Value of fetal ponderal index in predicting growth retardation

Fetal ponderal indexes were calculated by ultrasound examination and compared with the neonatal ponderal indexes in 113 pregnancies. The relationship between the fetal and neonatal ponderal indexes throughout gestation is described. The fetal ponderal index also was evaluated as a predictor of intrauterine growth retardation (IUGR) and was found to have sensitivity and specificity of 76.9 and 82%, respectively. These data suggest that the fetal ponderal index could be used to rule out the diagnosis of IUGR with reasonable accuracy (negative predictive value 96.4%).     

Effectiveness of ultrasound determination of fetal abdominal circumference and fetal ponderal index in the diagnosis of asymmetrical growth retardation

A total of 310 unselected women attending an antenatal clinic was screened for growth retardation by ultrasound between 34 and 36 weeks gestation, by measuring the fetal abdominal circumference (AC) and femoral length (FL), from which the 'fetal ponderal index' (AC/FL) was calculated. Asymmetrical growth retardation in the newborn was assessed by Rohrer's ponderal index and the mid-arm/occipito-frontal circumference (MAC/OFC) ratio within 72 h of birth, a neonatal ponderal index or MAC/OFC ratio below the 10th centile being considered abnormal. The sensitivities of an AC below the 25th centile in identifying a birthweight, neonatal ponderal index or MAC/OFC ratio below the 10th centile were 86, 62 and 67% respectively, the specificities being 80, 78 and 76%. The sensitivities of a fetal ponderal index below the 25th centile in identifying a neonatal ponderal index or MAC/OFC ratio below the 10th centile were 52 and 47% respectively, the specificities being 77 and 77%. A possible reason for the poor performance of the fetal ponderal index is discussed.     

Effectiveness of ultrasound determination of fetal abdominal circumference and fetal ponderal index in the diagnosis of asymmetrical growth retardation

Summary. A total of 310 unselected women attending an antenatal clinic was screened for growth retardation by ultrasound between 34 and 36 weeks gestation, by measuring the fetal abdominal circumference (AC) and femoral length (FL), from which the 'fetal ponderal index' (AC/FL) was calculated. Asymmetrical growth retardation in the newborn was assessed by Rohrer's ponderal index and the mid-arm/ occipito-frontal circumference (MAC/OFC) ratio within 72 h of birth, a neonatal ponderal index or MAC/OFC ratio below the 10th centile being considered abnormal. The sensitivities of an AC below the 25th centile in identifying a birthweight, neonatal ponderal index or MAC/ OFC ratio below the 10th centile were 86, 62 and 67% respectively, the specificities being 80, 78 and 76%. The sensitivities of a fetal ponderal index below the 25th centile in identifying a neonatal ponderal index or MAC/OFC ratio below the 10th centile were 52 and 47% respectively, the specificities being 77 and 77%. A possible reason for the poor performance of the fetal ponderal index is discussed.     

The ponderal index in triplets: IV. Relationship with maternal height

The purpose of the study was to further evaluate the relationship between maternal height and neonatal ponderal index and length. A total of 774 triplet sets with matched maternal stature was available for analyses. We found a significant correlation between maternal height and infant length for both nulliparas (R2=0.70, p=0.04) and multiparas (R2=0.99, p=0.00005). The slopes of the regressions were different than zero, but the difference between the respective regressions was not significant (p=0.83). The analysis revealed a significant correlation between infant ponderal index and maternal stature for nulliparas (R2=0.68, p=0.04) but not for the multiparas (R2=0.08, p=0.6). The slope of the regression for nulliparas was different than zero, but that for the nulliparas was not. The difference between the respective regressions was significant (p=0.03). We conclude that taller mothers deliver longer infants, irrespective of parity, whereas the effect of maternal height on the ponderal index is parity-dependent.     

The ponderal index in triplets: III. Association with birth weight discordance

Our objective was to determine the association of the ponderal index with birth weight discordance in triplets. We analyzed data from triplets delivered at 28-37 weeks for birth weight discordance (>25% difference between the heaviest and lightest triplet). Three categories of discordance (low skew, symmetrical, and high skew) were classified according to the relative position of the middle triplet. Birth weights and the ponderal index (birth weight/[length]3) of all concordant and discordant triplet groups were compared. Of 752 triplet sets included, 184 (24.5%) were discordant. Total triplet birth weight was higher in the concordant compared to all discordant categories. As opposed to birth weight, where only the middle triplet differed according to discordance pattern, the ponderal index for the largest triplet was significantly higher in the low skew discordant group compared to the concordant and other discordant triplet groups. In contrast, the ponderal index for the smallest and middle triplets were similar among the discordant groups. We concluded that discordance in triplet pregnancies exhibits different patterns of mass (birth weight) versus size (ponderal index). Our findings suggest that it may be the size of largest triplet that determines the presence or absence or discordance in triplet gestations.     

The ponderal index in triplets: II. Gestational age-related patterns of neonatal weights and lengths

In order to evaluate the determinants of high and low ponderal indices in triplets, we analyzed prospectively collected data from a cohort of 2181 triplet births. Low and high neonatal ponderal indices (birth weight/[length]3) were defined as below or above 1 SD from the mean. The mean ponderal index was of 2.4 +/- 0.4. At 30-31 weeks, there were significantly more infants with a low ponderal index; after 33 weeks, more infants were born with a high index. Birth weights of infants with a high index were significantly higher throughout the entire range of gestational ages, whereas their lengths were significantly smaller. Both birth weights and infant length had significant correlations with gestational ages for infants with a low (R2=0.97 and R2=0.94, respectively) as well as with high ponderal indices (R2=0.95 and R2=0.94, respectively). The regression analyses suggest, however, different patterns for infants with low or high ponderal indices.     

The ponderal index in triplets: I. Relationship to small for gestational age neonates

The aim of the study was to examine the ponderal index in small for gestational age (SGA) triplets. Prospectively collected data from a cohort of triplets born at 28 to 37 weeks were analyzed. A low neonatal ponderal index (birth weight/[length]3) was defined as less than 1 SD below the mean (2.0), and SGA was considered as birth weight below the 10th percentile by triplet standards. We studied 2181 sets of triplets. Triplets delivered at < or = 33 weeks have a lower mean ponderal index compared with those delivered at > 33 weeks. About 70% of SGA triplets do not have a low ponderal index, whereas 79.2% of infants with a low ponderal index are not SGA by triplet standards. Both the frequency of a low ponderal index and the frequency of infants with a low ponderal index who are not SGA decrease with increasing gestational age. We conclude that the majority of triplets with a low ponderal index might not be considered growth restricted, supporting the concept that reduced fetal weight of triplets is more likely a physiological rather than a pathological phenomenon.     

Head circumference/abdominal circumference ratio, ponderal index and fetal malnutrition. Should head circumference/abdominal circumference ratio be abandoned?

Head circumference/abdominal circumference (HC/AC) ratios of the fetus are accepted as a means of distinguishing different patterns of growth retardation with a high ratio implying malnutrition of the fetus. Ponderal index (birthweight/length3) is used by paediatricians as a measure of neonatal wasting and would therefore be expected to correlate with HC/AC ratios at delivery. Anthropometric data on 999 newborn infants have been collected and analyzed by multiple regression. The results show a poor correlation between ponderal index and HC/AC ratio, worse than that between ponderal index and AC alone. The use of HC/AC ratios antenatally to identify subgroups of intrauterine malnutrition should be abandoned. The prediction of intrauterine malnutrition by weight/length ratios should be investigated further.     

Head circumference/abdominal circumference ratio, ponderal index and fetal malnutrition. Should head circumference/abdominal circumference ratio be abandoned?

Summary. Head circumference/abdominal circumference (HC/AC) ratios of the fetus are accepted as a means of distinguishing different patterns of growth retardation with a high ratio implying malnutrition of the fetus. Ponderal index (birthweight/length³) is used by paediatricians as a measure of neonatal wasting and would therefore be expected to correlate with HC/AC ratios at delivery. Anthropometric data on 999 newborn infants have been collected and analyzed by multiple regression. The results show a poor correlation between ponderal index and HC/AC ratio, worse than that between ponderal index and AC alone. The use of HC/AC ratios antenatally to identify subgroups of intrauterine malnutrition should be abandoned. The prediction of intrauterine malnutrition by weight/length ratios should be investigated further.     

Maternal and fetal leptin and ghrelin levels: relationship with fetal growth

Purpose  

In our study, we investigated the influence of plasma levels ghrelin, leptin and other metabolic hormones (ILGF-1 and ILGF-2) in pregnants in regulating fetal body weight and mode of delivery.     

Fetal ponderal index as an instrument for further classification of intra-uterine growth retardation.

Perinatal morbidity and mortality are still high in cases of intra-uterine growth retardation. Present screening methods select large risk groups and have a low positive predictive value. Instruments which could be used as indicators for those cases within the risk group needing close fetal monitoring would be valuable. The aim of this prospective study was to evaluate fetal ponderal index with respect to signs of fetal distress and neonatal outcome. By means of a risk scoring system, 73 pregnancies with increased risks of intra-uterine growth retardation were compared with 61 controls. By means of ultrasound, fetal weight was estimated and the fetal femur measured. The fetal ponderal index was calculated by dividing the estimated fetal weight in grams by the third power of the femur length. In the control group, 5/61 showed signs of distress and in the risk group, 43/73. The mean fetal ponderal index of the controls was 8.60 (SD 0.84) and in the risk group 7.72. The groups were compared with each other with respect to signs of distress. The fetuses showing signs of distress had a mean FePI of 7.45 (p less than 0.001). Those (30/73) in the risk group not showing signs of fetal distress had a mean value of 8.14 and differed significantly (p less than 0.001) from the distress group. Fetal ponderal index would seem to be a valuable adjunct for the differentiation of the more susceptible fetuses in an intra-uterine growth retardation risk group.     

Macrosomia prediction using ultrasound fetal abdominal circumference of 35 centimeters or more

OBJECTIVE: To determine if birth weights greater than 4000 g can be predicted by ultrasound measurements of abdominal circumferences. METHODS: In 1996, 254 newborns delivered at Tampa General Hospital weighed at least 4000 g, 84 of whom had ultrasound examinations within 2 weeks of delivery. Those were compared with 84 neonates with recent ultrasounds who weighed less than 4000 g. Data were abstracted retrospectively from maternal medical records. RESULTS: The best linear predictor of birth weight was ultrasound measurement of abdominal circumference (AC), which had a correlation coefficient of 0.95. An AC measurement of 35 cm or more predicted 93% of macrosomic infants. Among 177 macrosomic infants born vaginally, 23 (13%) had shoulder dystocia. In that group, induction of labor was associated with a greater than three-fold increase in risk of shoulder dystocia (odds ratio [OR] 3.4, 95% confidence interval [CI] 1.4, 8.2; P < .01). Labor augmentation was not associated with increased risk of shoulder dystocia. CONCLUSION: Abdominal circumference measurements were useful in screening for suspected macrosomia. An AC measurement of 35 cm or more identified more than 90% of macrosomic infants who were at risk for shoulder dystocia. Induction of labor in macrosomic patients increased the risk of shoulder dystocia.     

Chronic villitis of unknown aetiology and intrauterine growth-retarded infants of normal and low ponderal index

Placentae from 211 term pregnancies were studied. The placentae were divided into three groups: group I, 57 placentae from neonates with birthweight over the 25th centile of the normal birthweight curve; group II, 49 placentae from neonates whose birthweight fell between the 10th and 25th centiles of this curve, and group III, 105 placentae from neonates whose birthweights were below the 10th centile of the curve. Each of the studied groups were divided into two subgroups, one comprising those infants with a normal Ponderal Index (PI) and the other comprising those with a low PI. A higher incidence of chronic villitis and of inflamed villi was observed as the average birthweight decreased in cases with normal PI as well as in cases with low PI, the highest incidence being found in placentae from infants with harmonic intrauterine growth retardation (normal PI). The same was observed with respect to the presence of maternal vascular lesions in all groups studied. It is suggested that an infant's birthweight and crown-heel length may be affected as a consequence of the extension and severity of the placental lesions and the timing of their appearance in gestation.     

Stereological study of the placentae in intrauterine growth retardation with different ponderal index]

10 placentae each from the cases of IUGR with normal ponderal index (NPI) and low ponderal index (LPI) and 10 from normal pregnancy as control were analysed quantitatively with stereological principles. This study showed the placental weight, volume, surface area of villi and villous fetal capillary in IUGR were significantly reduced than that in control group. The percentage ratio of the fetal capillary volume was increased significantly in IUGR group but the ratio of vasculo-syncytial membrane/villous fetal capillary decreased. It suggested that compensation to anoxemia in placenta of IUGR was incomplete. The data also found that all the parameters in NPI group were decreased significantly than that in LPI group, which implied NPI group had a more severe growth deficiency of the placental functional structure. When placental growth deficiency occurs in the first or second trimester, both the fetal length and weight will be severely affected.     

Fetal overgrowth in pregnancies complicated by diabetes: development of a clinical prediction index

Purpose

To develop an index to predict fetal overgrowth in pregnancies complicated by diabetes.

Methods

Data were derived from a cohort of 275 women with singleton gestations in a collaborative diabetes in pregnancy program. Regression analysis incorporated clinical factors available in the first 20–30 weeks of pregnancy that were assigned beta-coefficient-based weights, the sum of which yielded a fetal overgrowth index (composite score).

Results

Fifty-one (18.5%) pregnancies were complicated by fetal overgrowth. The derived index included five clinical factors: age?≤?30, history of macrosomia, excessive gestational weight gain, enlarged fetal abdominal circumference, and fasting hyperglycemia. Area under the curve (AUC) for the index is 0.88 [95% confidence interval (CI) 0.82–0.92]. Cut-points were selected to identify “high-risk” and “low-risk” ranges (≥?8 and?≤?3) that have positive and negative predictive values of 84% (95% CI 70–98%) and 95% (95% CI 92–98%), respectively. The majority of women in our cohort (n?=?182, 66%) had a “low-risk” index while 9% (n?=?25) had a “high-risk” index. Sub-analyses of nulliparous women and women with gestational and pre-gestational diabetes revealed that the overgrowth index was equally or more predictive when applied separately to each of these groups.

Conclusion

This fetal overgrowth index that incorporates five clinical factors provides a means of predicting fetal overgrowth and thereby serves as a tool for targeting the allocation of healthcare resources and treatment individualization.