Effects of symmetric and asymmetric fetal growth on pregnancy outcomes

OBJECTIVE: To assess the prevalence of head circumference to abdomen circumference (HC/AC) asymmetry among small for gestational age (SGA) fetuses, and to determine the likelihood of adverse outcomes among asymmetric and symmetric SGA infants compared with their appropriate for gestational age (AGA) counterparts. METHODS: In a retrospective cohort study, we analyzed consecutive live-born singletons of women who had antepartum sonography within 4 weeks of delivery and delivered between January 1, 1989 and September 30, 1996. A gestational age-specific HC/AC nomogram was derived from our sonographic database of 33,740 nonanomalous live-born singletons. Asymmetric HC/AC was defined as greater than or equal to the 95th percentile for gestational age. RESULTS: Among 1364 SGA infants, 20% had asymmetric HC/AC and 80% were symmetric. Asymmetric SGA infants were more likely to have major anomalies than symmetric SGA infants or AGA infants (14% versus 4% versus 3%, respectively; P <.001). After exclusion of anomalous infants, pregnancy-induced hypertension at or before 32 weeks' gestation and cesarean delivery for nonreassuring fetal heart rate were more common in the asymmetric SGA than the AGA group (7% versus 1% and 15% versus 3%, respectively; both P <.001). A neonatal outcome composite, including one or more of respiratory distress, intraventricular hemorrhage, sepsis, or neonatal death, was more frequent among asymmetric SGA than AGA infants (14% versus 5%, P =.001). Symmetric SGA infants were not at increased risk of morbidity compared with AGA infants. CONCLUSION: The minority of SGA fetuses with HC/AC asymmetry are at increased risk for intrapartum and neonatal complications.     

Perinatal correlates and neonatal outcomes of small for gestational age infants born at term gestation

OBJECTIVE: We sought to examine the current perinatal correlates and neonatal morbidity associated with intrauterine growth failure among neonates born at term gestation. STUDY DESIGN: We compared 372 small for gestational age (SGA, birth weight <10th percentile) infants born at term gestation to 372 appropriate for gestational age controls (AGA, birth weight 10th to 90th percentile) matched by sex, race, and gestational age within 2 weeks. RESULTS: Compared with AGA controls, significant (P < .05) maternal risk factors for SGA status included single marital status (59% versus 53%), lower prepregnancy weight (144 +/- 41 lbs versus 153 +/- 40 lbs), lower weight gain during pregnancy (29 +/- 15 lbs versus 33 +/- 15 lbs), smoking (25% versus 17%), hypertension (14% versus 7%), and multiple gestation (9% versus 2%). Mothers of SGA infants were more likely to undergo multiple (>or=3) antenatal ultrasound evaluations (19% versus 7%), biophysical profile monitoring (11% versus 4%), and oxytocin delivery induction (28% versus 16%) (P < .05). Pediatrician attendance was more common among SGA deliveries (50% versus 37%, P < .05). SGA infants had significantly higher rates of hypothermia (18% versus 6%) and symptomatic hypoglycemia (5% versus 1%). These neonatal problems remained significant even when medical or pathologic causes of intrauterine growth failure, including pregnancy hypertension, multiple gestation, and congenital malformations, were excluded. CONCLUSION: Despite higher rates of pregnancy complications among mothers of SGA infants, the rates of neonatal adverse outcomes are low. However, SGA infants remain at risk for hypothermia and hypoglycemia and require careful neonatal surveillance.     

Altered cord serum lipid levels associated with small for gestational age infants

OBJECTIVE: To determine whether small for gestational age (SGA) infants show changes in lipid metabolism that could distinguish growth-restricted subpopulations. METHODS: Sera from the arterial cord blood from 38 SGA infants were analyzed for apolipoprotein A-I level, total lipid content, and distribution of those lipids as triglycerides, diglycerides, free fatty acids, and phospholipids. Comparisons were made between appropriate for gestational age (AGA) controls (n = 25), SGA infants with a ponderal index below the tenth percentile (SGA I, n = 20), and SGA infants with a ponderal index above the tenth percentile (SGA II, n = 18). RESULTS: Total cord serum lipid content was markedly decreased in all SGA infants compared with AGA infants (2.8 times lower). Although SGA infants showed total lipid concentration decreases, SGA I and SGA II infants showed distinct characteristics. Infants in the SGA I group had higher triglyceride levels (1.8 times higher) and lower free fatty acid levels (1.4 times lower), compared with AGA infants (P < .001). The lipid subclass distribution in SGA II infants was not significantly different from that in AGA infants, with the exception of an increase in triglyceride concentrations (1.3 times higher). Although the 22-kD placenta-derived apolipoprotein A-I was similar in all groups, the level of fetal liver-derived 28-kD apolipoprotein A-I was 6.5 times lower in SGA I infants than in AGA or SGA II infants (P < .001). CONCLUSION: The SGA I infants appeared to have impaired utilization of circulating triglycerides, consistent with peripheral adipose depletion. Diminished fetus-derived apolipoprotein A-I levels with normal levels of placenta-derived apolipoprotein A-I levels might indicate a defect in the production or secretion of apolipoproteins associated with growth restriction.     

Bone ultrasound velocity in small- versus appropriate-for-gestational age preterm infants.

OBJECTIVE: To compare bone status of small-for-gestational age (SGA) versus appropriate-for-gestational age (AGA) newborn preterm infants. STUDY DESIGN: Tibial speed of sound (SOS) was measured in 144 infants categorized as SGA or AGA using the reference tables of Lubchenco et al. and Alexander et al. RESULTS: By the Lubchenco tables, 22% of infants were SGA and 75% were AGA. The mean gestational ages of SGA and AGA were similar (33.3+/-2.6 and 32.5+/-2.4 weeks, respectively, P = 0.09); however, SGA infant birth weights were lower (1329+/-392 and 1829+/-481 g, respectively, P<0.001). SOS values were higher for SGA versus AGA infants (3098+/-135 and 3003+/-122 m/s, respectively. P<0.001). Use of the Alexander tables yielded a twofold increase in the percent of infants categorized as SGA; SOS values remained significantly greater for SGA infants (P<0.001). CONCLUSION: Higher tibial SOS values in SGA versus AGA infants indicate greater bone strength.     

Plasma volume findings in patients with mild pregnancy-induced hypertension

With the Evans blue dye-dilution technique, plasma volume was serially measured at 29 to 33 weeks' and 34 to 40 weeks' gestation in 74 pregnant women with documented mild pregnancy-induced hypertension (PIH) and 25 well-matched normotensive primigravid women. The relationship of plasma volume to clinical course, perinatal outcome, and other laboratory findings was subsequently analyzed. The patients with mild PIH were categorized into two groups based on infant outcome: appropriate for gestational age (AGA) and small for gestational age (SGA). The mean age, height, and hematocrit of the study and control patients were similar. The group of patients with mild PIH had significantly higher mean arterial blood pressures and uric acid levels (p less than 0.001). There was no difference in mean plasma volume findings between the normotensive group and the mild PIH group delivered of AGA infants. Plasma volume was reduced only in pregnancies with mild PIH with delivery of SGA infants. It is concluded that plasma volume is not reduced in most patients with mild PIH. However, plasma volume might be useful in identifying a subgroup of patients with mild PIH at risk for delivering an SGA infant.     

The preterm small-for-gestational age infant: a two-year follow-up study.

Previous investigators have reported unfavorable neurologic and developmental outcome of small-for-gestational age (SGA) infants (birth weight less than 1,500 grams born at term or at less than 30 weeks. of gestation. Since obstetrical considerations for the delivery of a SGA fetus often arise between 30 and 38 weeks, the outcome of these survivors becomes a relevant issue. In 1975 and 1976, twenty-eight of 47 such infants survived and 21 were followed sequentially during the first two years. Their birth weight was 1,220 +/- 195 grams (mean +/- S.D.) and the gestation 33.4 +/- 2 weeks. Each SGA infant was paired with a birth weight-matched appropriate-for-gestation (AGA) infant whose birth weight was 1,195 +/- 190 grams and gestation 29 +/- 2 weeks. The weight, length, and head circumference of the SGA infants attained the tenth percentile by 6 to 8 months and were similar to the AGA group. Quarterly neurologic examinations showed similar findings during the first year in the two groups. At 2 years, two SGA (diplegia) and one AGA (hemiplegia) infants were abnormal. The quarterly Bayley scores of the SGA infants were lower during the first 18 months but at 24 months, the two groups had similar scores. The favorable outcome in preterm SGA infants weighing less than 1,500 grams may serve as useful information in making clinical decisions for the management of mothers with suspected intrauterine growth retardation.     

Plasma adrenomedullin levels in pregnancies with appropriate for gestational age and small for gestational age infants.

AIMS: To evaluate whether maternal and fetal plasma adrenomedullin levels in pregnancies with small for gestational age (SGA) infants are different from those in pregnancies with appropriate for gestational age (AGA) infants. METHODS: Maternal and fetal circulating adrenomedullin levels were compared between 62 pregnancies with AGA (43 delivered vaginally and 19 delivered by elective cesarean section) and 28 pregnancies with SGA (20 delivered vaginally and 8 delivered by elective cesarean section) at birth. Plasma adrenomedullin levels were measured from maternal and cord venous blood samples using a radioimmunoassay. Umbilical artery blood pH was also measured. RESULTS: There were no significant differences for maternal total adrenomedullin levels, mature adrenomedullin levels, and its ratio among the groups. There were also no significant differences for fetal total adrenomedullin levels, mature adrenomedullin levels, and its ratio among the groups. In the AGA group delivered vaginally, fetal mature/total adrenomedullin ratio (mean +/- standard error, 16.6 +/- 0.7%) was significantly higher than the maternal ratio (13.8 +/- 0.6%) (p < 0.05). In the SGA group delivered vaginally, fetal mature/total adrenomedullin ratio (18.5 +/- 1.0%) was also significantly higher than the maternal ratio (14.5 +/- 0.6%) (p < 0.05). There was no significant difference in umbilical artery blood pH among the groups. CONCLUSIONS: These results suggest that maternal and fetal plasma circulating adrenomedullin levels may play a role in maternal and fetal cardiovascular adaptation during delivery in pregnancies with both AGA and SGA infants.     

Comparison of umbilical blood gas and acid-base status of small-for-date and normal Chinese newborns.

A prospective study of umbilical arterial blood gas in appropriate-for-gestational-age (AGA) and small-for-gestational-age (SGA) babies was performed at our hospital from August 1989 to July 1990. A total of of 512 cases were included, 432 cases in the AGA group and 80 cases in the SGA group, with gestational ages ranging from 26 to 42 weeks. Umbilical arterial blood was collected immediately after delivery of the newborns. Comparisons of maternal age, gestational age, birth body weight and body length of infants. Apgar scores at one minute and five minutes, cord arterial blood pH, pO2, pCO2, base excess, bicarbonate, total CO2, O2 saturation and O2 content between the AGA and SGA groups were taken into account. Our results demonstrated significant differences in birth body weight, birth body length, Apgar scores at one minute and five minutes and gestational age in the SGA group compared with those in the AGA group. The parameters of cord arterial blood gas were not correlated with gestational age in either group. The mean pH value in the AGA group (7.30 +/- 0.05) was higher than that in the SGA group (7.28 +/- 0.08). The same trend of difference was also noted between the AGA (7.30 +/- 0.04) and SGA (7.27 +/- 0.07) babies who were delivered by Cesarean section (p < 0.05). The latter results imply a more academic state in SGA babies which is independent of labor. Prepartum asphyxia plays an important role in determining the prognosis of SGA babies. We suggest routine umbilical cord blood gas and acid-base analysis at delivery to assess fetal asphyxia.     

Comparison of late-second-trimester nonstress test characteristics between small for gestational age and appropriate for gestational age infants

OBJECTIVE: To compare electronic fetal heart rate (FHR) monitoring characteristics between appropriate for gestational age (AGA) fetuses and small for gestational age (SGA) fetuses and to determine whether SGA fetuses have specific abnormalities at second-trimester electronic fetal monitoring (EFM), using nonstress test. METHODS: Among 953 children born from 1993-1996, we identified 500 singleton infants born after 36 weeks' gestation of uncomplicated pregnancies in whom second-trimester (24-27 weeks' gestation) EFM records were obtained. Individual components of FHR patterns (baseline rate, baseline FHR variability, presence of acceleration [at least 10 beats per minute for at least 10 seconds], and periodic or episodic deceleration [at least 25 beats per minute for at least 15 seconds]) and birth characteristics were compared between AGA and SGA infants, or between pregnancies with or without second-trimester decelerations. RESULTS: Among 500 infants, 443 were AGA and 57 SGA; 105 had and 395 did not have second-trimester decelerations. Baseline FHR variability (12.9+/-3.2 beats per minute) in SGA fetuses was significantly higher than variability (10.3+/-3.4 beats per minute) in AGA fetuses (P<.001). Small for gestational age fetuses were significantly more likely to have second-trimester decelerations than AGA fetuses (33.3% vs. 19.4%, P<.05). There were no significant differences in baseline rate and accelerations between AGA and SGA infants. Small for gestational age infants were more frequent in pregnancies with second-trimester decelerations, compared with those without second-trimester decelerations (18.1% vs. 9.6%, P<.05). Baseline FHR variability in pregnancies with second-trimester decelerations was significantly higher than in pregnancies without second-trimester decelerations (12.2+/-3.7 vs. 10.0+/-3.1 beats per minute, P<.001). CONCLUSION: Periodic or episodic decelerations and increased FHR variability during late second-trimester EFM were associated with an increased risk of SGA birth weight.     

Maternal and umbilical venous adrenomedullin and nitric oxide levels in intrauterine growth restriction.

OBJECTIVE: To verify whether adrenomedullin (AM) and nitric oxide (NO) concentrations are changed in the maternal and fetal circulation in pregnancies complicated by intrauterine growth restriction (IUGR) compared to normal pregnancies, and to determine any relationship between them. METHODS: Forty-six small for gestational age (SGA) and 34 appropriate for gestational age (AGA) infants were included in the study. Umbilical and maternal venous AM and NO concentrations were determined. RESULTS: Umbilical NO concentrations in SGA infants (mean +/- SD; 176.2 +/- 75.8 micromol/L) were significantly greater than in AGA infants (143.4 +/- 39.2 micromol/L) (p = 0.015). However, umbilical AM concentrations were similar in SGA and AGA infants with 14.2 +/- 4.4 pmol/mL and 14.5 +/- 6.2 pmol/mL, respectively (p > 0.05). There was no relationship between NO and AM levels in umbilical blood (r = 0.09, p = 0.40). No difference was found between either AM or NO levels in the maternal plasma of the two groups. CONCLUSIONS: We suggest that NO is increased in the fetoplacental circulation in SGA infants probably as a response to decreased blood flow, whereas AM is not. Additionally, increased NO in the fetoplacental circulation was found to be independent from AM secretion.     

Outcome at 5 years of age of SGA and AGA infants born less than 28 weeks of gestation

The objective of this study was to compare the outcomes at 5 years of age of SGA and AGA children born < 28 weeks of gestation. The method used was a longitudinal follow-up of a cohort of 37 dyads of SGA and AGA infants matched by gestational age (GA), gender, and date of delivery. Mean GA was 26+/-1.2 weeks, and BW was 638+/-77 g for SGA and 833+/-134 g for AGA (P < 0.0001). The SGA infants remained lighter at 3, 24, and 60 months. Their head circumference was statistically smaller at 3 and 60 months, and their length remained lower but no longer statistically significant. There was no difference after the second year of life between SGA and AGA children in the need for rehospitalization (16% versus 11%) and the incidence of medical problems such as Otitis (38% versus 41%) and asthma (24% versus 30%). SGA exhibited more neurodevelopmental deficits (41% versus 30%) and severe handicaps, including CP, blindness, deafness, and mental retardation (22% versus 14%). Those deficits were seen predominantly in association with microcephaly, which was more prevalent in the SGA group. We conclude that the combination of severe prematurity and intrauterine growth retardation constitutes a serious developmental handicap and predisposes to physical and developmental delays. The presence of microcephaly further aggravates the prognosis.     

Doppler measurements on branches of the uterine artery in normal, hypertensive and growth-retarded pregnancies

The quality and reliability of pulsed Doppler recordings from branches of the uterine artery were tested by studying 37 normotensive pregnancies and 14 complicated by pregnancy-induced hypertension (PIH) lasting for several minutes. The coefficients of variation of mean velocity and A/B ratio (= peak systolic/end diastolic velocity) were 0.06 and 0.08, respectively. Thus, calculations of A/B ratio from a limited number of heart beats should be reliable. Calculations were then made from uterine artery Doppler recordings in 65 normotensive pregnancies and 32 with PIH. A significantly higher A/B ratio was found in the PIH group. Among the normotensives, no statistically significant difference in A/B ratio was found between those who gave birth to appropriate-for-gestational-age (AGA) and small-for-gestational-age (SGA: less than 10th centile) infants. In the PIH group a significant difference was found; A/B: 1.95 versus 1.78 in the SGA and AGA groups, respectively. The latter was still significantly higher than the normotensive (= 1.60). Two PIH subgroups with equivalent blood pressures and proteinuria, but who gave birth to AGA or SGA infants, were compared. A/B ratio from the latter was significantly higher. These findings show that PIH is associated with increased uteroplacental vascular resistance; increased vascular pathology is associated with fetal growth retardation.     

Brain growth in preterm infants is affected by the degree of growth restriction at birth

Abstract

Objective: Documentation of examination of brain structural development by magnetic resonance imaging (MRI) beyond the neonatal period is scarce for both preterm and small for gestational age (SGA) infants.

Aim: To investigate structural brain development during infancy in preterm children born SGA by MRI.

Methods: A total of 205 preterm infants, 139 appropriate for gestational age (AGA) and 66 SGA, of which 33 had birth weight (BW)?<?3rd percentile and 33 had BW 3rd–10th percentile, were examined prospectively by brain MRI at the corrected age of 5 months. The total volume of the brain, ventricles and cerebellum, the area of vermis and corpus callosum, and the height of the pituitary, mesencephalon and pons were estimated on MRI.

Results: Brain volume was smaller in the SGA?<?3rd percentile infants, independent of other perinatal factors. Chronic lung disease was an independent predictor of low brain volume. Pituitary height was greater in SGA?<?3rd percentile than in AGA infants. The corpus callosum area was less in SGA?<?3rd percentile than in SGA of 3rd–10th percentile infants.

Conclusions: Preterm infants born SGA with BW?<?3rd percentile had differences in brain structural measurements at the corrected age of 5 months, compared with preterm AGA infants, which could have implications for their neurocognitive development.     

Placental ratio in pregnancies at different risk for intrauterine growth

Objective: We have analyzed the placental/birthweight ratio in women at increased risk of intrauterine growth retardation and pregnancy-induced hypertension and in women with pregnancy ‘complicated’ by these conditions. Study design: A total of 89 women with small gestational age (SGA) infants, 355 with appropriate gestational age infants (200 in the uncomplicated pregnancy group) and 28 with large for gestational age (LGA) infants were considered. Results and Conclusion: The mean placental weight showed a significant increase from the SGA to the LGA in the two groups. The placental ratio tended to increase from the LGA group to the SGA one both in infants of women with uncomplicated pregnancy and with pregnancy complicated by intrauterine growth retardation or pregnancy-induced hypertension; these findings were statistically significant.     

Association between early postnatal weight loss and death or BPD in small and appropriate for gestational age extremely low-birth-weight infants.

OBJECTIVE: To examine the association between weight loss during the first 10 days of life and the incidence of death or bronchopulmonary dysplasia (BPD) in small for gestational age (SGA) and appropriate for gestational age (AGA) extremely low-birth-weight infants. DESIGN/METHODS: This is a retrospective analysis of a cohort of ELBW (birth weight <1000 g) infants from the NICHD Neonatal Research Network's database. The cohort consisted of 9461 ELBW infants with gestational age of 24-29 weeks, admitted to Network's participating centers during calendar years 1994-2002 and surviving at least 72 h after birth. The cohort was divided into two groups, 1248 SGA (with birth weight below 10th percentile for gestational age) and 8213 AGA (with birth weight between 10th and 90th percentile) infants. We identified infants with or without weight loss during the first 10 days of life, which we termed as 'early postnatal weight loss' (EPWL). Univariate analyses were used to predict whether EPWL was related to the primary outcome, death or BPD, within each birth weight/gestation category (SGA or AGA). BPD and death were also analyzed separately in relation to EPWL. Logistic regression analysis was done to evaluate the risk of death or BPD in SGA and AGA groups, controlling for maternal and neonatal demographic and clinical factors found to be significant by univariate analysis. RESULTS: SGA ELBW infants had a lower prevalence of EPWL as compared with AGA ELBW infants (81.2 vs 93.7%, respectively, P<0.001). In AGA infants, univariate analysis showed that death or BPD rate was lower in the group of infants with EPWL compared with infants without EPWL (53.4 vs 74.3%, respectively, P<0.001). The BPD (47.2 vs 64%, P<0.001) and death (13.8 vs 32.9%, P<0.001) rate were similarly lower in the EPWL group. The risk-adjusted odds ratios (ORs) showed that EPWL was associated with lower rate of death or BPD (OR 0.47, 95% CI: 0.37-0.60). In SGA infants, on univariate analysis, a similar association between EPWL and outcomes was seen as shown in AGA infants: death or BPD (55.9 vs 75.2%, P<0.001), BPD rate (48.3 vs 62.1%, P=0.002) and rate death (19 vs 40.8%, P<0.001) for those with or without EPWL, respectively. Multiple logistic regression showed that as in AGA ELBW infants, EPWL was associated with lower risk for death or BPD (OR 0.60, 95% CI: 0.41-0.89) among SGA infants. CONCLUSIONS: SGA infants experienced less EPWL when compared with their AGA counterparts. EPWL was associated with a lower risk of death or BPD in both ELBW AGA and SGA infants. These data suggest that clinicians who consider the association between EPWL and risk of death or BPD should do so independent of gestation/birth weight status.     

Birth weight and gestational age standards based on regional perinatal network data: an analysis of risk factors

The most frequently used set of gestational age-birth weight curves in the United States is the Colorado (C) standard published in 1963. To investigate the usefulness of this standard in an urban population at sea level, we examined the birth weight vs gestational age data from 56,675 singleton liveborn infants born between 1982 and 1985 in the University of Illinois (UI) perinatal network of 13 hospitals. Between 32 and 42 weeks, the UI 10th, median, and 90th percentile weights were significantly higher than those of Colorado. At term gestations the Colorado 10th and 90th percentile weights were the same as the UI 3rd and 80th percentile weights, respectively. Using the UI and Colorado standards for 10th and 90th percentile weights, the study sample was divided into five subgroups. To evaluate the risk prevalence, we examined the frequency of neonatal death, low, and very low Apgar scores (below seven and three, respectively), respiratory distress, maternal hypertension, and diabetes in the five subgroups. The highest frequency of adverse factors was seen in infants classified as small for gestational age (SGA) by both standards, but overall, the size-for-gestation grouping was better accomplished using the UI rather than the C standard. In 9188 infants (16.2%) classified into wrong weight-gestation subgroups using the Colorado standard, the prevalence of actual risk factors was at variance with the group to which they were assigned. This included 3632 (6.4%) SGA infants who were grouped as appropriate for gestational age (AGA), and 5556 (9.8%) AGA infants grouped as large for gestational age.(ABSTRACT TRUNCATED AT 250 WORDS)     

Significance of antenatal detection and the choice of the delivery place of severely small for gestational age fetuses.

The outcome of 72 severely small for gestational age (SGA) fetuses (birthweight below the 2.5 percentile) was compared with the outcome of 144 next-born average for gestational age (AGA) fetuses (birthweight between the 10th and the 90th percentile). Both these groups were matched for gestational age, sex, and maternal parity. The purpose of SGA versus AGA comparison was to allow for discussion on the significance of prenatal diagnosis of severely SGA fetuses in planning an appropriate delivery setting. In this study, SGA fetuses were more often delivered abdominally because of suspected fetal distress; this was especially true of practically all the pre-term SGA fetuses. Severely SGA newborns had more acidosis and they more often needed neonatal intensive care unit (NICU) placement than their AGA counterparts. From these observations, it can be concluded that antenatal detection of severely SGA fetuses seems to be important. Delivery of the severely SGA fetus, moreover, should be scheduled in the hospital setting, where NICU facilities are readily available.     

Impact of being small-for-gestational age on survival and long-term outcome of extremely premature infants born at 23-27 weeks' gestation

AIM: To evaluate factors affecting survival and long-term outcome of extremely premature infants and to determine whether small for gestational age (SGA) status is an additional risk factor. METHODS: Survival was analyzed in 193 infants born between 23 and 27 weeks of gestational age (GA) and compared between SGA (n=43) and appropriate for gestational age (AGA) infants. Long-term outcome was assessed in 123 infants at six years of chronological age by neurological evaluation and cognitive tests. RESULTS: The long-term survival rates were 72.1% for SGA and 84.0% for AGA infants. Significant independent factors affecting survival were GA (OR 1.79 for one week advance, 95% CI 1.36-2.34) and SGA (OR 0.42, 95% CI 0.18-0.997) in comparison with AGA. There were no significant differences in rates of cerebral palsy or mental retardation, 12.0% and 24.0% in SGA, 14.3% and 17.3% in AGA, respectively. Fifty-two percent of SGA and 70% of AGA infants had intact long-term outcome. The perinatal factor found to affect the intact long-term outcome was RDS with surfactant therapy (OR 0.17, 95% CI 0.07-0.45). CONCLUSION: SGA status as well as short gestation had significant effects on survival. Respiratory complications after birth had a larger detrimental effect on long-term outcome than whether the infant was SGA or AGA.     

瘦素在胎盘组织中的表达及其与新生儿体重的关系

目的探讨瘦素在胎盘组织中的表达及其与新生儿体重的关系.方法采用放射免疫法(RIA)检测100例足月孕妇静脉血及其新生儿脐血瘦素水平,根据新生儿出生体重分为大于胎龄儿(LGA)组19例,适于胎龄儿(AGA)组65例,小于胎龄儿(SGA)组16例,同时采用逆转录-聚合酶链反应(RT-PCR)技术,检测41例胎盘组织中瘦素mRNA表达水平.结果(1)胎盘组织中瘦素mRNA表达水平为0.97±0.04,与新生儿体重呈显著正相关关系(r=0.43,P＜0.01).其中LGA组(1.01±0.03)显著高于AGA组(0.97±0.02),SGA组(0.93±0.03)显著低于AGA组,差异均有极显著性(P＜0.01).(2)母血瘦素水平为(14.22±7.66)μg/L,与新生儿体重无相关关系(r=0.11,P＞0.05).(3)新生儿脐血瘦素水平为(7.58±5.15)μg/L,与新生儿体重呈显著正相关关系(r=0.57,P＜0.01),其中LGA组脐血瘦素水平为(13.38±6.75)μg/L,显著高于AGA组的(7.40±4.45)μg/L,SGA组为(2.79±1.54)μg/L,显著低于AGA组,差异有极显著性(P＜0.01).结论脐血及胎盘组织中瘦素水平与胎儿生长发育状态密切相关;母血瘦素水平与新生儿体重无关;孕期胎儿瘦素的重要来源是胎盘组织.     

Weights of placentae from small-for-gestational age infants revisited

The objective of the study was to investigate the association between placental weight and birthweight in appropriate (AGA) and small for gestational age (SGA) infants. Placental weight, birthweight and their ratio in chromosomally normal singleton pregnancies with SGA (n=1569) and AGA (n=15 047) infants were compared, and their determinants were studied by logistic regression. SGA infants had 24 per cent smaller placentae than AGA infants when gestational age was used as a covariate. Placental actual weight was also lower in SGA infants than in AGA infants of the same birthweight (P< 0.001). SGA infants had smaller placentae than the controls, suggesting that fetal growth depends on the actual weight of the placenta. Future studies should evaluate whether growth restriction could be reversed by therapeutic approaches increasing placental weight.