMC includes early discharge, positioning the infant on the parent's chest in an upright position, 24 h/day in skin-to-skin contact, and breast-feeding. In the traditional care group, infants were discharged according to routine hospital practice. RESULTS: Levels of 17-OHP and TSH decreased significantly from eligibility to calculated term while T(4) levels did not change significantly over time. Most importantly, overall, treatment (KMC) did not interact with the pattern of physiological change. CONCLUSIONS: Maturation of the pituitary-thyroid axis and adrenal function is apparently not compromised by KMC, at least in healthy preterm infants.     

Acute Histologic Chorioamnionitis Is a Risk Factor for Adverse Neonatal Outcome in Late Preterm Birth after Preterm Premature Rupture of Membranes

Background

The objective of this study was to determine whether acute histologic chorioamnionitis is associated with adverse neonatal outcomes in late preterm infants who were born after preterm PROM.

Methodology/Principal Findings

The relationship between the presence of acute histologic chorioamnionitis and adverse neonatal outcome was examined in patients with preterm PROM who delivered singleton preterm newborns between 34 weeks and 36 6/7 weeks of gestation. Nonparametric statistics were used for data analysis. The frequency of acute histologic chorioamnionitis was 24% in patients with preterm PROM who delivered preterm newborns between 34 weeks and 36 6/7 weeks of gestation. Newborns born to mothers with histologic chorioamnionitis had significantly higher rates of adverse neonatal outcome (74% vs 51%; p<0.005) than those without histologic chorioamnionitis. This relationship remained significant after adjustment for gestational age at preterm PROM, gestational age at delivery, and exposure to antenatal corticosteroids.

Conclusions/Significance

The presence of acute histologic chorioamnionitis is associated with adverse neonatal outcome in late preterm infants born to mothers with preterm PROM.     

Maturation of feedback control of thyrotropin in premature infants

Serum thyrotropin (TSH), free T4 and free T3 concentrations were measured longitudinally in 26 preterm infants for 14 weeks after birth, using highly sensitive immunoradiometric assays. Serum TSH values on days 4-5 were positively correlated with gestational age and birth weight. In the premature infants of 25 weeks mean gestation, the mean TSH concentrations increased from a very low value of 0.84 microU/ml at 5 days to a peak value of 6.1 microU/ml by 5 weeks of age, then slightly decreased and remained stable. Serum free T4 and free T3 concentrations increased in parallel and free T3 level reached the range of term infants by 6 weeks. Serum free T4/TSH and free T3/TSH ratios began to increase at the 6th week of age. The results suggest that: (i) the thyroid hormone feedback control of pituitary TSH release in the extremely premature infants begins to mature after 6 weeks of postnatal age, (ii) the maturation pattern of the hypothalamic-pituitary-thyroid system in premature infants is similar to that of the intrauterine fetus.     

脐血IL-6、IL-8、TNF-a在早产儿脑损伤中的临床意义及预测价值

目的研究脐血白介素-6(IL-6)、白介素-8(IL-8)和肿瘤坏死因子-a(TNF-a)在34周前早产儿脑损伤中的临床意义及预测价值。方法对59例34周前出生早产儿用酶联免疫吸附试验检测脐血IL-6、IL-8、TNF-a;将母亲的胎盘胎膜组织行病理学检查,诊断有无绒毛膜羊膜炎;早产儿出生后72 h内头颅超声检查,诊断有无脑损伤。结果 (1)早产儿脑损伤组脐血IL-6[(7.69±1.69)μg/L]、IL-8[(3.87±0.26)μg/L]及TNF-a[(3.67±1.12)μg/L]明显高于无脑损伤组[分别为(5.78±0.59)μg/L、(1.79±0.66)μg/L、(1.91±0.37)μg/L],2组比较差异有统计学意义(P<0.05);母亲患绒毛膜羊膜炎组脐血IL-6[(6.98±0.17)μg/L]、IL-8[(3.27±0.27)μg/L]和TNF-a[(3.24±1.37)μg/L]明显高于无绒毛膜羊膜炎组[分别为(6.13±0.15)μg/L、(2.04±0.79)μg/L、(2.07±0.54)μg/L],2组比较差异有统计学意义(P<0.05);(2)应用ROC工作曲线进行分析,脐血IL-6≥6.46μg/L、IL-8≥2.0μg/L、TNF-a≥2.42μg/L作为诊断早产儿脑损伤标准时,其灵敏度分别为95.5%、95.5%和100%;特异度分别为94.6%、70.3%和97.3%;(3)母亲有绒毛膜羊膜炎时,早产儿脑损伤发生率明显升高。结论脐血IL-6、IL-8和TNF-a不仅反映母亲的感染情况和早产儿脑损伤,并且对早产儿脑损伤具有一定的预测价值。     

Iodine in contrast agents and skin disinfectants is the major cause for hypothyroidism in premature infants during intensive care

In 51 sick newborns the influence of two different nonionic, iodine-containing contrast agents, Amipaque (group 1) and Omnipaque (group 2) and of long-term treatment with polyvinylpyrrolidone-iodine (PVP-I) (group 3) on thyroid function was studied. In the dose given, freshly dissolved Amipaque releases roughly 100 micrograms 'free' iodide/kg body weight; this release may be even higher in the solubilized agent Omnipaque because of increased breakdown. Urinary iodine excretion was elevated in all groups on day 5 after iodine exposure. In group 1, which included 17 term newborns, the median TSH level was normal after 5 days and 2 weeks, only 1 case of transient hypothyrotropinemia was observed; T4 and T3 median levels were in the lower range of normal. In groups 2 and 3, which included 8 preterm infants of 15 newborns and 9 preterm infants of 19 newborns, respectively, the median TSH values were elevated and T4 and T3 levels were very low. Hypothyroidism was diagnosed in 6 of the 8 preterm and in 1 of the 7 term newborns of group 2. In group 3, 7 of the 9 preterm and 3 of the 10 term newborns reacted with hypothyroidism. Eight preterm and 3 term newborns had to be substituted with thyroxine. The thyroid function of term newborns was less affected by Amipaque or Omnipaque than by PVP-I. The data show that preterm infants are very sensitive to an iodine load.     

Neonatal screening for congenital adrenal hyperplasia in North-Eastern Italy: a report three years into the program

AIMS: To evaluate the incidence of congenital adrenal hyperplasia (CAH) in the Northern Italian population and the efficiency of the North-Eastern Italy screening program. To adjust cut-off levels for 17-hydroxyprogesterone (17-OHP) in relation to gestational age and birth weight, comparing the benefits in terms of reduction of recall rates with the two approaches and ultimately choosing the better of the two. SUBJECTS AND METHODS: Since September 2001, blood samples from neonates born in North-Eastern Italy have been screened with a fluoroimmunoassay method for 17-OHP determination (DELFIA). A preliminary cut-off level of > or = 30 nmol/l was set both for term and preterm newborns. The values of 17-OHP were analysed using statistical methods in relation to gestational age and birth weight in order to modify the cut-off on the basis of our data. RESULTS: After 33 months of screening we screened 128,282 newborns and detected 6 affected babies. During the first 8 months of screening among the recalled babies, 89.6 and 78.1% were preterm and low-birth-weight newborns, respectively, with a recall rate of 2.59% for premature neonates and of 4.94% for babies with birth weights < 2,500 g. We chose a new cut-off value of 50 nmol/l for preterm newborns only and, after 4 months, the recall rate was reduced to 0.83% for these infants and to 1.83% for low-birth-weight infants. CONCLUSION: After 33 months of screening for CAH in North-Eastern Italy, we report an incidence of 1:21,380. In 5 out of 6 affected babies, the diagnosis was established only after a positive screening test, which prevented a severe salt-wasting crisis in these babies. The cut-off level related to gestational age led to a significant reduction in the number of false-positives among preterm babies.We therefore intend to continue with the screening program for CAH in North-Eastern Italy, keeping a gestational-age-related cut-off in the hope that our data may encourage a national screening program for CAH.     

Upper airway muscle activity during nasal occlusion in newborn babies

Submental electromyorgams (SM EMG) were recorded from 20 preterm babies (gestational age 30 +/- 2 wk, postmenstrual age at study 35 +/- 2 wk) (mean +/- SD) and 3 full-term infants (7-14 days old). SM EMG was evaluated during eupnea and brief experimental airway occlusion. Phasic inspiratory SM EMG was rarely seen during eupnea. SM EMG tended to increase on the first occluded effort, although this increase was not statistically significant in most babies. All infants showed progressive breath-by-breath augmentation of phasic SM EMG during occlusions in rapid-eye-movement (REM) as well as quiet (QS) sleep; phasic increases in SM EMG were similar during REM and QS occlusions in the majority (16/22) of babies. Periods of airway closure were detected during 24 occlusions in 5 infants; phasic SM EMG was reduced on these occasions. The results are consistent with the idea that recruitment of upper airway muscles contributes to the stability of the airway of the preterm human.     

Plasma protease inhibitors in premature infants: influence of gestational age, postnatal age, and health status

In newborn infants, the influence of gestational age (GA), postnatal age (PA), and health status on the plasma protease inhibitors alpha 2-macroglobulin (alpha 2-M), alpha 1-antitrypsin (alpha 1-AT), C1 esterase inhibitor (C1E-INH), alpha 2-antiplasmin (alpha 2-AP), and antithrombin III (AT-III) was investigated. Inhibitor levels were measured by radial-immunodiffusion and expressed as a percentage of pooled plasma from adults (mean +/- SEM). In total, 54 premature infants (28-36 weeks gestation) were classified at birth as healthy (N = 22) (IV fluids, antibiotics only) or sick (N = 32) (all other support, but excluding infants with disseminated intravascular coagulation (DIC] and studied on Days 1 and/or 7 of life. Healthy term infants (N = 18) and infants with DIC (N = 10) were studied on Day 1 only. All inhibitors except C1E-INH increased with increasing gestational age (P less than 0.01). In healthy premature infants all inhibitor levels reached the normal adult range by 1 week of age. In contrast, at 1 week of age, sick infants had lower levels of alpha 2-M and alpha 2-AP, and higher levels of alpha 1-AT compared to healthy infants (P less than 0.01). The presence of DIC depressed all of the inhibitors on Day 1 except alpha 1-AT when compared to healthy controls (P less than 0.01). Thus, gestational age, postnatal age, and health status all significantly influenced the levels of these plasma protease inhibitors.     

胎盘组织学绒毛膜羊膜炎与未足月胎膜早破后早产儿脑损伤关系

目的:研究胎盘组织学绒毛膜羊膜炎与未足月胎膜早破后早产儿出现脑损伤的相关性。方法:选取我院妇产科2017年1月至2019年12月收治的因胎膜早破生产的未足月早产儿80例,根据是否存在绒毛膜羊膜炎分为观察组(绒毛膜羊膜炎)和对照组(无绒毛膜羊膜炎),每组40例,患儿于胎龄40 w时行颅脑核磁共振检查(Magnetic Resonance Examination,MRI),对比两组脑室周围白质软化(periventricular leukomalacia,PVL)阳性率,且采用新生儿20项行为神经评分量表(neonatal behavior neurological assessment,NBNA)评价两组患儿神经行为,然后在纠正胎龄3、6个月时对两组患儿进行智能发育指数(mental developmentalindex,MDI)及心理运动发育指数(psychomotor development index,PDI)测定并对比。结果:观察组PVL阳性率为27.5%,高于对照组的10.0%(P<0.05);观察组纠正胎龄40 w NBNA得分为(31.02±3.51)分,对照组为(35.21±4.02)分,差异具有统计学意义(P<0.05);胎龄3个月,MDI得分在观察组与对照组间差异无具有统计学意义(P>0.05),但其PDI得分低于对照组(P<0.05);胎龄6个月,观察组MDI及PDI得分均低于对照组(P<0.05)。结论:绒毛膜羊膜炎与未足月胎膜早破后早产儿的脑部损伤情况具有一定相关性,可以作为预测早产儿脑损伤程度的一项指标。     

Plasma and urine amino acid pattern in preterm infants on enteral nutrition: impact of gestational age

Plasma and urine amino acids were determined by ion-exchange chromatography in 80 healthy preterm infants divided into three groups: (1) 23 0/7–28 0/7, (2) 28 1/7–32 0/7 and (3) 32 1/7–35 0/7 weeks of gestation. Samples were collected from days 5 to 57 of life, when infants were exclusively orally fed. Infants with evidence of underlying diseases were excluded. Concentrations of most plasma amino acids increased with gestational and maturational age; urinary excretion followed an opposite course. Few amino acids depended on postnatal age. Plasma amino acids did not correlate inversely to their counterparts in urine indicating that plasma amino acids do not simply reflect kidney function. Some amino acids in blood and urine were linked to nutrient intake and body weight. Our data clearly indicate the heterogeneity of the preterm cohort; therefore, gestational age-matched reference values have to be used for diagnostic purposes in preterm infants.     

Detection of secretory immunoglobulin A (SIgA) in saliva of ventilated and non-ventilated preterm neonates

The very young preterm neonate has multiple immune deficiencies which may increase his or her vulnerability to infection. Secretory Immunoglobulin A (SIgA) plays an important role in the protection of epithelial surfaces exposed to the external environment; nevertheless controversy exists with regards to the ontogeny of SIgA in newborns and especially the preterm neonate. The objective was to investigate if SIgA could be detected in the saliva of very/extremely low birthweight neonates (V/ELBW). A total of 707 samples which were collected twice daily (morning and afternoon) for three consecutive days were obtained from sixty-eight preterm neonates (mean gestational age 28 weeks; conceptional age ranged from 25-35 weeks). A repeated measures design was used. Total concentration of SIgA was determined from unstimulated saliva by an Enzyme Linked Immunosorbant Assay technique. Results indicated that SIgA was detectable in the early postnatal period in the saliva of both ventilated preterms who were receiving intravenous total parenteral nutrition (TPN) and non-ventilated preterms. A 3-way repeated measures Analysis of Variance (ANOVA) showed no significant effect from 'before' and 'after' samples during a period of spontaneous activity, time and day of sampling. A significant effect of mode of nutrition was found; neonates who were receiving expressed breast milk had significantly higher concentrations of SIgA than those infants receiving TPN (df=3, F=14.27, p<0.0001). These results have implications for the care of the preterm neonate in intensive care.     

Investigation of the intestinal microbiota in preterm infants using different methods

Modifications in microbial colonization of the human gut are believed to affect intestinal homeostasis and increase the risk of gastrointestinal diseases. The present study examined different methods for investigating the dynamic characterization of the intestinal microbiota in preterm infants. Fecal samples were collected weekly from ten preterm infants during their stay in a neonatal intensive care unit. The infants had a mean gestational age of 29 weeks (range: 28–32 weeks) and a mean birth weight of 1233 g (range: 935–1450 g). Bacterial colonization was assessed using conventional culture techniques and molecular biological methods. More specifically, the recently developed denaturing high performance liquid chromatography (dHPLC) technique was compared to established methods such as temporal temperature gradient gel electrophoresis (TTGE) and rRNA gene library sequencing. Our results indicate that the gastrointestinal tract of preterm infants, born at a gestational age of less than 33 weeks, has a low biodiversity of mainly, culturable bacteria. Finally, dHPLC was evaluated in terms of speed, labor and sensitivity for its use as a tool to analyze microbial colonization in preterm infants. We found that this technique provided major improvements over gel-based fingerprinting methods, such as TTGE, that are commonly used for studying microbial ecology. As such, it may become a common analytical tool for this purpose.