Anne-Marie Guihard-Costa

Differential growth between the fetal brain and its infratentorial part.

From 298 normal fetuses, we established normative curves of the development of the brain in relation to gestational age and to body weight. Means and standard deviations were calculated. There exist good curvilinear relationships, expressed by polynomial models, between brain weight--body weight and brain weight--gestational age with a wider scatter in large fetuses. These results confirm literature data. Subsequently, fresh and fixed brain weights were analysed. In addition, the development of the infratentorial part of the brain was studied with the same methods and showed close relationship with age and total brain weight. The ratios: infratentorial weight/total brain weight, brain stem/total brain weight and cerebellum/total brain weight were expressed as percentages. After 20 weeks, the cerebellar growth rate was higher than that of the brain stem.

Organ weights in human fetuses after formalin fixation: standards by gestational age and body weight.

This study provides new standards of fetal organ weights (brain, heart, liver, pancreas, spleen, lungs, kidneys, adrenals, thymus, and thyroid) and body dimensions (crown–heel and crown–rump lengths, head circumference, and foot length). Subjects came from a large dataset including more than 4000 fetuses autopsied in fetopathology units of pediatric hospitals in Paris between 1986 and 2001. From this dataset, 673 subjects were carefully selected by exclusion of multiple pregnancies, macerated and malformed fetuses, subjects with abnormal karyotypes, and those with severe infections. Fetal age ranged from 9 to 42 gestational weeks, with a very large sample of fetuses in the first half of gestation. Each organ was weighed after fixation in formalin. The standards were computed in relation to age and body weight. The mathematical models used to fit the percentile growth curves were carefully selected for each organ or dimension. This study, based on reliable methodology, affords a whole set of accurate growth standards useful for pathologists.

Validation of Ultrasound Techniques Applied to Body Fat Measurement

Aims: To evaluate the accuracy of body fat percentage (BF%) estimates from a portable, non-traumatizing ultrasound device with high accuracy and reliability compared to dual-energy X-ray absorptiometry (DEXA), the reference technique. Design: Cross-validation between ultrasound technique (UT), DEXA, air displacement plethysmography (ADP) and bioelectrical impedance (BIA) was developed in the study. Subjects: A total of 89 healthy subjects (41 women, 48 men), aged 48.4 ± 17.7 (mean ± SD), with Body mass index (28.5 ± 7.7 kg/m2) and body fat DEXA (29.6 ± 10.8 kg) participated. Methods: BF% was measured using an UT associated with anthropometric parameters and simultaneously, with the DEXA reference technique, BIA and ADP. Results: UT estimates of BF% were better correlated with those of DEXA in both males and females (r = 0.98, SEE = 2.0) than with ADP (r = 0.94, SEE = 3.7) or BIA (r = 0.92, SEE = 4.4). The UT in both genders was better (TE = 1.0) than BIA (TE = 2.6) and ADP (TE = 3.0). The 95% limits of agreement were also better for the UT (–2%; 2%) than with BIA (–5.1%; 4.9%) and ADP (–6.3%; 5.3%). Conclusions: The limits of agreement with BIA and ADP are unacceptably high compared to a DEXA measure criterion. The use of a new portable device based on a UT produced a very accurate BF% estimate in relation to the DEXA reference technique.

Biometry of face and brain in fetuses with trisomy 21.

The aim of this study was to specify the early setting of the particular craniofacial morphology in Down syndrome during the fetal period from data based on postmortem examinations. The study included 1277 fetuses at 15–38 gestational weeks (GW): 922 control fetuses and 355 fetuses with trisomy 21, selected from fetopathology units in Paris. Body weight (BW) and nine dimensions of the face, skull, and brain were recorded: the outer and inner canthal distances (OCD, ICD), biparietal diameter (BPD), head circumference (HC), brain weight (BrW), occipitofrontal diameters of left and right hemispheres (lOFD, rOFD), weight of the infratentorial part of the brain (IBW), and maximal transversal diameter of the cerebellum (CTD). Four ratios were computed: BPD/HC, OCD/BPD, BrW/BW, IBW/BrW. Differences between trisomic fetuses and control fetuses were tested by age interval. Results showed that BW, rOFD, and lOFD were lower in trisomic fetuses as early as 15 GW. Cerebellar hypoplasia included lower IBW and CTD in trisomic fetuses. The IBW/BrW ratio was higher in trisomic fetuses, showing that growth restriction affected the infratentorial part of the brain less than the supratentorial part. Early brachycephaly was found in trisomic fetuses, with higher values of BPD and BPD/HC from 15 GW. ICD and OCD were not significantly different in the two groups, but OCD/DBP ratio was lower in trisomic fetuses. These results confirm the early phenotypical expression of trisomy 21 on craniofacial morphology, associated with a marked restriction of brain growth, especially in the supratentorial part.

Sexual Differences in Anthropometric Measurements in French Newborns

Sexual differences in anthropometric measurements have been studied in a sample of 17,787 preterm and full-term infants, born between 1980 and 1990 in the maternity of Clamart Hospital (Hauts-de-Seine, France). Body weight, body length, head and chest circumferences were found significantly larger in male newborns. Conversely, the subscapular and tricipital skinfold thicknesses had higher values in females. Such greater fatness in females could be related to the better outcome in neonates of this sex. The weight-for-height indices, however, did not show this female advantage: the body mass index (BMI) and the body weight/body length index were greater in male neonates, the ponderal index (PI) showed no sexual difference.

Predictors of body satisfaction: differences between older men and women's perceptions of their body functioning and appearance.

Objective: This article examines the predictors of body satisfaction among older men and women. Method: A self-reported questionnaire on body satisfaction (focused on body appearance and functioning), health, physical activity, and sociodemographic characteristics was completed by 384 older adults twice, at a year’s interval. Women (n = 243) were on average 70.3 ± 7.9 years old, and men 70.9 ± 7.5 years old. Results: Body mass index was found to be the strongest predictor of satisfaction with body appearance for both genders, along with body functioning in the case of men. Regarding satisfaction with body functioning, functional limitations were women’s most important predictor of satisfaction, whereas for men body appearance was more important. Discussion: Men seemed to link satisfaction with body appearance more closely to body functioning than did women. Gender differences suggest that interventions to improve body satisfaction must be gender specific, particularly those relating to body functioning.

Gender differences in neonatal subcutaneous fat store in late gestation in relation to maternal weight gain

Objective : To study gender differences in fat store in human newborns and their relation to duration of gestation and maternal weight gain. Methods : The ratios subscapular skinfold thickness/body weight (SST/BW) and tricipital skinfold thickness/body weight (TST/BW) were calculated in a sample of 13 609 premature and term neonates from the maternity hospital of Clamart, Hauts-de-Seine, France. Results : Whereas BW, SST and TST increased with gestational age, SST/BW and TST/BW ratios decreased regularly, in males as in females. This result reflects a progressive reduction of subcutaneous fat store per body weight unit as the duration of gestation increases. Males had smaller values of SST/BW and TST/BW ratios than females whatever the gestational age. Increasing maternal weight gain during the third gestational trimester did not improve the subcutaneous fatness per body weight unit of the newborn. Earlier amount of maternal weight gain had an effect on the TST/BW index exclusively in females. Conclusions : In newborns, a gender difference was observed in the ratio of subcutaneous fat per unit of body weight; this ratio is lower in males than in females. This result argues for a gender difference in mobilization of fat store to ensure normal growth in the last weeks of pregnancy: males lose more fat but gain more weight than females in this period. Late maternal weight gain does not affect the proportion of subcutaneous fatness by body weight unit in both genders.

Only two-phase models, computed independently for males and females, are appropriate to describe fetal head growth

Objective: To establish an accurate mathematical model describing fetal head growth, taking into account gender differences and changes in growth rate during gestation. Methods: Ultrasound measurements of head circumference and biparietal diameter were made on 1,336 normal fetuses (684 males and 652 females) in the Maternité Régionale de Nancy (France). A new two-phase model, taking into account an alteration in growth kinetics at 30 gestational weeks, was computed independently for male and female data. The accuracy of this model was tested and compared with three current mathematical models: a linear-quadratic, a linear-cubic, and the Rossavik and Deter (1984) models. Results: In all models, including ours, the coefficients of determination (R2) were high (≧0.999), so long as male and female data were computed separately. However, the standard error estimates (SEE) of our two-phase model were much lower (0.13 ≤ SEE ≤ 0.57) than the SEE of the three other models when computed over the whole gestational period (0.49 ≤ SEE ≤ 2.69); nevertheless, when these three other models were computed for these two successive periods, their SEE decreased, and data fitting was improved. Conclusion: Only two-phase mathematical models, computed independently for male and female data, accurately describe the kinetics of fetal head growth. They should be used to calculate growth standards and to perform an exact diagnosis of impaired growth.

Ultrasound measurement of total body fat in obese adolescents

Background/Aims: To compare body fat (BF) measurements obtained with a new ultrasound method with those assessed by dual-energy X-ray absorptiometry (DEXA) in obese adolescents. Methods: In 94 adolescents (57 females and 37 males) aged 12–19 years and body mass index (BMI) exceeding 30 kg·m–2, the z-score BMI for age was 6.7 (adolescent girls) and 6.6 (adolescent boys) >97th percentile. BF was measured using DEXA and a method based on ultrasound measurements, body weight, height, abdominal circumference and mid-thigh circumference. Results: Obesity class I was noted in 39%, II in 28% and III in 33% of the patients. BF by ultrasound correlated closely with BF by DEXA, in both females (r = 0.958) and males (r = 0.981), with standard errors of the estimates (SEE) being 2.9 and 2.5 kg, respectively. The ultrasound method was more accurate than the skinfold technique (n = 24; SEE: 2.2 vs. 6.5 kg, respectively). In 13 adolescents who had marked weight loss after 6 months of treatment, the decrease in DEXA-measured BF correlated closely with the decrease in ultrasound-measured BF (r = 0.95). Conclusions: Our innovative portable ultrasound technique has advantages in terms of reliability, reproducibility, accuracy and costs for screening and monitoring obese adolescents. A patent application has been submitted. Our method should prove valuable for epidemiological studies.

A longitudinal study of fetal growth variability.

The aim of this study was to assess the variability in individual fetal growth rhythms in comparison to averaged standard curves obtained from cross-sectional data. Biparietal diameter (BDP), abdominal transverse diameter (ATD) and femur length (FL) were measured by ultrasonography in 24 normal subjects, and the variance in growth rates determined for four time intervals: 12–26, 26–34, 34–37 and 37–39 weeks gestation. BPD, ATD and FL growths were always linear until 26 weeks with low variances in growth rates. Growth rates decreased thereafter whereas related variances increased significantly with a great diversity in individual growth trajectories. This study questions the relevance of mathematically smoothed curves which lead to an erroneous impression of growth trajectory uniformity when ultrasonography does not seem to be able to predict accurately newborn biometrical characteristics by the end of gestation.