Screening for intrauterine growth retardation using ratio of mid-arm circumference to occipitofrontal circumference

Comparative Assessment of Fetal Malnutrition by Anthropometry and CAN Score

OBJECTIVES

Fetal malnutrition (FM) implies soft tissue wasting at birth with significant postnatal consequences and morbidity, and is identified by clinical assessment (CAN score) and anthropometry. No previous studies have been done to study all these parameters and evolve a screening method. The aim of this study was identifying the incidence of FM using CAN score and compare the nutritional assessment with anthropometry and evolve a screening tool for rapid assessment of FM.

METHODS

Prospective study in Government district maternity hospital. 300 term newborns were assessed by CAN score and anthropometry recorded. The newborns were classified as per weight for age. Ponderal index (PI), Body mass index (BMI) and midarm circumference/head circumference ratio (MAC/HC) calculated and compared to CAN Score for accuracy in identifying FM.

FINDINGS

Incidence of FM was 24%. Newborns identified malnourished by PI, BMI, MAC/HC were evaluated by CAN score and significant number of them (31/78 in PI, 60/121 in BMI, 51/81 in MAC/HC) were found well nourished. Similarly those recognized as normal by PI, BMI, MAC/HC were malnourished by CAN score(25/222 in PI, 11/179 in BMI, 42/219 in MAC/HC) with statistical significance(0.0001). BMI had the highest sensitivity and 11 neonates with normal BMI had low CAN score ann 9 of them had normal PI also making a combination of BMI and PI a good indicator of normal nutrition.

CONCLUSION

FM is best identified by CAN Score. BMI is the best screening tool for malnutrition and when coupled with PI will identify most normally nourished newborns.

Assessing the value of customized birth weight percentiles

Customized birth weight percentiles are weight-for-gestational-age percentiles that account for the influence of maternal characteristics on fetal growth. Although intuitively appealing, the incremental value they provide in the identification of intrauterine growth restriction (IUGR) over conventional birth weight percentiles is controversial. The objective of this study was to assess the value of customized birth weight percentiles in a simulated cohort of 100,000 infants aged 37 weeks whose IUGR status was known. A cohort of infants with a range of healthy birth weights was first simulated on the basis of the distributions of maternal/fetal characteristics observed in births at the Royal Victoria Hospital in Montreal, Canada, between 2000 and 2006. The occurrence of IUGR was re-created by reducing the observed birth weights of a small percentage of these infants. The value of customized percentiles was assessed by calculating true and false positive rates. Customizing birth weight percentiles for maternal characteristics added very little information to the identification of IUGR beyond that obtained from conventional weight-for-gestational-age percentiles (true positive rates of 61.8% and 61.1%, respectively, and false positive rates of 7.9% and 8.5%, respectively). For the process of customization to be worthwhile, maternal characteristics in the customization model were shown through simulation to require an unrealistically strong association with birth weight.

Fractional limb volume--a soft tissue parameter of fetal body composition: validation, technical considerations and normal ranges during pregnancy

OBJECTIVES

The main goals were to provide normal reference ranges for fractional limb volume as a new index of generalized fetal nutritional status, to evaluate the reproducibility of fractional fetal limb volume measurements during the second and third trimesters of pregnancy, and to demonstrate technical considerations for this technique.

METHODS

This was a prospective, cross-sectional study of gravid women during mid to late pregnancy. Fractional limb volumes were based on either 50% of humeral or femoral diaphysis length. Each partial volume was subdivided into five equidistant slices that were centered along the mid-arm or mid-thigh. Slices were traced manually to obtain fractional arm (AVol) or fractional thigh (TVol) volume. Reproducibility studies were performed, using Bland-Altman plots, to assess blinded interobserver and intraobserver measurement bias and agreement. Selected images were chosen to demonstrate technical factors for the acquisition and analysis of these parameters. Reference charts were established to describe normal ranges for AVol and TVol.

RESULTS

Three hundred and eighty-seven subjects were scanned to include 380 AVol (range, 1.1-68.3 mL) and 378 TVol (range 2.0-163.2 mL) measurements between 18.0 and 42.1 weeks' menstrual age. No gender differences were found in these soft tissue measurements (AVol, P = 0.90; TVol, P = 0.91; Mann-Whitney test). Intraobserver mean bias +/- SD and 95% limits of agreement (LOA) for fractional limb volumes were: 2.2 +/- 4.2% (95% LOA, - 6.0 to 10.5%) for AVol and 2.0 +/- 4.2% (95% LOA, - 6.3 to 10.3%) for TVol. Interobserver bias and agreement were - 1.9 +/- 4.9% (95% LOA, - 11.6 to 7.8%) for AVol and - 2.0 +/- 5.4% (95% LOA, - 12.5 to 8.6%) for TVol. Technical factors were related to image optimization, transducer pressure, fetal movement, soft tissue compression and amniotic fluid volume.

CONCLUSIONS

Fractional limb volume assessment may improve the detection and monitoring of malnourished fetuses because this soft tissue parameter can be obtained quickly and reproducibly during mid to late pregnancy. Careful attention should be placed on technical factors that can potentially affect optimal acquisition and analysis of these volume measurements.

Customized versus population-based birth weight standards for identifying growth restricted infants: a French multicenter study

OBJECTIVE

This study was undertaken to describe the characteristics of pregnancies according to a customized definition of fetal growth restriction and to determine the association between customized standards and adverse pregnancy outcomes.

STUDY DESIGN

Two definitions of growth restriction, a population and a customized standard, were applied to 56,606 births in 5 tertiary maternity hospitals in France from 1997 to 2002. The customized definition was adjusted for maternal height and weight, parity, fetal gender, and gestational age. Odds ratios and 95% CIs for neonatal morbidity and mortality were calculated to compare small for gestational age and non-small for gestational age births.

RESULTS

By using customized standards, 2.7% of births were reclassified as small for gestational age. These births were to taller, heavier, multiparous women. Compared with non-small for gestational age births, these newly detected small-for-gestational-age newborn infants showed an increased risk of stillbirth (odds ratio = 4.52, 95% CI 2.47-8.14) and perinatal death (odds ratio = 2.60, 95% CI 1.62-4.15). These infants were also more likely to be born to women with hypertensive disease in pregnancy (7.0%) versus those reclassified as non-small for gestational age (2.3%) and those non-small for gestational age by both standards (5.5%).

CONCLUSION

These findings highlight the interest of using customized birth weight standard adjusted for maternal and neonatal characteristics to identify fetuses at risk, particularly among apparently normal fetuses. Individual growth norms should be used to define small for gestational age.

Mid-arm circumference and mid-arm/head circumference ratio in term newborns

CONTEXT

Mid-arm circumference of the newborn is strongly associated with birth weight and is a very good indicator of low and insufficient birth weight. However, there are few Brazilian studies on the relationship between mid-arm and head circumferences and, thus, this does not form part of the routine evaluation for newborns.

OBJECTIVES

To establish the mid-arm circumference and mid-arm/head circumference ratio in a population of term newborns.

TYPE OF STUDY

Cross-sectional study carried out between June 1997 and August 1999.

SETTING

Hospital Maternidade Leonor Mendes de Barros, São Paulo.

PARTICIPANTS

Term newborns (66 males and 65 females) of appropriate growth for gestational age, whose mothers were healthy, were included in the study.

MAIN MEASUREMENTS

Arm circumference, arm circumference/head circumference ratio, birth weight and gestational age were measured within 48 hours of birth. Data were considered significant when p < 0.01.

RESULTS

The mean values for the mid-arm circumference were 10.76 cm (standard deviation, SD = 0.68) for females and 10.76 (SD = 0.81) for males. The mean value for the mid-arm/head circumference ratio was 0.31 (SD = 0.02) for both sexes. Mid-arm circumference values were significantly related to birth weight and gestational age, whereas mid-arm/head circumference ratio was related only to birth weight.

CONCLUSIONS

Mid-arm circumference and mid-arm/head circumference ratio values were established for the studied population. It was possible to obtain curves for both mid-arm circumference and mid-arm/head circumference ratio in relation to birth weight. However, for mid-arm circumference, it was only possible to obtain curves in relation to gestational age. The use of the regression curves did not seem powerful enough to predict the mid-arm circumference and mid-arm/head circumference ratio in this population of term newborns. There were no gender differences for either of the measurements studied.

Relationship between customised birthweight centiles and neonatal anthropometric features of growth restriction

OBJECTIVE

To determine the relationship between customised birthweight centiles (adjusted for maternal and fetal physiological variables) and neonatal anthropometric features of intrauterine growth restriction (IUGR).

DESIGN

Observational study.

POPULATION

Two-hundred and seventy women with low risk pregnancies participating in a cohort study of serial ultrasound biometry.

METHODS

Customised birthweight centiles were calculated following adjustment for maternal weight, height and ethnic origin, gestational age at delivery, birth order, and sex of the infant. Three separate neonatal anthropometric measures were used to define IUGR: subscapular or triceps skinfold thickness <10th centile; ponderal index <25th centile; and mid-arm circumference to occipito-frontal circumference ratio (MAC/OFC) <- 1 standard deviation (SD). Relationship of the centiles to these outcomes was evaluated using likelihood ratios (LR) and kappa statistic. These approaches allowed us to examine the strength of the association: an LR of 5-10 would be expected to generate moderate changes in the pre-test probability of IUGR, whereas a kappa value of 0.2-0.4 would reflect fair agreement between customised birthweight centiles and neonatal anthropometric measures.

RESULTS

Customised birthweight centile of 10 or less had the following LR values for the various anthropometric criteria for IUGR: 5.1 (95% CI 3-8.5) for low skinfold thickness; 4.3 (95% CI 2.5-7.1) for low ponderal index; and 3.9 (95% CI 2-6.6) for low MAC/OFC ratio. The kappa values were: 0.4 (95% CI 0.26-0.51) for low skinfold thickness; 0.33 (95% CI 0.21-0.46) for low ponderal index; and 0.13 (95% CI 0-0.26) for low MAC/OFC ratio.

CONCLUSION

In a low risk population, customised birthweight centiles can only be moderately useful in the identification of neonates with low skinfold thickness and low ponderal index.

Using unconditional and conditional standard deviation scores of fetal abdominal area measurements in the prediction of intrauterine growth restriction

OBJECTIVE

To compare the performance of unconditional and conditional standard deviation scores (Z scores) of fetal abdominal area (FAA) measurements in the antenatal identification of infants born with anthropometric features of intrauterine growth restriction.

METHODS

A prospective observational study, involving 274 low-risk women participating in a longitudinal study of serial ultrasound in pregnancy. Conditional Z scores were established for the last FAA prior to delivery with reference to measurements made both 28 and 56 days previously. Unconditional Z scores (size) were calculated from the last FAA measurement prior to delivery. Receiver-operator characteristics curves were employed to determine an optimal cut-off point for Z scores to predict intrauterine malnourishment. The main outcome measures were: likelihood ratios (LR) for conditional and unconditional Z scores of FAA in the prediction of infants with skinfold thickness < 10th percentile; ponderal index < 25th percentile or mid-arm circumference to occipitofrontal circumference ratio (MAC/OFC) of < -1 SD. An LR of > 10 generates significant changes in the pretest probability of growth restriction, whereas an LR of 5-10 generates only moderate changes.

RESULTS

Conditional Z scores with 28- and 56-day separations predicted growth restriction with LR 7.5 (95% confidence interval [CI], 3.7-14.7) and 4.8 (95% CI, 2.8-7.8) for ponderal index but did not usefully predict skinfold thickness or MAC/OFC. Unconditional Z scores did not usefully predict any of the parameters of growth restriction.

CONCLUSIONS

Quantifying third trimester fetal growth by means of FAA conditional Z scores is moderately useful in predicting infants with a low ponderal index and is superior to unconditional FAA Z scores in late pregnancy.

Influence of long-chain polyunsaturated fatty acids on infant cognitive function

Long-chain polyunsaturated fatty acids (LCPUFA) are important for normal visual and cortical development. In a previous study of the effects of LCPUFA on cognitive function of term infants at the age of 3 mon, we indicated that infants with evidence of reduced growth parameters at birth and impaired attention control as manifested by a late peak fixation during infant habituation assessment may benefit from LCPUFA supplementation. The aim of this prospective study was to determine whether LCPUFA supplementation and late peak fixation are related to means-end problem-solving ability in these same infants at the age of 9 mon. Term infants (58) were randomized to one of two formulas containing either LCPUFA or no LCPUFA and completed 4 mon of feeding with their formula. Cognitive function was assessed at 3 mon of age by measures of infant habituation. Infants (20 LCPUFA and 20 no-LCPUFA) completed the problem-solving assessment at 9 mon. The no-LCPUFA group had lower scores on both measures of intention and number of solutions, but neither of these differences was significant. Analysis of covariance for the effects of group and peak fixation, covaried with gestation and birth weight, showed that the number of solutions was significantly reduced in the late peak-fixation infants receiving no LCPUFA (P<0.02). Intention scores tended to be reduced in this group (P<0.06). The late peak-fixation infants who received LCPUFA had solution and intention scores similar to early peak-fixation infants receiving LCPUFA or no LCPUFA. These findings suggest that in term infants who have reduced growth parameters at birth and who show evidence of impaired attention control, information processing and problem-solving ability in infancy may be enhanced by LCPUFA supplementation.

Fetal growth velocity in the prediction of intrauterine growth retardation in a low risk population

OBJECTIVE

To determine whether fetal growth velocity derived from two antenatal ultrasound measurements in the third trimester, 28 days apart, can identify infants born with anthropometric features of intrauterine growth retardation.

DESIGN

Prospective observational study.

SETTING

Department of obstetric ultrasound, Ninewells Hospital, Dundee.

SUBJECTS

Two hundred and seventy four low risk women participating in a longitudinal study of serial fortnightly ultrasound in pregnancy.

METHODS

Growth velocities of the fetal abdominal area and bi-parietal diameter were calculated from the third from last and last measurements prior to delivery. Receiver Operator Characteristics curves were employed to determine an optimal cutoff point for velocity to predict intrauterine malnourishment.

MAIN OUTCOME MEASURES

Likelihood ratios for fetal abdominal area and bi-parietal diameter growth velocity in the prediction of growth retarded infants with skinfold thickness < 10th centile; ponderal index < 25th centile, or mid-arm circumference to occipito-frontal circumference ratio (MAC:OFC ratio) of less than -1 SD. A likelihood ratio of > 10 generates significant changes in the pre-test probability of growth retardation, whereas a likelihood ratio of 5 to 10 generates only moderate changes.

RESULTS

Fetal abdominal area velocity predicted growth retardation with likelihood ratio 10.4 (95% CI 3.9 to 26) for skinfold thickness; likelihood ratio 9.5 (95% CI 4.6 to 19) for ponderal index; a likelihood ratio 4.7 (2.3 to 8.4) for MAC:OFC. Bi-parietal diameter velocity predicted growth retardation with likelihood ratio 6.5 (95% CI 1.9 to 20) for skinfold thickness but did not predict low ponderal index or MAC:OFC ratio.

CONCLUSIONS

Fetal abdominal area velocity is useful in identifying infants with reduced skinfold thickness or low ponderal index. Prospective evaluation of serial ultrasound and velocity calculation in a selected population at increased risk of growth failure and a clearer understanding of the relative significance of the different neonatal anthropometric measures of impaired growth achievement is necessary before the estimation of growth velocity can be recommended in clinical practice.

The relationship of ponderal index and other measurements to birthweight in preterm neonates

The objective was to determine the relationship between birthweight and anthropometric indices (PI and MAC/ OFC) in preterm infants. A group of 163 singleton preterm neonates born at 24-36 weeks were examined. Measurements were made of crown-heel length, midarm circumference, and occipito-frontal circumference. Birthweights were calculated as multiples of the mean (MoMs) for a given stage of gestation. There was a highly significant correlation between gestational age and MAC/OFC (p < 0.0001) but none with ponderal index. There was a significant correlation between weight expressed as multiples of the mean and both ponderal index (p < 0.008) and MAC/OFC (p < 0.0001). This relationship between birthweight and anthropometric indices suggests that measurement of the ponderal index does not provide a useful index of intrauterine nutrition.

Chest circumference as an indicator of intrauterine growth retardation

Three hundred and fifty six intrauterine growth retarded (IUGR) and 356 appropriate birth weight (ABW) babies were studied for a range of different anthropometric measurements. Birth weights was highly correlated with chest circumference (r = 0.64, P < 0.001; r = 0.76, P < 0.001), length (r = 0.71, P < 0.001; r = 0.68, P < 0.001), and head circumference (r = 0.49, P < 0.001; r = 0.53, P < 0.001) either in IUGR and ABW babies, respectively. There were weak statistically significant correlations between birth weight and mid-upper arm circumference (MUAC) (r = 0.65, P < 0.001; r = 0.15, P < 0.001), MUAC/head circumference (r = 0.43, P < 0.001; r = 0.13, P < 0.001), triceps skinfold thickness (r = 0.31, P < 0.001; r = 0.14, P < 0.001), and ponderal index (r = 0.23, P < 0.001, r = 0.33, P < 0.001) in IUGR and ABW babies. All anthropometric measurements had a statistically significant sensitivity and specificity for identifying intrauterine growth retardation (IUGR). However, chest circumference < or = 29.0 cm; length < or = 47.5 cm; and head circumference < or = 33.0 cm has the highest sensitivity, specificity and predictive power. Chest circumference seems to be the easiest, cheapest and most reliable anthropometric measurement to assess IUGR.

Nutrition and growth in patients with chronic liver disease

Protein energy malnutrition leading to growth failure is an inevitable consequence of chronic liver disease in childhood. Although the precise pathophysiology is not understood considerable progress has been made in understanding the mechanisms of fat malabsorption and protein turnover in liver disease. There are many difficulties with the correct assessment of nutritional parameters in children with liver disease related to their abnormal body composition and energy expenditure and care needs to be taken with the interpretation of results. The effects of malnutrition secondary to chronic liver disease are varied and include fat soluble vitamin deficiencies, generalised growth failure, impairment of gastrointestinal function, immunosuppression and hypotonia. It is now recognised that malnutrition is an important risk factor for liver transplantation and increases both mortality and morbidity. Strategies to prevent or reverse malnutrition are now established and include the use of specific infant formulas based on low salt protein and an increased concentration of medium train triglyceride (50-70%). Careful nutritional support in association with generous fat soluble vitamin supplementation may produce dramatic improvement in catch up weight gain but for those children in whom growth failure persists, the only management is liver transplantation.

Neonatal morphometric indices of fetal growth: analysis of observer variability

Measurements of triceps and subscapular skinfold thickness, mid-arm circumference (MAC), head circumference (HC) and crown-heel length were performed by two observers in 30 healthy neonates. Intra-observer standard deviation for all measurements, calculated using one-way analysis of variance, was small and similar for each observer. Inter-observer variability was assessed using limits of agreement. There were small, systematic, differences between observers for measurements of triceps skinfold thickness and crown-heel length, and for calculated ponderal index (PI). When related to respective published reference ranges, the 95% prediction intervals for subscapular (-0.51, 0.68 mm) and triceps (-0.65, 0.29 mm) skinfold thicknesses were less than those for the MAC/HC ratio (-2.1, 1.9) and PI (-0.23, 0.28). The results indicate that skinfold thickness measurements are a more robust measure and, therefore, may be of greater value in the assessment of neonates with suspected fetal growth retardation.

Evidence of growth retardation in neonates of apparently normal weight

The aim of this study was to examine the relationship of ponderal index (PI) and the ratio of mid-arm circumference to occipito-frontal circumference (MAC/OFC) to the delivered weight of the child. Measurements were made on 160 singleton neonates with birthweight greater than 2500 g and delivery at 37 weeks or more. Surprisingly, there was a highly significant correlation between PI and birthweight and MAC/OFC and birthweight. We conclude that: (1) values of PI must be evaluated in relation to birthweight, and not against a single absolute standard for the whole normal population; (2) measurement of PI and MAC/OFC may reveal a group of growth-retarded infants amongst infants of apparently 'normal' birthweight; and (3) this group of infants might be a target for the extra care normally accorded to the low birthweight infant.

Anthropometric measurements in a newborn population in west Africa: a reliable and simple tool for the identification of infants at risk for early postnatal morbidity

The predictive value of anthropometric measurements in the identification of infants at risk for early postnatal morbidity was assessed in a cohort of 490 neonates born in Yaoundé, Cameroon. Mid-arm circumference (MAC), head circumference, weight, and length were measured within 6 hours of birth, and the gestational age, individual MAC/head circumference ratio, and individual ponderal index were calculated. A detailed questionnaire on gestational medical history was also obtained from the mothers. All infants were then closely monitored during the first 72 hours after delivery for the appearance of symptoms requiring medical intervention and treated accordingly. Low birth weight (LBW) was observed in 37.75%, prematurity in 25.5%, and small size for gestational age in 14.1% of the neonates. Gestational medical problems were reported by 44.3% of the mothers; malaria was the most frequent. Early postnatal morbidity was observed in 26% of the infants; infection (53%), respiratory distress (26%), hypoglycemia (26%), and convulsions (11.7%) accounted for most of the problems. The MAC correlated best of all variables with birth weight (r = 0.91); a value of less than or equal to 9.5 cm had a 93% sensitivity and a 90.5% specificity in the prediction of LBW. An MAC cutoff value of less than or equal to 9.5 cm was also the best of all variables in the prediction of early postnatal morbidity, and 85.2% sensitivity and 74.3% specificity were achieved. We conclude that in developing countries, where scales are not always available and the overburdened maternity wards cannot allow for medical surveillance of every infant, the MAC can be used in the estimation of birth weight. Moreover, an appropriately calculated cutoff value of MAC may serve as a reliable indicator of LBW and of infants at risk for early postnatal morbidity.

Standard curves for mid arm circumference and mid-arm/head circumference ratio in newborns

One Thousand singleton neonates, between 28 and 44 weeks of estimated gestational age (EGA) were measured within 48 hours of their birth for upper mid-arm circumference (MAC), head circumference (HC) and birth weight (BW). Regression analysis was used to draw standard curves for MAC versus EGA and mid-arm circumference/head circumference ratio (MAC/HC) versus EGA. Correlation coefficients were 0.961 for MAC versus EGA and 0.889 for MAC/HC versus EGA (p less than 0.001). MAC, MAC/HC and HC were also highly correlated with birth weight (p less than 0.001). These standard curves make available a discriminating method for evaluation of intra-uterine growth and a non-invasive technique for following somatic protein status in growing preterm infants.

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.

The ratio of mid-arm circumference to occipital frontal circumference in Chinese babies: a marker of late gestation growth retardation

The ratio of mid-arm circumference to occipital frontal circumference (MAC/OFC), an index of late gestation growth retardation, was determined in 175 healthy newborn term Chinese babies. The ratio of 0.31 (S.D., 0.02) was significantly higher than in recent data published for Asian, White and Black neonates: whether this is due to differences in measuring techniques or better intra-uterine nutrition remains to be seen. As an initial test of its potential usefulness this ratio was determined in 12 term Chinese babies who showed clinical signs of undernutrition. All but one had a ratio 2S.D. or more below the mean. The MAC/OFC ratio, with its ease of measurement, simplicity and cheapness, is a useful addition to existing methods for assessing late gestation nutritional status.

AIDS in an infant causing severe failure to thrive

A nine-month-old female Jamaican infant presented with a history of severe failure to thrive, recurrent pneumonia and developmental delay. She was found to have hepatosplenomegaly, generalised lymphadenopathy and hypotonia. Investigations revealed polyclonal hypergammaglobulinaemia, cytomegalovirus in her urine, and patchy lung infiltrates on her chest radiographs. Three separate tests were positive for human immunodeficiency virus in both the infant and her mother, suggesting vertical transmission, and confirming AIDS as the cause of the severe failure to thrive.