Growth in extremely low birth weight infants up to three years

OBJECTIVE: To evaluate postnatal growth of extremely low birth weight infants (ELBW, <1,000 g) until 36 months of corrected age (CA), and to relate growth outcome to anthropometric parameters at birth, sex, fetal growth status (small or appropriate for gestational age--SGA/AGA), period of admission and major perinatal events. STUDY DESIGN/METHOD: Weight (Wt), height (Ht) and head circumference (HC) were assessed in 159 ELBW infants. Data were standardized with Z-scores following Usher and McLean and Sempe growth curves. Uni- and multivariate statistical analysis were performed. RESULTS: The mean birth weight was 851.2+/-116.5 g. Z-scores decreased from birth to term, at a deeper rate for AGA than for SGA infants (p<0.005 for Ht, Wt, and HC). Between term and 36 months, growth was better in SGA compared with AGA infants (p=0.003 for Ht). Multivariate analysis showed that anthropometric parameters at birth were positive determinants for Wt, Ht and HC at term, and also for Wt and Ht at 36 months CA (Z-scores). Oxygen therapy after 36 weeks of post-conceptional age was a negative determinant influencing growth at 36 months CA (Z-scores). CONCLUSIONS: Significant catch-up growth took place between birth and 36 months, which was greater for SGA than for AGA infants. Anthropometric parameters at birth and oxygen therapy at 36 weeks post-conceptional age are the main predictive factors for growth at 36 months CA.     

Anthropometric assessment of nutritional status in newborn infants. Discriminative value of mid arm circumference and of skinfold thickness

74 appropriate-for-gestational age (AGA) and 22 small-for-gestational age (SGA) caucasian infants were studied for anthropometric parameters: mid arm circumference (MAC), triceps and subscapular skinfold thickness (TSKF and SSKF) recorded at 15 and 60 s, chest circumference (cc), head circumference, birth weight and length.MAC is highly correlated with birth weight either in AGA (r = 0.936; P < 0.001) or in SGA infants (r = 0.860; P < 0.001). MAC is also correlated with gestational age in AGA (r = 0.850; P < 0.001) and SGA infants (r = 0.76; P < 0.001). Similar correlations were found between TSKF, SSKF and birth weight or gestational age. Arm muscle and fat areas are also positively correlated with birth weight and gestational age, in AGA and SGA infants.A multiple regression analysis of our data allowed a classification of the best discriminant anthropometric parameters between AGA and SGA infants. MAC, SSKF15, SSKF60 and chest circumference were selected. An equation was established in AGA infants with these four parameters giving a predictive gestational age: gestational age (weeks) = 1.216 MAC (cm)?3.588 SSKF15 (mm)+0.263 CC (cm) + 17.9.The ratio of predicted gestational age to the real gestational age was 1.0 ± 0.044 in AGA versus 0.896 ± 0.034 in SGA infants.Our data suggest that MAC and SSKF provide a simple measure of body composition of neonates and a useful tool for determining the degree of maturity of a newborn independent of birth weight.     

Asymptomatic hyperammonemia in low birthweight infants

At 0-3 days of age the plasma ammonium concentration in full term appropriate for gestational age (AGA) infants was (mean +/- SEM) 27.5 +/- 0.5 micron; a value similar to that reported in adults. Ammonium levels in low birthweight AGA and SGA groups were 47.0 +/- 2.0 micron and 45.1 +/- 3.3 micron respectively; significantly elevated (P less than 0.001) as compared to the full term group. These increased ammonium levels persisted at 3-5 weeks of age. Associated with the hyperammonemia was a significant (P less than 0.01) decrease in plasma alpha-ketoglutarate concentration: 11.8 +/- 1.0 micron, in the low birthweight AGA as compared to 20.7 +/- 0.6 micron in the full term AGA infants. There was an inverse linear correlation between plasma concentrations of ammonium and alpha-ketoglutarate r = -0.86, P less than 0.001. Urinary orotate excretion was significantly elevated (P less than 0.05) in low birthweight AGA infants. There was no difference in the plasma concentrations of glutamine, glutamate, or alanine among the various groups. Hyperammonemia was not associated with neurologic dysfunction.     

Effect of oral lipid administration on glucose homeostasis in small-for-gestational-age infants

The metabolic effect of feeding with 1.3 g/kg bw lipids (67% medium chain triglycerides) was studied in 15 small-for-gestational age (SGA) term infants. It was compared to a control group of 7 SGA term infants, to 7 term infants with an appropriate birth weight (AGA) and to 7 AGA preterm infants. Plasma glucose concentration rose from (M +/- SE) 3.6 +/- 0.2 to 4.4 +/- 0.3 mmol/l at 30 min in SGA term infants (p less than 0.01). A similar increase was observed in AGA term and preterm infants. The lipid load produced no change in plasma glucagon concentration but a significant increase in insulin/glucagon molar ratio was observed in AGA term infants only. In term SGA infants, the disappearance rate of glucose in plasma after the lipid load was similar to the control: 1.24% per min. The evolution of blood pyruvate and lactate concentration was not modified by the lipid load. Despite lower concentrations of free fatty acids and ketone bodies (KB) in SGA infants than in AGA term infants, the lipid load induced a 120% increase of ketone bodies in SGA infants and a 40% increase only in AGA infants. These data show that these lipids produce a hyperglycemic response in SGA infants as in AGA infants without any change of the disappearance rate of glucose. They suggest that these lipids can stimulate gluconeogenesis and ketogenesis in SGA infants.     

The influence of gestational age, size for dates, and prenatal steroids on cord transferrin levels in newborn infants

Serum transferrin levels assess protein status in older children and adults. To generate standards for its use in newborn infants, we measured umbilical cord serum transferrin levels in 161 appropriate (AGA), 25 large (LGA) and 16 small (SGA) for gestational age infants between 25 and 43 weeks' gestation. We also assessed the effects of intrauterine growth, exposure to prenatal steroids, and presence of pulmonary maturity on neonatal transferrin levels. Cord transferrin levels in AGA infants were significantly correlated with increasing gestational age (r = 0.60; p less than 0.001). Infants born before 37 weeks' gestation had significantly lower transferrin levels, when compared with those born at term (p less than 0.001). LGA infants had significantly higher levels than age-matched AGA infants (253 +/- 75 vs. 214 +/- 53 mg/dl; p less than 0.025). Despite significantly lower mean birth weights (p less than 0.001), SGA infants also had significantly higher levels than gestational age-matched AGA controls (227 +/- 63 vs. 167 +/- 40 mg/dl; p less than 0.005). For infants less than 35 weeks' gestation, neither the 20 preterm infants with exposure to prenatal steroids (maternal betamethasone), nor the 26 infants with pulmonary maturity had significantly elevated transferrin levels, when compared with gestational age-matched control infants. Newborn transferrin levels correlate well with gestational age and are significantly affected by size for dates, but not by a brief course of prenatal steroids or by pulmonary maturity.     

Catch-up growth of head circumference of very low birth weight,small for gestational age preterm infants and mental development to adulthood

OBJECTIVE: To examine the influence of postnatal energy quotient (EQ, energy intake/kg body weight per day) on head circumference (HC) growth and mental development of very low birth weight (VLBW), small for gestational age (SGA, <10th percentile) preterm infants. STUDY DESIGN: SGA VLBW preterm infants (n = 46) with primarily symmetric intrauterine growth restriction were compared with 62 appropriate for gestational age (AGA) VLBW preterm infants and 73 term infants from the Bonn Longitudinal study. RESULTS: Twenty-seven of 46 (59%) of the SGA preterm infants showed complete HC catch-up growth by the age of 12 months, but mostly before 6 months after term (HC catch-up group). These infants had significantly higher mean EQs from day 2 to 10 than the group of 19 infants without HC catch-up (EQ, 95 vs 78). Mean EQs correlated significantly with developmental and intelligence quotients (DQ/IQ) from 18 months to 6 years. As adults, the HC of the HC catch-up group was not significantly different from that of the AGA preterm infants, the term infants, and their parents. The group without HC catch-up had smaller HC as adults. CONCLUSIONS: Our data suggest that early postnatal high-energy nutrient intake for SGA preterm infants is needed to promote HC catch-up growth and to prevent negative consequences of undernutrition.     

小于胎龄儿青春前期女孩硫化脱氢表雄酮和胰岛素水平的研究

目的探讨小于胎龄儿(SGA)青春前期女孩肾上腺机能初现及是否具有肾上腺机能早现、高肾上腺雄激素血症、高胰岛素血症和胰岛素抵抗现象。方法以符合纳入标准的SGA 39例为研究对象,年龄(7.4±1.7)岁,42例适于胎龄儿(AGA)为对照组,年龄(7.4±1.7)岁。在隔夜空腹12 h后,行身体检查,并抽血检测空腹血糖、胰岛素、硫化脱氢表雄酮(DHEAS)、皮质醇和雌二醇。胰岛素敏感性用空腹血糖与胰岛素乘积的倒数再取自然对数来评价。结果两组中未发现肾上腺机能早现的临床表现,两组间孕母孕龄、年龄、体重指数、空腹血糖、皮质醇、雌二醇和胰岛素敏感性指数差异无统计学意义。SGA组出生体重、研究时的身高和体重均低于AGA组,SGA血清胰岛素和DHEAS水平均高于AGA组(对数转换值:1.076±0.041vs.1.050±0.051,P<0.05;2.637±0.271vs.2.514±0.250,P<0.05)。AGA组DHEAS值在7岁以后出现明显增加,SGA组DHEAS值出现增加的趋势与AGA组比较有所提前。结论AGA女孩肾上腺机能初现的年龄约为7岁,而SGA女孩肾上腺机能初现有始动提前的趋势,青春前期SGA女孩有高肾上腺雄激素血症和胰岛素水平升高的现象,但以胰岛素敏感性指数来评价,尚未发现胰岛素抵抗现象。     

Term infants with fetal growth restriction are not at increased risk for low intelligence scores at age 17 years

OBJECTIVE: To assess the long-term cognitive outcome of small for gestational age (SGA) compared with appropriate for gestational age (AGA) infants. DESIGN: Data from the Jerusalem Perinatal Study was matched with information from the army draft medical board. SGA and severe SGA were defined as birth weight below the 10th and 3rd percentiles for gestational age, respectively. A multiple linear regression analysis was performed to control for clinical, perinatal, and socio-demographic confounding variables. SUBJECTS: A cohort of 13,454 consecutive singleton term infants born between 1974 and 1976. Main outcome measure: IQ at age 17 years. RESULTS: SGA infants had lower adjusted mean +/- SE IQ scores compared with their AGA peers: 102.2 +/- 0.9 versus 105.1 +/- 0.7 (P <.0001) for males and 102.5 +/- 0.9 versus 103.9 +/- 0.7 (P <.015) for females. SGA was not associated with lower academic achievements compared with AGA. CONCLUSION: After controlling for multiple confounders, being born SGA at term is associated with slightly lower intelligence test scores at age 17 years. However, the clinical significance of the small difference is not evident in academic achievements.     

Metabolic consequences of intrauterine growth retardation in very low birthweight infants

By the combination of energy and macronutrient balances, continuous open circuit computerized indirect calorimetry, and anthropometry, we have compared small for gestational age (SGA) and appropriate for gestational age (AGA) very low birthweight infants with respect to metabolizable energy intake (mean +/- SE: 125.9 +/- 2.5 versus 130.4 +/- 3.5 kcal/kg X day), energy expenditure (67.4 +/- 1.3 versus 62.6 +/- 0.9 kcal/kg X day), storage of energy and macronutrients and growth. Fourteen studies in six SGA infants (gestational age, 33.1 +/- 0.3 weeks; birthweight, 1120 +/- 30 g) and 22 studies in 13 AGA infants (gestational age, 29.3 +/- 0.4 weeks; birthweight, 1155 +/- 40 g) were performed. The SGA infants had a lower absorption of fat (68.7 +/- 3.2 versus 79.7 +/- 1.7%) and protein (69.1 +/- 3.2 versus 83.4 +/- 1.5%) and hence increased (P less than 0.001) energy loss in excreta (29.9 +/- 2.8 versus 18.2 +/- 1.5 kcal/kg X day). The significant hypermetabolism of SGA infants by 4.8 kcal/kg X day was associated with an increased fat oxidation. Despite lower energy storage, SGA infants were gaining weight (19.4 +/- 0.9 g/kg X day), length (1.25 +/- 0.14 cm/week), and head circumference (1.16 +/- 0.9 cm/week) at higher rates than the AGA group. The energy storage per g weight gain was lower (P less than 0.001) in the SGA group (3.0 +/- 0.14 versus 4.26 +/- 0.26 kcal) reflecting higher water, lower fat (22.2 +/- 1.8 versus 33.8 +/- 2.5%; P less than 0.001) and lower protein (7.7 +/- 0.5 versus 12.5 +/- 0.8%; P less than 0.001) contents of weight gain in the SGA group.     

Increased energy expenditure and fecal fat excretion do not impair weight gain in small-for-gestational-age preterm infants.

In order to optimize the nutrition of high-risk premature infants beyond the early postnatal period, a more precise knowledge of individual nutritional requirements is needed. We therefore studied the influence of intrauterine growth retardation on energy expenditure and nutrient utilization determined by indirect calorimetry and fecal fat excretion (steatocrit) in nineteen premature infants who were appropriate-for-gestational-age (AGA; mean gestational age 29.9+/-0.3 weeks, mean birth weight 1.30+/-0.05 kg) and thirteen small-for-gestational-age (SGA) premature infants [mean gestational age 32.4+/-0.5 weeks, mean birth weight 1.024+/-0.07 kg (i.e., below the 10th percentile)] during the first and second month of life. All infants were clinically stable during the study period. In nine SGA infants we observed a significantly higher steatocrit compared to twelve AGA infants (29+/-1 vs. 17+/-1% p = 0.0001). SGA infants (n = 12) also showed a slightly (albeit statistically not significantly) higher energy expenditure than AGA infants (n = 15) (58.7+/-1.9 vs. 53.6+/-1.5 kcal/kg per day, p = 0.054). Despite the increased fat excretion and higher energy expenditure, SGA infants gained weight more rapidly during the study period than AGA infants (20+/-1 vs. 17+/-1 g/kg per day, p = 0.026). We conclude that influences of intrauterine growth retardation on energy expenditure and nutrient utilization persist during the first weeks of extrauterine life. However, these metabolic changes do not impair the capability of SGA infants for extrauterine catch-up growth if adequate nutrition is provided.     

Growth and mineral metabolism in very low birth weight infants. I. Comparison of the effects of two modes of NaHCO3 treatment of late metabolic acidosis.

Twenty-six infants weighing less than 1,300 g at birth were divided into pairs according to birth weight (900-1,100 and 1,101-1,300 g) and gestational age ("appropriate" (AGA) = mean 31 weeks; and "small" (SGA) = mean 34 weeks). One member of the pairs was then allocated randomly to one of two treatment regimens with oral sodium bicarbonate. Group A was treated whenever base excess was greater than -8mEq/liter as detected on twice weekly testing and/or when suspected to be acidotic from failure to gain weight. In group B, base excess was maintained within 1 SD of normal (-3.2 +/- 1.7 mEq/liter). The infants received Enfalac 200 ml/kg/24 hr, at 67 cal/100 ml, with vitamin D 400 IU/24 hr added from age 2 weeks. The following measurements were made: daily weight, weekly length, skinfold thickness, head circumference, twice weekly blood pH, PaCO2, base excess, and weekly plasma total calcium, ionic calcium, total magnesium, inorganic phosphorus, and total protein. There were six pairs of each of AGA and SGA infants and two unpaired group A infants. Weekly weight gains did not differ between group A and group B or between AGA and SGA. Length increment was greater in AGA than in SGA babies (0.94 +/- 0.02 vs 0.85 +/- 0.04 cm/week) but not significantly so (P less than 0.1), and in group B babies compared to group A babies (0.973 +/- 0.029 vs 0.83 +/- 0.037 cm/week) (P less than 0.01). Plasma pH was lower in group A (7.23 +/- 0.02) than in group B (7.30 +/- 0.02) and calcium ion activity higher (group A 2.72 +/- 0.04; group B 2.51 +/- 0.06 mEq/liter) between ages 20 and 29 days. Plasma magnesium was higher in group A (1.77 +/- 0.04 mEq/liter) than in group B (1.56 +/- 0.06 mEq/liter) from age 20 to 39 days. Inorganic phosphorus concentrations were consistently higher in group A than in group B, but the differences did not reach significance. Mean total protein concentrations did not rise above 4.5 g/100 ml and tended to be higher in babies of group A than of group B. Bone age was retarded in all babies. Radiographs available for 7 of 13 SGA infants were normal, whereas 6 of 11 radiographs of AGA babies showed some osteoporotic changes.     

Atypical auditory event-related potentials in preterm infants during the first year of life: a possible sign of cognitive dysfunction?

We assessed auditory event-related potentials in small-for-gestational-age (SGA; 850 +/- 258 g, 28.9 +/- 3.3 gestational wk; n = 15) and appropriate for gestational age (AGA; 1014 +/- 231 g, 26.9 +/- 1.9 gestational wk; n = 20) preterm infants and healthy term infants (n = 22). An oddball paradigm was used with a harmonic tone of 500-Hz frequency as the standard and of 750-Hz frequency as the deviant stimulus. The preterm infants were studied at 40 gestational wk and at 6 and 12 mo of corrected age, and the control subjects were studied at 2-4 d and at 3, 6, 9, 12, and 15 mo of age. The peaks of interest were the main positive peak (P350), the negative peaks at 250 ms (N250) and 650 ms (Nc), and the mismatch negativity at 200 ms (MMN). At term, the P350 in the preterm infants was similar to that of the newborn control subjects. In response to the deviant, the Nc was smaller in the SGA than in the AGA (P < 0.02) and control (P < 0.005) infants. The N250 amplitude was also lower in the SGA infants. At 12 mo, the MMN was observed in the control but not in the preterm infants, whose broad difference positivity correlated with the Bayley developmental index. The decreased Nc and N250 peaks in the SGA infants may suggest an increased risk for cognitive dysfunction. The broad difference positivity at 1 y of age may indicate atypical cortical auditory processing. Whether cognitive dysfunction can be predicted by these findings needs to be assessed in a study with extended follow-up.     

Intrauterine growth restriction and postnatal steroid treatment effects on insulin sensitivity in preterm neonates

OBJECTIVES: To study whether intrauterine growth restriction (IUGR) is associated with decreased sensitivity to the main fetal growth factor, insulin, and the effect of glucocorticoid therapy on insulin sensitivity in preterm infants. STUDY DESIGN: Newborn infants with a birth weight (BW) of< 1500 g were classified as appropriate for gestational age ([AGA], BW within +/- 1 SD, n = 10), or small for gestational age ([SGA], BW <-2 SD, n = 13); 5 AGA infants and 8 SGA infants received systemic steroids. An abbreviated modified minimal model test was performed, consisting of sequential blood samples for glucose and insulin assays, and intravenous infusions of 0.3 g/kg glucose and 0.02 U/kg regular human insulin. The insulin sensitivity index (S(I)) was calculated using a computer program. RESULTS: The basal insulin/glucose ratio (I/G) and S(I) did not differ between the AGA and SGA groups. Steroids did not influence the I/G nor the S(I) of AGA infants (10.2 +/- 6.7 vs 8.2 +/- 2.3), but decreased the S(I) in the SGA group (12.2 +/- 5.1 vs 5.3 +/- 2.7, P <.05). CONCLUSIONS: Insulin sensitivity of neonates can be measured by the modified minimal model. IUGR is not associated with impaired fetal glucose tolerance. Early neonatal steroid treatment decreases insulin sensitivity in SGA infants, which may contribute to their risk of having hyperglycemia.     

Growth of premature infants fed own mother's milk supplied with two milk formulas

The purpose of the authors in this article was to evaluate the effects of supplementing maternal milk with two different caloric formulas on the growth of premature newborns until they reached 40 weeks of post-conceptional age. Seventy premature infants weighing < 1750g at birth were randomized: 35 adequate for gestational age (AGA) and 35 small for gestational age received maternal milk and either a special preterm formula or a modified formula. Anthropometric measurements and clinical evaluations were used to determine the nutritional status and the postnatal growth of these infants, who were analyzed in six different moments: at maximum weight loss, at return to birth weight, at definite weight gain, when exclusively fed with formula, at 2000g, and when they reached 40 weeks of post-conceptional age. The AGA premature newborns on preterm formula had greater daily weight gain, cephalic circumference increase and growth. The SGA premature newborns on preterm formula had greater daily weight gain and cephalic circumference increase observed from the third week of life onward. The AGA premature newborns on modified formula had less weight gain and smaller increments in the cephalic circumference. The SGA premature on modified formula had the worst anthropometric results. The preterm formula was more efficient than the modified formula in promoting postnatal growth of AGA and SGA premature infants. We believe that, due to their special characteristics, SGA premature should receive individualized nutritional caloric planning     

ENERGY REQUIREMENTS AND UTILIZATION OF THE LOW BIRTHWEIGHT INFANT

Brooke, O.G. (Department of Child Health, St. George's Hospital, London, U.K.). Energy requirements and utilization of the low birthweight infant. Acta Paediatr Scand, Suppl. 296:67, 1982.—Energy balance data have been obtained on 24 well grown immature (AGA) infants (mean BW 1554 g) and 16 small-for-gestational age (SGA) infants (mean BW 1210 g) using bomb calorimetry on milk and excreta over 7–10 days periods. Simultaneous measurements of energy expenditure were made, using a Kipp diaferometer. The main findings were: At any particular gestational age, digestible energy (the proportion of dietary energy absorbed) was similar in AGA and SGA infants. Energy digestibility improved with maturation in all infants. Retained (metabolisable) energy was also similar in AGA and SGA infants, and averaged 65 % of the intake at 30 weeks, 78% at 32 weeks, and 85% at 40 weeks post-conceptional age. Weight gain was linearly correlated with metabolisable energy in AGA infants, an energy cost of 24 kJ/g (5.7 kcal). Maintenance energy requirement at zero weight gain in AGA infants was 270 kJ/kg/d (64 kcal/kg/d). Resting energy expenditure was significantly higher in SGA than in AGA infants, but postprandial metabolism was less. In spite of these differences, rates of weight gain were similar in the two groups of infants. Energy expended in activity was probably less than 20 % of the total energy turnover in both groups of infants. Energy balance was profoundly impaired by acidosis in all infants.     

Glycerol metabolism and triglyceride-fatty acid cycling in the human newborn: effect of maternal diabetes and intrauterine growth retardation.

Kinetics of glycerol metabolism and triglyceride/fatty acid cycling were quantified in 12 healthy, normal, appropriate-for-gestational-age (AGA) infants, eight small-for-gestational-age (SGA) infants, and five infants of insulin-dependent diabetic mothers (IDM) at less than 48 h of age. Stable isotope-labeled [2-13C]glycerol and [6,6-2H2]glucose in combination with indirect respiratory calorimetry were used. The tracers were used as constant rate infusion and steady state isotopic enrichment of glucose, glycerol, and bicarbonate was measured by mass spectrometric methods. After a 7- to 9-h fast, the plasma glucose, glycerol, and FFA concentrations were similar in the AGA and IDM groups. In the SGA group, the plasma glucose concentration was significantly lower than that in the AGA group throughout the study, but plasma FFA and glycerol concentrations were not different from those in the AGA infants. Plasma betahydroxybutyrate concentration was significantly elevated in the AGA group compared with IDM and SGA infants (AGA 0.59 +/- 0.39, SGA 0.35 +/- 0.09, IDM 0.33 +/- 0.21 mmol/L; mean +/- SD). The rate of appearance of glycerol was significantly elevated (p less than 0.05) in SGA infants (AGA 9.47 +/- 2.11, IDM 9.55 +/- 2.14, SGA 12.15 +/- 3.87 mumol/kg.min). Between 80 and 90% of glycerol turnover was converted to glucose, accounting for 20% of glucose turnover with no significant difference in the three groups. Approximately 35% of glycerol carbon was recovered in the bicarbonate (CO2) pool. Less than 5% of CO2 carbon was derived from glycerol. Estimation of triglyceride-fatty acid cycle revealed that the triglyceride energy mobilized was increased in SGA infants.(ABSTRACT TRUNCATED AT 250 WORDS)     

适于胎龄儿和小于胎龄儿小脑发育的对比研究

目的 探讨适于胎龄儿（AGA）和小于胎龄儿（SGA）的小脑发育是否存在差异。方法 选取165例胎龄25~40⁺⁶周的AGA和105例相应胎龄的SGA纳入研究。于新生儿出生24~48 h内采用超声测量小脑横径、小脑蚓部高度、小脑蚓部面积、小脑蚓部周长、小脑横径切面小脑面积、小脑横径切面小脑周长。采用Pearson相关分析法进行各测量值与胎龄关系的分析。结果 不论AGA还是SGA,小脑各测量值和胎龄均呈正相关（r=0.50~0.81,P < 0.05）。AGA和SGA各测量值在胎龄25~27⁺⁶周、28~30⁺⁶周、31~33⁺⁶周亚组中的比较差异无统计学意义（P > 0.05）,但在胎龄34~36⁺⁶周、37~40⁺⁶周亚组中,SGA的各测量值均明显低于AGA（P < 0.05）。结论 胎龄 < 34周SGA的宫内小脑发育与同胎龄的AGA类似,而≥34周SGA的宫内小脑发育落后于AGA。     

Factors associated with weaning in full term and preterm infants

BACKGROUND: The optimal age for the introduction of solid foods (weaning) in infants is poorly researched yet may have implications for both short and longer term health. Many parents do not comply with current guidelines. OBJECTIVE: To determine and compare the age at weaning in term appropriate size for gestational age (AGA), small for gestational age (SGA), and preterm infants, and factors associated with weaning age in these groups. DESIGN: Data from > 2000 infants from seven prospective randomised trails conducted between 1990 and 1997 were used to address the objectives. RESULTS: Most infants, term AGA, SGA, or preterm, received solids before 4 months of age. Only 2% of term infants were exclusively breast fed to 6 months of age. Formula fed infants received solids on average two weeks earlier than breast fed infants. Preterm infants were significantly more likely, and term SGA infants less likely, to receive solids at both 6 and 12 weeks after term than term AGA infants. Weight at 6 weeks of age was a stronger predictor of earlier weaning than either birth weight or weight gain from birth to 6 weeks in term infants. In preterm infants, formula feeding and maternal smoking were associated with earlier weaning. CONCLUSIONS: Infants born in the mid 1990s were weaned on average earlier than the 4 months recommended by the Department of Health. Earlier weaning was associated with less positive health behaviours. Further research is required to provide evidence based weaning guidelines, including specific advice for SGA and preterm infants, and to investigate longer term consequences of weaning practices.     

Doppler velocimetry in cerebral vessels of small for gestational age infants.

Using the duplex Doppler system, blood velocity was measured serially at two sites of the anterior cerebral artery (ACA) and in the middle cerebral artery (MCA) during the first 3 days of life, in eight term, small for gestational age (SGA) infants (birthweight, 2179 +/- 230 g; mean +/- S.D.), and 13 term, appropriate for gestational age (AGA) infants (3376 +/- 441 g). All infants in both groups had normal Apgar scores and none manifested signs of respiratory distress. At 1 h post partum, the average MCA mean velocity in the SGA group (25.8 +/- 6.9 cm/s) was higher than that in the AGA group (19.6 +/- 5.7 cm/s), whereas the average values of the two ACA sites did not differ between the groups. A significantly increased value of the average mean velocity as compared to the value at 4 h post partum was reached earlier in the AGA group at all three vessel sites. The pulsatility index (as defined by Gosling) was lower at all vessel sites up to 72 h in the SGA group. Pulse pressure was significantly lower in the SGA group due to increased diastolic blood pressure. We suggest the results imply a state of cerebral vasodilation in the SGA infants and a poor ability to respond with an increased perfusion in the frontal regions supplied by the ACA. Changes in blood pressure and cerebral haemodynamics appear to exist in SGA infants in the absence of postnatal hypoxia which might explain the vulnerability of the growth-retarded infant to perinatal hypoxia.     

Differential effects of intrauterine and postnatal brain growth failure in infants of very low birth weight

We investigated the contribution of brain growth failure to outcome in infants of very low birth weight (VLBW; less than 1.5 kg) who were appropriate for gestational age (AGA; n = 379) or small for gestational age (SGA; n = 102). Growth was assessed at birth, term, and 8 and 20 months' corrected age and results of a Bayley Mental Developmental Index (MDI) and neurologic examination were evaluated at 20 months of age. Both groups had similar 20-month MDI scores (93 vs 90) and similar rates of neurologic impairment (14% vs 10%). More SGA infants (25%) than AGA infants (14%) had a subnormal head circumference at 8 months' corrected age, indicating failure to catch up in head growth. Subnormal head size at 8 months predicted the 20-month MDI score for both groups. However, multivariate analysis indicated that, whereas subnormal 8-month head size was directly associated with the MDI score in AGA children, in SGA children 8-month head size was not significantly related to the MDI score when neonatal illness, neurologic impairment, socioeconomic status, and race were controlled for. We conclude that in AGA VLBW infants, subnormal head size at 8 months results from major neonatal illness and has adverse later effects. In SGA infants, subnormal head size at 8 months has many causes, including growth retardation in utero, which may not have an adverse effect on outcome; if subnormal head size is superimposed with neonatal illness, a poorer outcome is likely.