Growth patterns of the humeral and femur length in a multiethnic population

Humeral Length versus Femur Length for Estimating Fetal Age in the Third Trimester Using Ultrasound among Saudi Fetuses

Background

Ethnicity can influence organ measurements, so each ethnicity should provide normal references. The study was conducted to measure the normal ranges of humeral and femoral diaphysis lengths, to compare them during the third trimester of pregnancy in the Saudi population, and to identify their role in estimating fetal age.

Methods

This cross-sectional study was conducted among 60 normal singleton pregnant females in the third trimester. The fetal humeral length (HL) and femur length (FL) were taken during ultrasound scanning for follow-up. The IBM Statistical Package for the Social Sciences Version 23 was used to summarize the data and to compare both the lengths with the last menstrual period (LMP) using Pearson's correlation. The comparison was considered statistically significant if P < 0.05.

Results

The mean humeral and femoral diaphysis lengths ± standard deviations were 4.84 ± 1 cm and 5.54 ± 1.2 cm, respectively. A positive linear correlation was present between the length and LMP. The correlation of HL with LMP (r = 0.828) was higher than that of FL with LMP (r = 0.770). HL and FL were correlated. They showed a Pearson's coefficient of 0.941. The study revealed that gender does not affect fetal HL and FL.

Conclusion

Normal reference ranges for femur and humeral diaphysis lengths during the third trimester were provided. The humerus can be used to assess fetal age. Humerus and femur were correlated to each other among Saudi fetuses. Another study with a larger sample size is recommended.

Safe zone for lateral pin placement for external fixation of the distal humerus

External fixation is a common, efficient technique used for humeral shaft stabilization and elbow fractures. There are reports of radial nerve injuries associated with this procedure. In this study, we investigated the course and variability of the radial nerve along the lateral humerus in relation to the elbow joint to determine a relatively safe zone for lateral pin placement in external fixation. Twenty upper extremities from 10 cadavers were studied. The nerve branches and course of the radial nerve along the lateral humerus were carefully dissected. Straight lines (a, b, and c) were made connecting three landmarks (the acromion, coracoid process, and anterior wall of the axilla) in the proximal upper extremity to the lateral condyle (LC) of the humerus; their intersections with the radial nerve (A, B, and C) were marked. We analyzed whether the intersection positions were correlated with the connecting line lengths. The mean lengths of the connecting lines were (a) 27.24 ± 2.57, (b) 26.18 ± 2.79, and (c) 20.95 ± 1.44 cm; the distance between the intersection points and the LC of the humerus were (Aa) 7.56 ± 1.31, (Bb) 6.90 ± 2.27, and (Cc) 5.01 ± 0.83 cm; and the measured intersection points of the radial nerve in the lateral aspect of the humerus were (A) 18.48%-34.82%, (B) 13.48%-40.00%, and (C) 19.27%-28.05% of the lengths of lines a, b, and c, respectively. Our data provide a more reliable reference to predict the course of the radial nerve on the lateral humerus and define a safe zone for pin placement. Clin. Anat., 33:637-642, 2020. © 2019 Wiley Periodicals, Inc.

Development of a fetal weight chart using serial trans-abdominal ultrasound in an East African population: a longitudinal observational study

Objective

To produce a fetal weight chart representative of a Tanzanian population, and compare it to weight charts from Sub-Saharan Africa and the developed world.

Methods

A longitudinal observational study in Northeastern Tanzania. Pregnant women were followed throughout pregnancy with serial trans-abdominal ultrasound. All pregnancies with pathology were excluded and a chart representing the optimal growth potential was developed using fetal weights and birth weights. The weight chart was compared to a chart from Congo, a chart representing a white population, and a chart representing a white population but adapted to the study population. The prevalence of SGA was assessed using all four charts.

Results

A total of 2193 weight measurements from 583 fetuses/newborns were included in the fetal weight chart. Our chart had lower percentiles than all the other charts. Most importantly, in the end of pregnancy, the 10^th percentiles deviated substantially causing an overestimation of the true prevalence of SGA newborns if our chart had not been used.

Conclusions

We developed a weight chart representative for a Tanzanian population and provide evidence for the necessity of developing regional specific weight charts for correct identification of SGA. Our weight chart is an important tool that can be used for clinical risk assessments of newborns and for evaluating the effect of intrauterine exposures on fetal and newborn weight.

Systematic review of methodology used in ultrasound studies aimed at creating charts of fetal size

BACKGROUND

Reliable ultrasound charts are necessary for the prenatal assessment of fetal size, yet there is a wide variation of methodologies for the creation of such charts.

OBJECTIVE

To evaluate the methodological quality of studies of fetal biometry using a set of predefined quality criteria of study design, statistical analysis and reporting methods.

SEARCH STRATEGY

Electronic searches in MEDLINE, EMBASE and CINAHL, and references of retrieved articles.

SELECTION CRITERIA

Observational studies whose primary aim was to create ultrasound size charts for bi-parietal diameter, head circumference, abdominal circumference and femur length in fetuses from singleton pregnancies.

DATA COLLECTION AND ANALYSIS

Studies were scored against a predefined set of independently agreed methodological criteria and an overall quality score was given to each study. Multiple regression analysis between quality scores and study characteristics was performed.

MAIN RESULTS

Eighty-three studies met the inclusion criteria. The highest potential for bias was noted in the following fields: 'Inclusion/exclusion criteria', as none of the studies defined a rigorous set of antenatal or fetal conditions which should be excluded from analysis; 'Ultrasound quality control measures', as no study demonstrated a comprehensive quality assurance strategy; and 'Sample size calculation', which was apparent in six studies only. On multiple regression analysis, there was a positive correlation between quality scores and year of publication: quality has improved with time, yet considerable heterogeneity in study methodology is still observed today.

CONCLUSIONS

There is considerable methodological heterogeneity in studies of fetal biometry. Standardisation of methodologies is necessary in order to make correct interpretations and comparisons between different charts. A checklist of recommended methodologies is proposed.

Effects of calcium supplementation on fetal growth in mothers with deficient calcium intake: a randomised controlled trial

Calcium supplementation in mothers with low calcium intake has been of interest recently because of its association with optimal fetal growth and improved pre-eclampsia-related outcomes. While the effects of calcium supplementation have demonstrated benefits in prolonging gestation and subsequently improving birthweight, no specific studies have identified the longitudinal effects of supplementation on fetal growth in utero. Data were analysed in the context of the World Health Organization trial of calcium supplementation in calcium-deficient women. Five hundred and ten healthy, primiparous pregnant Argentinean women were randomised (at <20 weeks gestation) to either placebo (n = 230) or calcium supplements (1500 mg calcium/day in 3 divided doses; n = 231). Growth parameters in utero were assessed with serial ultrasound scans. Birthweight, length, head, abdominal and thigh circumferences were recorded at delivery. No differences were found in fetal biometric measurements recorded at 20, 24, 28, 32 and 36 weeks gestation between fetuses of women who were supplemented with calcium and those who were not. Similarly, neonatal characteristics and anthropometric measurements recorded at delivery were comparable in both groups. We conclude that calcium supplementation of 1500 mg calcium/day in pregnant women with low calcium intake does not appear to impact on fetal somatic or skeletal growth.

Ultrasound-derived fetal size nomogram for a sub-Saharan African population: a longitudinal study

OBJECTIVES

To create a fetal size nomogram for use in sub-Saharan Africa and compare the derived centiles with reference intervals from developed countries.

METHODS

Fetal biometric measurements were obtained at entry to antenatal care (11-22 weeks' gestation) and thereafter at 4-week intervals from pregnant women enrolled in a longitudinal ultrasound study in Kinshasa, Democratic Republic of Congo. The study population comprised 144 singleton gestations with ultrasound-derived gestational age within 14 days of the menstrual estimate. A total of 755 monthly ultrasound scans were included with a mean +/- SD of 5 +/- 1 (range, 2-8) scans per woman. Estimated fetal weight (EFW) was calculated at each ultrasound examination using the Hadlock algorithm. A general mixed-effects linear regression model that incorporated random effects for both the intercept and slope was fitted to log-transformed EFW to account for both mean growth and within-fetus variability in growth. Reference centiles (5(th), 10(th), 50(th), 90(th) and 95(th) centiles) were derived from this model.

RESULTS

Nomograms derived from developed populations consistently overestimated the 50(th) centile EFW value for Congolese fetuses by roughly 5-12%. Differences observed in the 10(th) and 90(th) centiles were inconsistent between nomograms, but generally followed a pattern of overestimation that decreased with advancing gestational age.

CONCLUSIONS

In low-resource settings, endemic malaria and maternal nutritional factors, including low prepregnancy weight and pregnancy weight gain, probably lead to lower fetal weight and utilization of nomograms derived from developed populations is not appropriate. This customized nomogram could provide more applicable reference intervals for diagnosis of intrauterine growth restriction in sub-Saharan African populations.

Sonographic fetal weight estimation using femoral length: Honarvar equation

BACKGROUND

Fetal growth is the result of interactions between various factors and can be estimated by ultrasonic measurements. Fetal femur length is a scale for estimating the fetal weight in individual races because fetal growth patterns differ among different races.

SUBJECTS AND METHODS

This was a prospective study involving 500 pregnant women at 36 weeks of gestational age. Real-time sonography was done to measure the femoral length and then the weight of the fetus was estimated by the Honarvar 2 equation. The correlation between estimated fetal weight (EFW) and real weight was tested by Pearson correlation coefficient and relationships with the age and BMI of the mother, the sex of the neonate and parity were tested by multiple regression.

RESULTS

EFW by the Honarvar 2 equation correlated significantly with the actual birthweight. Therefore, this equation is valid for fetal weight estimation. It also does not depend on the age and BMI of the mother, sex of neonate, or parity.

CONCLUSION

Ethnicity potentially plays an important role in the fetal weight estimation. The Honarvar formula produced the best estimate of the actual birthweight for Iranian fetuses, and its use is recommended.

Fetal growth in Peru: comparisons with international fetal size charts and implications for fetal growth assessment

OBJECTIVES

To compare fetal biometry measurements obtained in a Peruvian population with reference fetal size charts obtained in Peruvian and non-Peruvian populations.

METHODS

Fetal biometry measurements collected prospectively in 195 uncomplicated pregnancies were included in the presented analysis. At 20, 24, 28, 32, 36 and 38 weeks' gestation, fetal head circumference, abdominal circumference and femur diaphysis length were measured. Fetal biometry measurements were compared with fetal size charts obtained from another Peruvian and two non-Peruvian populations from North America and Europe.

RESULTS

When compared with ultrasound-based reference fetal size charts obtained from North American and European populations, fetuses from the studied population appeared to grow more slowly with advancing gestational age. This trend was not observed when a Peruvian population, similar to the one studied here, was used as a reference.

CONCLUSIONS

The results suggest that fetal growth in this Peruvian population may not be adequately assessed by using reference charts obtained from other populations and have implications for the use of growth standards in antenatal management.

Ethnicity and fetal growth in Fiji

BACKGROUND

Indigenous Fijians and the descendants of Asian Indians constitute the two major ethnic groups in Fiji. There are differences between the two groups in perinatal outcomes.

AIMS

To study fetal growth patterns in the two ethnic groups and to ascertain the influence, if any, of ethnicity on fetal growth.

METHODS

A longitudinal study was carried out on women with sure dates, regular cycles, no known risk factor complicating pregnancy and having their first antenatal examination before 20 weeks. Symphysis-fundal height, biparietal diameter, abdominal circumference and femur length were measured by the same observer at recruitment and at follow-up visits until delivery. Infant measurements were recorded soon after birth.

RESULTS

Indian babies were on average 795 g lighter, had 5.5 days shorter mean length of gestation and slower growth of biparietal diameter and abdominal circumference when compared to Fijian babies. Ethnicity of the mother was significantly associated with the difference in growth even after adjusting for other factors known to influence fetal growth.

CONCLUSION

Given the ethnic differences in fetal growth and maturation, it would be appropriate to use ethnicity-specific standards for perinatal care in Fiji.

Assessment of fetal weight based on ultrasonic femur length after the second trimester

OBJECTIVE

The ultrasonic measurement of the fetal femur length is a sensitive and precise variable for estimation of fetal growth and development. The objective of this study is to predict fetal weight in fetuses of more than 24 weeks gestation by ultrasound measurement of the femur length.

METHOD

In this study, pregnant mothers were identified by the criteria of normalities, such as: well-known LMP, regular menstrual cycles, no use of OCP for the last 3 months, no use of alcohol or cigarettes, no drug abuse, no history of diabetes or chronic HTN. Multiple gestations, congenital anomalies and still-births were excluded. Birth-weight measurements (adjusted for maternal age, baby's sex, parity and week of gestation) were taken immediately after birth.

RESULT

The relation between fetal weight and fetal femur length has been determined by cross-sectional analysis of 900 normal fetuses (> or = 25 weeks gestation) using real time ultrasonography. Mathematical modeling of the data has demonstrated that the femur growth curve is non-linear beyond 24 weeks gestation. With the aid of a scientific calculator the data were analyzed and a simple second-grade equation has been derived: EFW (kg) = 0.042FL(2) (cm)+0.32FL-1.36, S.D. approximately +/-235 g (Honarvar's Formula 2). With the use of this data, the error in estimation of EFW given FL is +/-235 g.

CONCLUSION

This simple, new and accurate equation appears to be clinically reliable and easy to use and suggests that previous normal ultrasonic fetal femur length curves for another population may underestimate or overestimate normal fetal weight for the Iranian population. Thus, our formula is an excellent means to estimate true fetal weight.

Relationship between fetal femur diaphysis length and neonatal crown-heel length: the effect of race

OBJECTIVE

To determine whether racial differences affect the relationship between the fetal femur diaphysis length and the neonatal crown-heel length.

DESIGN

A prospective study in a teaching hospital with a multiracial population.

SUBJECTS

Four hundred and fifty pregnant women (150 Malays, 150 Chinese and 150 Indians) who delivered live infants.

METHODS

Ultrasound scan measurement of the fetal femur diaphysis length was carried out within 48 h of delivery in all cases. The relationship between the neonatal crown-heel length and the femur diaphysis length was obtained by regression using the method of least squares. Dummy or indicator variables were used to determine the effect of race on the relationship.

RESULTS

The relationship between the neonatal crown-heel length and the femur diaphysis length in all three races was well described by a linear model but a quadratic model described the relationship better. There was no significant difference in relationship of the neonatal crown-heel length and the femur diaphysis length between the Malay and Chinese populations, but the relationship in the Indian population was significantly different was from both the Chinese and Malay. For a given femur diaphysis length, the crown-heel length of the Indian population was found on average to be 1.1 cm shorter than the crown-heel length of the Malay and Chinese populations.

CONCLUSION

Differences in fetal body proportions exist between some races. The longer femur diaphysis length noted in certain races does not necessarily imply that the corresponding crown-heel length is longer. These inter-racial differences may increase the error of fetal weight and length estimates if formulae, which have been derived from samples racially dissimilar to that of the target population are used.