Growth retardation in preterm infants

This paper combines earlier results on the relation between birthweight and gestational age, and the relation between fetal weight and ultrasound measurements of the fetal biparietal diameter (BPD) and mean abdominal diameter (AD) to investigate whether preterm infants (viewed as a group) are smaller than unborn fetuses of the same gestational age. The birthweight distribution for each sex at 223 and 258 days gestation was derived from the birthweight-for-gestational age charts based on 3888 newborn infants. The sex-specific intrauterine weight distribution was estimated from ultrasound measurement of the fetal BPD and AD performed on randomly selected fetuses of gestational age 223 and 258 days. The birthweights were lower than the intrauterine weights, especially early in pregnancy and for female infants. Thus, the 10th birthweight centile for girls at day 223 corresponds to the 4th centile of the 'true' intrauterine weight, and the 'true' intrauterine 10th centile corresponds to the 25th centile birthweight at day 223.     

Estimation of fetal weight in the third trimester by ultrasound

A method to estimate the intrauterine fetal weight by use of ultrasound measurements of the fetal biparietal diameter (BPD) and the abdominal diameter (AD) is presented. From a consecutive series of single pregnancies the 238 pregnancies (3% of the hospital population) with ultrasound measurements obtained within 4 days before delivery were used in the estimation of birth weight. In addition, the estimated formula was applied on a test material consisting of 100 similarly selected pregnancies from the same hospital. To evaluate the expected selection effects, the birth weight for gestational age in the study group was compared with birth weight for gestational age in the total population. The weight could be estimated as 0.0351 X AD1.65 X BPD0.69 X exp(0.00196 X gestational age). Thus, the actual birth weight was within 83-120% of the estimated weight (95% prediction limits), with a residual coefficient of variation of about 9%. The gestational age could be omitted without major influence on the weight prediction. When applying the formula on the test material, 70% of the actual weights deviated less than 10% from the estimated fetal weight, but a tendency towards a slight overestimation of the weight for light for gestational age infants was found.     

A randomized study of fetal abdominal diameter and fetal weight estimation for detection of light-for-gestation infants in low-risk pregnancies

Summary. A total of 2771 pregnant women with gestational age esti-mated by ultrasound measurement of the fetal biparietal diameter (BPD) before the 22nd week of gestation were re-examined by ultrasound in the 32nd and 37th week of pregnancy at which time the fetal BPD and abdominal diameter (AD) were measured. An additional examination was performed at 34 weeks if the fetal weight in the 32nd week was estimated to be less than 95% of the expected mean weight. Light-for-gestational age (LGA) was suspected if the estimated birth-weight was less than 85% of the expected mean birthweight. This applied to 186 uncomplicated pregnancies in which there was no clinical suspicion of poor intrauterine growth. These pregnancies were randomly allocated to a treatment group (AD and estimated weight reported) or to a control group (AD and estimated weight withheld). Induction of labour was significantly more common in the treatment group (41%) than in the control group (15%). No statistically significant difference was found in the use of instrumental vaginal delivery or caesarean section. There was a Suggestion of marginal benefit in terms of neonatal morbidity but this was not statistically significant.     

Growth in breech presentation. Ultrasound and post-partal assessment of growth in 225 fetuses presenting by the breech in the 33rd gestational week

225 fetuses with ultrasonically determined gestational age were shown by ultrasound to be in breech presentation in the 33rd gestational week. The biparietal diameter (BPD) and the mean of two perpendicular abdominal diameters (AD) were measured ultrasonically in gestational weeks 33, 35, and 38. Based on these measurements, fetal weight was estimated and compared with weight, length, and head circumference at birth and at 18 months of age. 42% of the fetuses were born in breech presentation (breech group) and 58% in vertex presentation (vertex group). The mean birth weight corrected for gestational age was 4.9% lower in the breech group than in the vertex group, which corresponds to the lower intra-uterine values of BPD and AD found in the breech group. The weight differences at birth still persisted at 18 months of age. There were no differences between the groups regarding head circumference or length, either at birth or at 18 months of age.     

Intrauterine growth in twin pregnancies: prediction of fetal growth retardation

In 80 consecutive twin pregnancies, prenatal measurements of fetal biparietal diameter (BPD) and abdominal diameter were made and growth curves were calculated using routine ultrasound examinations. Nineteen percent of the infants were growth retarded. Growth retardation was found in both fetuses in four pregnancies and in one fetus in 22 other pregnancies. Linear regression analysis between birth weight and gestational age showed the standard deviation of birth weight to be proportional to gestational age. A more linear growth curve also was found when the mean fetal weight was calculated by use of the BPD and abdominal diameter measurements in the formula developed for singletons. The estimated weight compared with birth weight in 62 twins who had ultrasound examinations less than seven days before delivery showed a significant correlation (r = 0.89, P less than .001) with a coefficient of variation of 12.4%. The identification of intrauterine growth retardation (IUGR) in twin pregnancies by ultrasound had a sensitivity of 62%, a specificity of 98%, and a predictive value of positive and negative test of 93% and 83%, respectively.     

Accurate ultrasonic estimation of fetal weight

The accuracy of eight ultrasonic fetal weight formulas were analyzed in 1099 fetuses who underwent real-time ultrasound examination within 72 hours prior to delivery. Shepard's formula was most consistently found to give the lowest systematic and random errors throughout all weight categories, though Deter's formula had an almost identical accuracy. The Shepard formula was further analyzed in respect to the effects of fetal sex and birthweight centile grouping on the accuracy of fetal weight estimation. The results indicated that fetal sex had no effect on the accuracy of fetal weight estimation, but that birthweight centile grouping did. The weights of small-for-gestational age infants were systematically overestimated, while the weights of large-for-gestational age infants were systematically underestimated.     

Sonographic diagnosis of intrauterine growth retardation using the postnatal ponderal index and the crown-heel length as standards of diagnosis

One hundred twenty-one patients underwent an ultrasound examination within 48 hours of delivery to assess prospectively the reliability of the diagnosis of intrauterine growth retardation. Sonographic parameters examined included the abdominal circumference, sonographic estimate of fetal weight, the head to abdominal circumference ratio, and the femur length to abdominal circumference ratio. The best obstetric estimate of gestational age was used. The diagnosis of growth retardation was based on the postnatal ponderal index, and or the birthweight and crown-heel length percentiles. Seventeen infants were growth retarded. Fifteen infants had a birthweight less than the 10th percentile, but only nine (60%) were either asymmetrically growth retarded (by their ponderal index) or symmetrically growth retarded (by virtue of a birthweight and length less than the 10th percentile). All sonographic parameters were better able to predict a birthweight below the 10th percentile for gestational age than growth retardation. An abdominal circumference less than the 2.5 percentile for gestational age had the highest sensitivity for growth retardation (88.0%) of the parameters studied. Only the abdominal circumference centile identified all infants with either symmetric growth retardation or asymmetric growth retardation associated with a birthweight below the 10th percentile. A sonographic estimate of fetal weight below the 10th percentile had the highest positive predictive value for growth retardation--38%. In contrast to the overall poor positive predictive values, the negative predictive values for all parameters studied exceeded 90%. Combining the abdominal circumference percentile with one of the three remaining techniques did not significantly improve diagnostic accuracy.(ABSTRACT TRUNCATED AT 250 WORDS)     

Estimation of fetal weight by ultrasound prior to 33 weeks gestation

The aim of this study was to develop an accurate formula for the ultrasonic prediction of fetal weight for infants < 33 weeks gestational age and < or = 1500 g birthweight. The subjects comprised live births free of lethal malformations or chromosomal anomalies, < 33 weeks gestational age and with birthweights +/- 1500 g born in the Royal Women's Hospital between January 1990 and March 1996. All subjects had accurate gestational age confirmed by ultrasound prior to 20 weeks gestation and ultrasound measurements within 72 hours of birth of biparietal diameter (BPD), femur length (FL) and abdominal circumference (AC). A formula with the highest explained variance was computed by linear regression analysis using the three fetal variables in various combinations from 54 infants born between January 1990 and December 1993. The optimal formula was: Log(10)birthweight = 0.714627 + 0.077362.AC + 0.058758.BPD + 0.287037.FL - 0.011274.AC.FL. The new formula was more accurate compared with existing formulae when tested in a separate cohort of 39 infants born between January 1994 and March 1996.     

Below median birth weight in appropriate-for-gestational-age preterm infants as a risk factor for bronchopulmonary dysplasia

AIMS: To assess the presence of chorioamnionitis and intrauterine growth as prenatal risk factors for broncho pulmonary dysplasia (BPD) in appropriate-for-gestational-age (AGA) infants of <28 weeks' gestation. METHODS: Gender, race, birth weight, gestational age, histology of the placenta, diagnosis of BPD at 36 weeks' gestation, postnatal dexamethasone treatment, and death were recorded in 150 preterm infants born at <28 weeks' gestation, and admitted between 1996 and 2001. RESULTS: In 122 AGA infants (mean gestational age: 26.18 weeks, mean birth weight: 837 g), BPD was associated with gestational age-related birth weights below the 50(th) centile. Intrauterine growth deceleration started between 25 and 26 weeks' gestation. Chorioamnionitis was not related to BPD. CONCLUSIONS: AGA infants of 26-28 weeks' gestation with birth weights below the median showed an increased risk of developing BPD.     

Is obstetric and neonatal outcome worse in fetuses who fail to reach their own growth potential?

OBJECTIVES: To determine the perinatal outcome of fetuses who had birthweights less than that expected from early third trimester ultrasound scanning. DESIGN: Retrospective estimation of centile fetal weight at early third trimester ultrasound scanning compared with actual centile birthweight corrected for gestational age, parity and sex. SETTING: Teaching Hospital Obstetric Unit, London. SUBJECTS: 197 unselected women with singleton cephalic pregnancies who were delivered at term in our unit between October 1989 and May 1990. MAIN OUTCOME MEASURES: CTG abnormality, need for fetal blood sampling in labour, meconium-staining of the amniotic fluid, mode of delivery, Apgar scores at 1 and 5 min, need for transfer of baby to neonatal unit, and need for neonatal intubation of the neonate at delivery. RESULTS: An actual birthweight greater than 5% less than the birthweight estimated from ultrasound scanning identified 44 babies (22%) with an increased risk of CTG abnormalities (chi 2 = 8.38, P less than 0.0025; Odds ratio (OR) = 2.54; 95% CI 1.36 to 4.78) and need for operative delivery (chi 2 = 5.81, P less than 0.0125; OR = 1.94; 95% CI 1.15 to 3.27), when compared with the remainder of the sample. Overall 14 (32%) of this group had birthweights above the 50th centile. A group of 44 babies selected as being the smallest for gestational age, without reference to growth pattern, had a similar excess morbidity. (All this group had birthweights below the 39th centile). CONCLUSIONS: This study supports the hypothesis that in-utero fetal growth pattern is as important for perinatal outcome as being small for gestational age per se.     

High maternal serum alpha-fetoprotein and low birthweight. A study concerning possible correlation between maternal weight, smoking, and serum alpha-fetoprotein and subsequent birthweight and gestational age

Maternal serum alpha-fetoprotein (AFP) levels between 15 and 19 weeks gestation were studied in relation to birthweight, gestational age, maternal weight, and daily cigarette consumption in 1739 pregnancies. All infants were born after the 28th week of gestation and all were without neural tube defects. Gestational age was estimated by early measurement of the fetal biparietal diameter. High maternal serum AFP, low maternal weight, and the number of cigarettes smoked per day were found to correlate with low birthweight, but not with gestational age. By testing the influence of the individual parameters on the subsequent birthweight, no significant correlation was found between the AFP levels and birthweight. Low birthweight was mainly a result of cigarette smoking and low maternal weight. Screening for AFP in the second trimester, therefore, seems to be of no value in predicting low birthweight when maternal weight is taken into consideration.     

A prospective comparison of clinical and ultrasonic methods of predicting normal and abnormal fetal growth

Charts of symphysial-fundal height (SFH) and ultrasound growth of fetal biparietal diameter (BPD) and abdominal circumference (FAC) were used simultaneously for the antenatal diagnosis of altered fetal growth in 100 patients. After delivery, infants were classified as small-for-gestational age (SGA), appropriate for gestational age (AGA) and large for gestational age (LGA) by birthweight and the postnatal diagnoses compared to antenatal diagnoses. The results indicate that although SFH is as good as ultrasound in predicting normal fetal growth, it is less sensitive than ultrasound for the diagnosis of SGA infants and even less so for macrosomia.It is concluded that SFH should be retained or instituted as a routine screening test for abnormal fetal growth.     

Controlled trial of ultrasound screening for light for gestational age (LGA) infants in late pregnancy

The study included 3311 pregnant women: 1570 in the screened group and 1741 in the unscreened group. In the screened group, ultrasound was offered routinely in the 32nd and 37th week of pregnancy, at which time the fetal biparietal diameter (BPD) and the abdominal mean diameter (AD) were measured. If, after the first ultrasound examination, the estimated weight was less than 85% of the expected mean birthweight, a finding of light for gestational age (LGA) was suspected and the ultrasound examination was repeated in the 34th week. In the screened group 6.5% of the women were at risk at the final ultrasound examination (the sensitivity was 38%) and the predictive values of abnormal and normal weight deviation were 60% and 93%, with a specificity of 97% and a relative risk of 9. Ultrasound was offered to the unscreened group only in cases of clinical concern (23% of the women). In the unscreened group 34% of the 158 LGA infants had ultrasound performed before delivery because of clinical concern. By including pregnancies induced before ultrasound could be performed, 45% of the LGA infants in the unscreened group were suspected before delivery. No significant difference between the rate of induction, instrumental deliveries and caesarean sections was found between the two groups. No benefit in terms of decreased incidence of infants with low Apgar score and acidosis was achieved.     

Intrauterine volume, fetal abdominal area and biparietal diameter measurements with ultrasound in the prediction of small-for-dates babies in a high-risk obstetric population.

Summary. . The value of fetal biparietal diameter and abdominal area, total intrauterine, intra-amniotic and placental volume measurements for predicting small-for-dates babies in a high-risk obstetric population was investigated in 130 women. A parallel planimetric area method was used to measure volume. The commonest risk factors were suspected intrauterine growth-retardation, hypertensive complications and previous poor obstetric history. The prevalence of birthweight at and below the 10th or 3rd centiles was 30 and 16% respectively. Fetal abdominal area and total intrauterine volume measurements had the highest and comparable sensitivity, specificity and positive predictive value in the detection of infants with birthweights of 10th and 3rd centiles. While these measurements are of use in consolidating the clinical diagnosis of small-for-dates fetuses (growth retardation), high false positive rates (10% and 16–17% for birthweights 10th centile, and 3rd centile respectively) make further discriminatory tests necessary for part of the population.     

Maternal smoking does not affect fetal size as measured in the mid-second trimester

BACKGROUND: Cigarette smoking during pregnancy is causally related to birthweight, but we do not know whether fetal growth restriction is a continuous process or, if not, at what stage of pregnancy it affects weight gain. MATERIAL AND METHODS: A random sample of para 1 and 2 mothers, drawn from the population of pregnant women in Bergen and Trondheim, Norway, and Uppsala, Sweden, were examined by a detailed questionnaire concerning smoking habits, menstrual history and pregnancy dating, and subjected to morphometric sonography of their fetuses in or around week 17. Of the 547 study participants, 31.9% were smokers. Gestational age was primarily determined by the last menstrual period [LMP], except in those with irregular cycles, and in 30 cases (6.6% of those with regular cycles) in whom the biparietal diameter [BPD]-determined age deviated >14 days from the LMP-based date. RESULTS: The analysis did not reveal any statistically significant differences between the fetuses of non-smokers, light smokers (0-9 cigarettes per day) and heavy (10+ cigarettes per day) smokers, regarding BPD, mean abdominal diameter [MAD] femur length [FL], and a 'body contour index': [BPD+FL]/MAD. CONCLUSION: Tobacco-induced fetal growth restriction probably begins after gestational week 17.     

Real-time ultrasound estimations of weight in fetuses of diabetic gravid women

To test the applicability of equations for fetal weight estimations in a group of fetuses suspected of being large for gestational age, real-time ultrasound measurements of fetal biparietal diameters and abdominal circumferences were obtained for 34 fetuses of diabetic mothers. In the first phase of the study the accuracy in the prediction of weight was assessed with use of two known equations. In the second phase, biparietal diameter, abdominal circumference, and actual birth weight data of the 34 study fetuses were used as independent variables to determine the best-fitting equation for relating estimated fetal weight (EFW) to biparietal diameter (BPD) and abdominal circumference (AC); this equation is log (EFW) = 0.02597 AC + 0.2161 BPD - 0.1999 (AC X BPD2)/1000 + 1.2659. The standard deviation of differences is 322.26 gm and multiple R = 0.781. In the final phase the reliability of this equation was compared to those of Thurnau and Shepard in 34 additional fetuses of diabetic gravid women. The data suggest that in these fetuses suspected of being large for gestational age the weight estimates calculated at or near term may be enhanced if predictive equations are formulated specifically from the data for such fetuses.     

Intra-uterine weight curves obtained by ultrasound

Using multiple regression analysis, a formula was evolved for estimating fetal weight in utero, based on fetal biparietal diameter (BPD), abdominal diameter (AD) (mean of two orthogonal readings), and femur length (FL), measured by ultrasound within 48 hours before delivery or legal abortion in a stratified sample of 89 pregnancies, approx. 10 in each 500-g weight class up to 5 000 g. Tested on 135 neonates of varying birth weights, the formula evolved, wt = BPD0.972 X AD1.743 X FL0.367 X 10(-2.647), neither under- nor over-estimated weight in any weight class, the error in estimates having a standard deviation of 7.1%, and maximum error being 18% of true weight. To establish an intrauterine growth curve, the formula was applied to 177 longitudinal measurements in 19 normal pregnancies; the estimated weight against gestational age (GA) curve so obtained best fitted a third-degree equation, wt = 1443.4 - 32.32 X GA + 0.203 X GA2 - 0.000215 X GA3 (r2 = 0.978), tallying closely with the birth weight curve obtained in the same population from 4743 pregnancies where gestational age had been assessed by ultrasound in early pregnancy. The present two growth curves, based on fetometry and on birth weight, differ from previous curves used almost universally by pediatricians.     

Divergence of estimated fetal weight and birth weight in singleton fetuses

Objective: To evaluate differences in distribution of estimated fetal weight (EFW) and birth weight (BW) of ongoing fetuses and neonates of the same gestational age.

Methods: Reference curves for EFW (Hadlock BPD-HC-AC-FL formula, N?=?1191) and BW (N?=?1036) in singleton pregnancies from 24⁺⁰ to 40⁺⁶ gestational weeks were calculated. Multiple pregnancies, fetuses with major or multiple abnormalities or syndromes and iatrogenic preterm deliveries due to preeclampsia or abnormal fetal Doppler were excluded. The standardized residuals for EFW and BW were calculated and compared.

Results: EFW and BW can be accurately described by quadratic equations (R²?=?0.944 and 0.807, respectively). The distribution of standardized residuals for BW using the EFW formula was negative from 28⁺⁰ to 35⁺⁶ weeks. The 50th and 5th centiles of BW were lower than those of EFW throughout prematurity, and they converged at approximately 38 gestational weeks. The 5th centile for BW was 30% lower than the 5th centile for EFW at 27 weeks, 27.5% lower at 30 weeks and 19.4% at 34 weeks.

Conclusions: Preterm infants have lower BW distribution compared to the expected EFW of ongoing pregnancies of the same gestational age, supporting the concept of hidden intrauterine morbidity for a proportion of these infants.     

Fetal age assessment based on ultrasound head biometry and the effect of maternal and fetal factors

BACKGROUND: Maternal height and weight have increased during the past 20 years, as has birthweight. The aim of the present study was to establish new reference charts for gestational age (GA) assessment using fetal biparietal diameter (BPD) and head circumference (HC), and to determine the effect of maternal and fetal factors on age assessment. METHODS: This was a prospective, cross-sectional study of 650 healthy women with regular menstrual periods and singleton uncomplicated pregnancies, recruited after written consent. BPD (outer-outer) and HC were measured at 10-24 weeks of gestation. We used regression analysis to construct mean curves and assess the effect of maternal and fetal factors on age assessment. RESULTS: BPD and HC were successfully measured in 642 participants. Using BPD and HC before 20 weeks, the new charts gave 3-8 days higher GA assessment than the charts presently in use, and <1 day difference compared to other recently established charts. Maternal age, multiparity, fetal gender, breech position and shape of fetal head affect GA estimation by 1-2 days when using BPD (p = 0.0001-0.02). Only maternal age and fetal gender affected GA estimation when using HC (相似文献   

Detection of small for gestational age fetuses by the combination of clinical risk factors and ultrasonography

Clinical risk factors of fetal growth retardation and targeted ultrasound examinations were combined to detect small for gestational age (SGA) fetuses below the 10th percentile weight for age in 1122 unselected singleton pregnancies, in which the true gestational age was confirmed by ultrasonography at 18 weeks. The prevalence of SGA infants was 6.0% in this population. A risk group of 236 (21%) mothers was referred for an ultrasound examination of fetal growth by the midwives of maternity welfare centers on the basis of low symphysis-fundal height or five other major maternal risk factors (pregnancy associated hypertension, loss of weight gain, a previous SGA infant, pre-pregnancy weight below 50 kg, any smoking during pregnancy). The sensitivity and positive predictive value of the clinical part of the study were 83.6 and 23.7%, respectively. Fetal growth was assessed by measuring both biparietal diameter (BPD) and transverse abdominal diameter. In the clinically selected risk group, 83.9% of the SGA fetuses could be detected by this method using a cutoff level of -1 standard deviation (SD). The two-step screening combining clinical and ultrasonographic methods in the detection of SGA fetuses in general population showed a sensitivity of 70.1%, a specificity of 95.5%, a positive predictive value of 49.5%, and a negative predictive value of 98.1%. After ultrasound examination, the definitive risk group for SGA was 8.5% of the total material of 1122.(ABSTRACT TRUNCATED AT 250 WORDS)