Influence of fetal fat on the ultrasound estimation of fetal weight in diabetic mothers.

Currently available formulas for the estimation of fetal weight assume uniform density of tissue. Because fat tissue is less dense than lean body mass, we hypothesized that the sonographic overestimation of fetal weight in infants of diabetic mothers is the consequence of an elevated proportion of body fat, resulting in a lower body density. We prospectively examined 52 children of diabetic mothers. Each had ultrasound estimation of fetal weight within 7 days of delivery and estimates of neonatal body composition made from anthropometric evaluation within 48 hours of birth. Ultrasound estimates of fetal weight were considered acceptable if they were within 10% of actual birth weight. There was no difference in mean birth weight between those overestimated (N = 22) and those underestimated (N = 8). The sum of skinfolds from two sites, the ponderal index, and percent body fat were all significantly greater in the neonates with sonographic overestimation of fetal weight. Lean body mass was significantly greater (P less than .05) in infants whose sonograms underestimated birth weight. When all subjects were included, a significant correlation was found between the degree of error in the ultrasound estimation of fetal weight and the ponderal index (r = 0.40, P less than .01), the sum of the skinfold measurements (r = 0.29, P less than .05), and the present body fat (r = 0.28, P less than .05). These data suggest that increased body fat in infants of diabetic mothers is associated with sonographic overestimation of fetal weight.     

The effect of gender and gestational diabetes mellitus on cord leptin concentration

OBJECTIVE: The purpose of this study was to determine the relationship of neonatal sex and gestational diabetes mellitus on cord leptin concentration and to determine whether cord leptin has a stronger correlation with fat mass compared with birth weight or lean body mass. We hypothesized that there are no significant differences in fetal leptin concentration between male and female or between neonates of mothers with gestational diabetes mellitus and control neonates, when adjusted for body composition. STUDY DESIGN: Cord blood leptin concentrations were measured in newborn infants of 78 women (44 control neonates and 34 gestational diabetes mellitus). Of the 78 neonates, 32 babies were female, and 46 babies were male. Birth weights were measured with a calibrated scale, and body compositions were measured by total body electrical conductivity. RESULTS: Estimated mean gestational age at delivery was 39.1 +/- 1.1 weeks for control neonates versus 38.6 +/- 1.3 weeks for neonates of mothers with gestational diabetes mellitus (P =.01). The fat mass for the control neonates and neonates of mothers with gestational diabetes mellitus was 0.36 +/- 0.15 kg versus 0.48 +/- 0.21 kg (P =.01); the percent body fat for the control neonates and neonates of mothers with gestational diabetes mellitus was 10.5% +/- 3.8% versus 13.2% +/- 4.3% (P =.006), respectively. There was no significant difference in cord leptin concentration between male and female neonates (16.0 +/- 13.8 ng/dL vs 12.7 +/- 12.8 ng/dL, P =.24). Cord leptin concentrations (18.1 +/- 16.2 ng/dL vs 10.9 +/- 9.5 ng/dL, P =.02) were significantly greater in neonates of mothers with gestational diabetes mellitus than in control neonates. In all subjects, cord leptin was significantly correlated with percent body fat (r = 0.51, P <.0001), fat mass (r = 0.49,P <.0001), and birth weight (r = 0.25, P =.03). After the adjustment for fat mass, there was no significant difference in cord leptin concentration between control neonates and neonates of mothers with gestational diabetes mellitus (P =.20), but there was a significant difference between male and female neonates (P =.04). However, when an adjustment was made for both fat mass and lean body mass, there was no longer a significant difference between male and female neonates (P =.12) CONCLUSION: The differences in cord leptin concentration between male and female neonates and between infants of women with gestational diabetes mellitus and control neonates are related to differences in body composition.     

Evaluation of body composition of large-for-gestational-age infants of women with gestational diabetes mellitus compared with women with normal glucose tolerance levels

OBJECTIVE: The purpose of this study was to determine whether there is a difference in body composition and the factors that are associated with fat mass in the large-for-gestational-age infants of women with gestational diabetes mellitus compared with the large-for-gestational-age infants of women with normal glucose tolerance levels. STUDY DESIGN: Large for gestational age was defined as weight >90th percentile for gestational age, race, and sex on the basis of our population's normative data. Anthropometric measurements and/or total body electrical conductivity estimated body composition that included fat mass, percent body fat, and lean body mass were obtained. Multiple stepwise regression was used to determine factors correlating with fat mass. RESULTS: Fifty cases of women with gestational diabetes mellitus and 52 cases of women with normal glucose tolerance levels were evaluated. Infants of mothers with gestational diabetes mellitus had increased fat mass (662 vs 563 g; P = .02) and percent body fat (16.2% vs 13.5%; P = .002) but decreased lean body mass (3400 vs 3557 g; P = .0009), as compared with infants of mothers with normal glucose tolerance levels, despite similar birth weights. Stepwise regression on all 102 women showed gestational age and a diagnosis of gestational diabetes mellitus correlated with fat mass (r2 = 0.11; P = .001). For gestational diabetes mellitus alone, both gestational age and fasting value of the oral glucose tolerance test correlated with fat mass and percent body fat (r2 = 0.33 [P = .0009] and r2 = 0.26 [P = .005], respectively). CONCLUSION: Large-for-gestational-age infants of mothers with gestational diabetes mellitus have increased fat mass and decreased lean body mass compared with infants of mothers with normal glucose tolerance levels. In gestational diabetes mellitus, gestational age and fasting value of the oral glucose tolerance test correlated best with fat mass.     

Relationship between body fat distribution and bone mineral density in premenopausal Japanese women

OBJECTIVE: To investigate the relationship between body fat distribution and bone mineral density (BMD). METHODS: Subjects were 282 premenopausal women (mean age +/- standard deviation [SD], 38.8 +/- 8.5 years; range, 20-51 years) with regular menstrual cycles. Baseline characteristics included age, age at menarche, height, weight, body mass index ([BMI], weight/height(2)), and parity. Anthropometric characteristics including the ratio of trunk fat mass to leg fat mass (trunk-leg fat ratio), percentage of body fat, and total body lean mass were measured by whole-body scanning with dual-energy x-ray absorptiometry. Lumbar spine BMD (L2-4) was also measured by dual-energy x-ray absorptiometry. Correlations of BMD to baseline and anthropometric characteristics were investigated using univariate and multivariate analysis. RESULTS: Although height, trunk-leg fat ratio, and total body lean mass were positively correlated with lumbar spine BMD (r =.18, P <.01; r =.17, P <.01; and r =.25, P <.001; respectively), age at menarche was inversely correlated with BMD (r = -.19, P <.01). On multivariable analysis, trunk-leg fat ratio, height, age at menarche, and total body lean mass were still independently correlated with lumbar spine BMD (P <. 05). However, total fat mass was not correlated with BMD. CONCLUSION: Upper body fat distribution rather than overall adiposity is associated with lumbar spine BMD in premenopausal women. Humoral factors associated with body fat mass appear to influence lumbar spine BMD.     

Beginning regular exercise in early pregnancy: effect on fetoplacental growth

OBJECTIVE: Our purpose was to test the null hypothesis that beginning regular, moderate-intensity exercise in early pregnancy has no effect on fetoplacental growth.Study Design: Forty-six women who did not exercise regularly were randomly assigned at 8 weeks either to no exercise (n = 24) or to weight-bearing exercise (n = 22) 3 to 5 times a week for the remainder of pregnancy. Outcome variables included antenatal placental growth rate and neonatal and placental morphometric measurements. RESULTS: The offspring of the exercising women were significantly heavier (corrected birth weight: 3.75 +/- 0.08 kg vs 3.49 +/- 0.07 kg) and longer (51.8 +/- 0.3 cm vs 50.6 +/- 0.3 cm) than those born to control women. The difference in birth weight was the result of an increase in both lean body mass and fat mass. In addition, midtrimester placental growth rate was faster (26 +/- 2 cm(3)/wk vs 21 +/- 1 cm(3)/wk) and morphometric indexes of placental function were greater in the exercise group. There were no significant differences in neonatal percentage body fat, head circumference, ponderal index, or maternal weight gain. CONCLUSIONS: These data indicate that beginning a moderate regimen of weight-bearing exercise in early pregnancy enhances fetoplacental growth.     

Impact of maternal cigarette smoking on fetal growth and body composition

OBJECTIVE: The aim of this study was to determine the impact of maternal cigarette smoking on the fetal accretion of fat and lean body mass. We hypothesized that maternal smoking would result in a reduction in the deposition of lean body mass. STUDY DESIGN: Longitudinal ultrasonographic examinations on 65 singleton fetuses without anomalies of smoking mothers were compared with 36 singleton fetuses without anomalies of nonsmoking mothers. A total of 214 ultrasonographic examinations were performed between 27 and 37 weeks' gestation. All subjects underwent at least 2 ultrasonographic examinations separated by 4 weeks. We compared the slopes of the growth curves for individual morphometric parameters including head circumference, femur length, abdominal circumference, thigh muscle area, thigh fat area, estimated fetal weight and percentage of thigh fat between groups. Analysis was performed with a repeated measures analysis of covariance. Potential covariates included prepregnancy body mass index (in kilograms per square meter), weight gain during pregnancy, maternal age, parity, and fetal sex recorded at birth. Demographic variables are expressed as mean +/- SD; fetal measurements are expressed as mean +/- SE. Both t tests and chi(2) analyses were used to compare groups with respect to demographic variables. P <.05 was accepted for significance. RESULTS: There were no significant differences between groups in maternal prepregnancy weight, maternal height, maternal prepregnancy body mass index, weight gain in pregnancy, parity, or fetal sex. Smokers were younger than nonsmokers (smokers, 23.7 +/- 6.0 years; nonsmokers, 31.8 +/- 6. 0 years; P <.0001), and neonatal weight was reduced among smokers (smokers, 3269 +/- 507 g; nonsmokers, 3519 +/- 411 g; P <.01). There were no differences in the growth rates of head circumference (P =. 79) and femur length (P =.67). Growth rates of abdominal circumference (smokers, 9.0 +/- 0.3 mm/wk; nonsmokers, 10.3 +/- 0.5 mm/wk; P =.01), estimated fetal weight (smokers, 171 +/- 5.4 g/wk; nonsmokers, 193 +/- 8.0 g/wk; P =.008), and muscle area (smokers, 64. 1 +/- 3.8 mm(2)/wk; nonsmokers, 76.4 +/- 5.6 mm(2)/wk; P =.03) were significantly reduced among smokers. There was a reduction in the rate of fat deposition in the thighs of fetuses of smoking mothers (smokers, 38.7 +/- 3.7 mm(2)/wk; nonsmokers, 54.6 +/- 5.4 mm(2)/wk; P =.004); however there was no absolute difference in the amount of fat measured in the thigh between 33 and 37 weeks' gestation. CONCLUSION: We detected reduced fetal growth that selectively affected abdominal circumference and peripheral muscle mass while not affecting head circumference and femur length in fetuses of smoking mothers. The effect of cigarette smoking on fetal fat deposition was less clear. Cigarette smoking appears to have a selective effect within lean body mass compartments, with affected compartments including peripheral fetal muscle. The findings of a reduction in abdominal circumference growth compared with control subjects in combination with no difference in subcutaneous fat content beyond 33 weeks' gestation are potentially explained by a reduction in fetal liver size that may result from maternal smoking.     

Body fat distribution and body composition during GnRH agonist therapy

OBJECTIVE: To identify the effects of GnRH agonist therapy on body composition (lean and fat mass components) and body fat distribution. METHODS: Fifteen women with uterine leiomyomas were given a GnRH agonist (leuprorelin acetate, 3.75 mg) monthly for 4 months. Weight, height, and body mass index (BMI, weight/height) were recorded. Regional and total body composition, trunk-leg fat ratio, bone mineral density of the lumbar spine (L2-L4), and total body were assessed by whole-body scanning with dual-energy x-ray absorptiometry before and after treatment. Uterine volume was measured by transabdominal ultrasonography. RESULTS: The mean (+/- standard deviation [SD]) lean mass of total body, trunk, and leg decreased significantly (36.3 +/- 4.9 to 35.4 +/- 4.4 kg, P <.01; 18.8 +/- 2.8 to 18.1 +/- 2.8 kg, P <.05; and 11.4 +/- 1.8 to 11.1 +/- 1.6 kg, P <.05; respectively), whereas body fat mass, percentage of body fat, and trunk fat mass increased significantly (20.8 +/- 4.8 to 21.8 +/- 4.6 kg, P <.01; 34.9 +/- 5.9 to 36.5 +/- 5.2%, P <.01; and 8.6 +/- 3.0 to 9.3 +/- 3.0 kg, P <.01; respectively). Trunk-leg fat ratio increased significantly (1.03 +/- 0.32 to 1.12 +/- 0.33, P <.05). Weight, BMI, arm tissue composition (lean and fat mass components), and leg fat mass did not change during 4 months of GnRH agonist therapy. Bone mineral density and uterine volume decreased significantly. CONCLUSION: Hypogonadism by GnRH agonist therapy induces lean mass loss, increased adiposity overall, and upper body fat accumulation.     

Relationship of paternal factors to birth weight

OBJECTIVE: To investigate the relationship between paternal characteristics and birth weight. STUDY DESIGN: A total of 241 gravidas with uncomplicated, singleton, term pregnancies were studied. Maternal demographic and pregnancy-specific characteristics were used to calculate the expected birth weight for each fetus using a previously validated birth weight prediction equation. The additional independent predictive value of 4 paternal variables was assessed using multiple regression. RESULTS: Before adjustment for other variables, paternal height and weight significantly correlated with birth weight, but paternal age and body mass index did not. After controlling for maternal and pregnancy-specific factors that are known to influence fetal weight, only paternal height was significant as a predictive variable. The proportion of variance in birth weight that could be independently explained by paternal height was 2%. A 10-g gain in fetal weight was associated with each centimeter of increase in paternal height (P < .02). Using the resulting combination equation that included paternal height as a variable, 31% of the variance in term birth weight could be explained, and birth weights could be accurately predicted to within +/- 8.3% (+/- 288 g). Fathers with heights 2 SD above and below the mean had the term birth weight of their offspring increased and diminished by 125 g, respectively. CONCLUSION: Paternal height explains an independent portion of the variance in term birth weight among normal newborns of up to 250 g that cannot be explained by other maternal or pregnancy-specific factors. Paternal age, weight and body mass index do not independently influence birth weight.     

Visceral fat is more important than peripheral fat for endometrial thickness and bone mass in healthy postmenopausal women

OBJECTIVE: The purpose of this study was to investigate the influence of body mass index and body composition on endometrial thickness and bone mass. STUDY DESIGN: This was a cross-sectional study that included 531 healthy postmenopausal women aged 48 to 65 years. Endometrial thickness was measured as double-layer thickness. Body composition was measured by dual energy x-ray absorptiometry, which divides the body into fat mass, lean mass, and bone mass, both for the total body and regional body compartments. An abdominal region was inserted manually. Statistics were Pearson correlations and analysis of variance. RESULTS: Endometrial thickness and total body bone mass were correlated, respectively, to body mass index (r = 0.14, P <.01; r = 0.35, P <.001), total body fat mass (r = 0.14, P <.01; r = 0.38, P <.001), abdominal fat mass (r = 0.16, P <.001; r = 0.33, P <.001), peripheral fat mass (r = 0.10, P <.05; r = 0.41, P <.001), and abdominal/peripheral fat mass (r = 0.12, P <.01; r = 0.11, P <.01). CONCLUSION: High body mass index and abdominal fat distribution correlate with increased endometrial thickness and bone mass.     

The influence of obesity and gestational diabetes mellitus on accretion and the distribution of adipose tissue in pregnancy

OBJECTIVE: The purpose of this study was to evaluate the effect of pregravid obesity and gestational diabetes mellitus (GDM) on the longitudinal accretion and distribution of adipose tissue in pregnancy. STUDY DESIGN: Women with normal glucose tolerance and GDM were evaluated before conception, early (12-14 weeks) and late (33-36 weeks) in gestation. Fat mass, lean body mass, and percent body fat were assessed longitudinally with hydrodensitometry. Serial biceps, triceps, subscapular, iliac, costal, mid thigh, and lower thigh skinfold measurements quantified the changes in fat mass distribution. Pregravid obesity was defined as >25% body fat. RESULTS: Subjects included 19 patients with GDM (5 lean women, 14 obese women), and 33 patients with normal glucose tolerance (controls; 12 lean women, 21 obese women). GDM and control subjects were similar in pregravid percent body fat (29.6% vs 27.9%, P=.47) and fat mass (20.8 kg vs 18.2 kg, P=.37). Values for subjects with GDM and controls were also similar in terms of percent body fat, fat mass, and weight gained (change in percent body fat, -0.7% vs 1.9% [P=.07]; change in fat mass, 3.8 kg vs 5.0 kg [P=.08]; change in weight, 12.0 kg vs 13.2 kg [P=.35]). Lean subjects gained more percent body fat compared with obese subjects (change in percent body fat, 3.3% vs 0.1% [P=.004]) but gained similar amounts of fat mass (change in fat mass, 4.7 kg vs 4.2 kg [P=.58]), lean body mass (7.6 kg vs 8.8 kg [P=.18]), and weight (change in weight, 12.3kg vs 13.0 kg [P=.61]) The distribution of adipose tissue that was accumulated as estimated with skinfold measurements was similar between patients with GDM and glucose tolerance (P>.05 for all changes in skinfolds), but significantly different between lean and obese patients (P<.05 for all changes in skinfolds). Lean women gained a predominance of adipose tissue peripherally over that in obese women. CONCLUSION: Lean women accrue significantly more fat mass than obese women, regardless of glucose tolerance. Pregestational obesity rather than GDM influences the distribution of adipose accretion.     

The relationship among intrauterine growth, insulinlike growth factor I (IGF-I), IGF-binding protein-3, and bone mineral status in newborn infants

Insulinlike growth factors (IGFs) exert profound effects on somatic growth and cellular proliferation of many tissues and play an essential role in bone metabolism. The aim of this study was to investigate how fetal growth and bone mineralization correlate with IGF-I and IGF-binding protein-3 (IGFBP-3) levels of newborn infants and their mothers. In addition, we aimed to determine the predictive value of anthropometric measurements on variability in bone mineral status. Umbilical cord venous blood samples were obtained at delivery from 100 term newborn infants. Forty of the newborn infants had birthweights appropriate for gestational age (AGA), 30 were small for gestational age (SGA), and 30 were large for gestational age (LGA). Data were acquired using whole-body dual-energy X-ray absorptiometry scanner with a pediatric platform. Umbilical cord serum IGF-I concentrations were higher in LGA newborns ( P < 0.01), but lower in SGA newborns ( P < 0.01) than in AGA newborns. Umbilical cord serum IGFBP-3 concentrations in LGA newborns were significantly greater than in SGA and AGA newborns ( P < 0.01 and P < 0.01, respectively). Whole-body bone mineral density (WB BMD) was higher in LGA babies (0.442 +/- 0.025 g/cm2 [SD]; P < 0.01) but lower in SGA (0.381 +/- 0.027 g/cm 2; P < 0.0001) than in AGA babies (0.426 +/- 0.022 g/cm2). WB BMD and content (WB BMC) were correlated significantly with birthweight, birth height, head circumference, body mass index (BMI) of the infants; ponderal index and triceps skinfold thickness (reflecting fat stores) of the infants; cord serum IGF-I concentration, serum IGF-I concentration of the mothers; and fat mass, proportionate fat mass, weight, and BMI of the mothers. In contrast, WB BMC was also correlated positively with cord serum IGFBP-3 concentration and gestational age, and WB BMD was positively correlated with serum IGFBP-3 levels of the mothers. Umbilical cord serum IGF-I concentration of the infants was correlated significantly with the concentration of the mothers ( R = 0.232; P = 0.020). Umbilical cord serum IGF-I and IGFBP-3 concentrations were correlated significantly with the fat mass, gestational age, birthweight, birth height, head circumference, and BMI of the infants. Umbilical cord IGF-I concentration was also correlated with ponderal index and triceps skinfold thickness of the infants, maternal weight, BMI, and proportionate fat mass of the infants. Stepwise multiple regression analyses showed no significant relation between bone indices (WB BMD, WB BMC) and the infant's or mother's variations including serum IGF-I and IGFBP-3 concentrations. Birthweight and gestational age are related to bone indices. However, the present study does not provide support for the hypothesis that serum IGF-I and IGFBP-3 levels of infants and their mothers may play a major role in the regulation of bone metabolism in the developing skeleton.     

Maternal birth weight in relation to plasma lipid concentrations in early pregnancy

OBJECTIVE: The purpose of this study was to determine the extent to which, if at all, maternal weight at birth is related to dyslipidemia during early pregnancy, which is a risk factor for preeclampsia. STUDY DESIGN: This hospital-based prospective cohort study included 1000 women who initiated prenatal care before 16 weeks of gestation. Participants provided information about their birth weight and other sociodemographic and reproductive covariates. Plasma triglyceride, high-density lipoprotein cholesterol, and total cholesterol concentrations were measured at approximately 13 weeks of gestation. beta coefficients and standard errors were estimated by multiple linear regression; odds ratios and 95% confidence intervals were estimated by logistic regression. RESULTS: Maternal birth weight was correlated negatively with triglycerides (r =-0.12; P =.001) and was correlated positively with high-density lipoprotein cholesterol (r =0.08; p =.02) but not statistically significantly related with total cholesterol (r =-0.004; P=.91). After adjusting for potential confounders, women who weighed <2500 g at birth had higher triglyceride and total cholesterol concentrations (beta=23.4 mg/dL [P<.001]; beta =2.6 mg/dL [P =.585], respectively) and lower high-density lipoprotein cholesterol concentrations (beta =-3.2 mg/dL; P=.105), when compared with women who weighed 3000 to 3499 g at birth. Women who were born small (<2500 g) and became overweight (body mass index, >or=25 kg/m(2)) in adulthood had less favorable lipid profiles than their counterparts who weighed >or=2500 g at birth and remained lean (body mass index, <25 kg/m(2)). CONCLUSION: Our findings suggest that factors that are related to growth in utero may help to predict the subsequent risk of altered lipid metabolism during pregnancy, which may, in turn, be causally related to the occurrence of preeclampsia.     

Reduction of subcutaneous mass, but not lean mass, in normal fetuses in Denver, Colorado

OBJECTIVE: To test the hypothesis that reduced birth weight in normal fetuses born at moderately high altitude (Denver), compared with the birth weight in normal fetuses born at sea level (Milan), is caused by a reduction in both lean mass and subcutaneous fat mass. STUDY DESIGN: Ninety-four normal singleton pregnancies (46 in Denver, 48 in Milan) had serial ultrasonographic axial images obtained to assess subcutaneous tissues of fetuses as a measure of body fat. The abdominal wall thickness and mid upper arm and mid thigh were examined. The equation was: Subcutaneous tissue equals total cross-sectional area minus bone and muscle area. Lean mass included the area of muscle and bone, head circumference, and femur length. RESULTS: Gestational age at delivery was similar between groups. Birth weight was less at Denver's altitude (2991 +/- 79 g versus 3247 +/- 96 g; P =.04). Abdominal wall thickness, mid upper arm, and mid thigh subcutaneous tissues measurements were significantly reduced at Denver's altitude and increased further in significance with advancing gestational age. Lean mass measurements were similar between groups. CONCLUSIONS: The reduced birth weight of the newborns in Denver was the result of a reduction in fetal subcutaneous fat tissue and not lean mass. Ultrasonography can be used to follow subcutaneous measurements longitudinally and to detect differences, and potentially disease processes, in study populations.     

Leptin as an acute stress-related hormone in the fetoplacental circulation

OBJECTIVE: To investigate the relationship between fetoplacental leptin secretion and blood gases. METHODS: We measured the levels of umbilical arterial and venous leptin, umbilical cord gas, umbilical venous blood glucose, and estradiol-17beta (E2) in 89 pregnant women. Correlation between the leptin levels and other variables (gestational age, birth weight, maternal body weight, height, body mass index, maternal body weight gain, placental weight, umbilical cord gas data, and levels of umbilical venous blood glucose and E2) were examined statistically. RESULTS: Umbilical arterial and venous leptin levels were 7.64 +/- 12.76 and 7.76 +/- 13.17 (ng/mL), respectively, correlating positively with carbon dioxide pressure levels (r = 0.446, P <.001; r = 0.406, P <.001, respectively) and correlating inversely with pH (r = -0.337, P =.001; r = -0.247, P =.019, respectively). Umbilical venous glucose, E2, and other factors did not correlate with leptin levels. CONCLUSION: Leptin secretion into the fetoplacental circulation may be associated with fetal hypercapnia, suggesting two important roles for leptin: one for basal control of fetal fat tissue and one as an acute stress-related hormone.     

Placental nutrient transfer capacity and fetal growth

The objective of this study was to determine whether the ability of the human placenta to transfer glucose and fatty acids is related to normal fetal growth. The intrinsic nutrient transport capacity of the placenta was measured under standardized conditions during in vitro perfusion of 30 human term placentas and related to birth weight (range 2640-4640g), birth weight centile (8th-99th), ponderal index (2.43-3.69), placental weight (418-1030g) and placental:fetal weight (0.14-0.31). There was no statistically significant change in the rate of nutrient transfer per placenta or per kg fetal weight, with birth weight, birth weight centile, ponderal index, placental weight and placental:fetal weight. There was a weak but significant relationship (P=0.020, r(2)=9 per cent) between the ratio of glucose to fatty acid transport and birth weight centile, largely due to the high ratio found in the lowest birth weight quartile where the babies are thinnest. This study provides no evidence that placental nutrient transport capacity limits fetal growth across a wide range of birth weights in normal pregnancies. It is proposed that the fetus itself may regulate placental nutrient transport in vivo via the fetal cardiac output and the rate of fetal nutrient utilization.     

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.     

Anthropometric estimation of maternal body composition in late gestation

OBJECTIVE: To construct a model to estimate maternal body composition in late gestation using anthropometric measurements. METHODS: Twenty healthy pregnant women at 30 weeks' gestation had estimates of body composition using hydrodensitometry, with corrections for residual lung volume, and total body water using H(2)(18)O (development group). Total body water was estimated from (18)O abundances measured by gas-isotope-ratio mass spectrometry. Maternal age, height, weight, and seven skinfold sites were correlated with fat mass using stepwise regression analysis. The anthropometric model to estimate fat mass was then tested prospectively in a second group of 20 subjects and correlated with underwater weighing and total body water measurements (validation group). Statistical analysis used chi(2), paired t and Wilcoxon sign-rank tests. RESULTS: There were no statistically significant differences in maternal demographics between groups. The fat mass of development group subjects using underwater weighing and total body water was 22.7 +/- 7.6 kg. Using the development group, a model was derived that explained 91% of the variance in fat mass by underwater weighing and total body water using maternal weight and triceps, subscapular, and suprailiac skinfolds (r(2) = 0.91, P <.001). When tested prospectively in the validation group, the correlation remained statistically significant (r(2) = 0.89, P <.001). There was no statistically significant (P =.88) difference between the anthropometric estimates of fat mass and underwater weighing and total body water measurements (95% confidence interval -2.476, 2.748 kg of fat mass). CONCLUSION: This anthropometric model can be used to predict maternal fat mass in late gestation.     

妊娠期糖尿病患者孕晚期体质量增长与糖化血清白蛋白、内脂素水平及新生儿体成分的相关性研究

目的:探讨非肥胖的妊娠期糖尿病(GDM)患者孕晚期体质量增长与母体糖化血清白蛋白(GA)、内脂素水平及新生儿体成分的相关性。方法:200例GDM患者[孕前体质量指数(BMI)均25 kg/m~2]进入本研究,以孕28周至分娩期体质量增长速度分为过度增重GDM组(n=77)和适宜增重GDM组(n=123)。比较不同组别GA、内脂素等糖脂代谢指标及新生儿出生体质量、体脂百分含量的差异;进一步分析GDM患者妊娠晚期体质量增长与上述指标的相关性。结果:1过度增重GDM组患者GA、糖化血清蛋白(HbA1c)、内脂素及血脂总胆固醇(TC)、甘油三酯(TG)、低密度脂蛋白(LDL)、极低密度脂蛋白(VLDL)水平均高于适宜增重GDM组(P0.05)。2两组平均分娩孕周、新生儿出生即刻Apgar评分、男婴比例、阴道分娩率的差异均无统计学意义(P0.05)。与适宜增重GDM组相比,过度增重GDM组新生儿具有较高的平均出生体质量、较低的血糖水平,该组大于胎龄儿(LGA)比例增加,新生儿腹围/头围比(AC/HC)、体脂百分含量均显著增高(P0.01)。3GDM患者孕晚期体质量增速与GA、内脂素、HbA1c及新生儿出生体质量、新生儿体脂百分含量均呈显著正相关(r=0.524、0.470、0.456、0.329、0.473,P0.001)。结论:GA、内脂素水平的监测可能在评估GDM患者孕晚期体质量增长方面具有一定临床实用价值,而GDM患者孕晚期体质量增长过速则可能加速内脏脂肪积累、加重原有的糖脂代谢紊乱,并与新生儿出生体质量及体脂含量的增加密切相关。     

Body mass index: a true indicator of body fat in obese gravidas

OBJECTIVE: To determine the relationship between body mass index (BMI) and percent body fat in overweight/obese pregnant women (BMI >25) before and during pregnancy. STUDY DESIGN: Thirteen overweight women were evaluated longitudinally (prospective cohort study design) before conception, in early gestation (12-22 weeks) and in late gestation (31-36 weeks). BMI was calculated as weight (kg)/height (m)2, and percent body fat was estimated using hydrodensitometry with correction for residual lung volume. RESULTS: The correlation between BMI and percent body fat before conception was r2 = 0.86 (p = 0.001). Furthermore, the correlation remained strong in early pregnancy, r2 = 0.84 (p = 0.001), but was less strong yet significant, r2 = 0.54 (p = 0.004), in late gestation. CONCLUSION: In overweight women, the correlation between BMI and percent body fat remained significant during pregnancy. However, the correlation weakened as the pregnancy advanced.     

Subcutaneous fat in the fetal abdomen as a predictor of growth restriction.

OBJECTIVE: To determine if measuring fetal abdominal fat antenatally using ultrasound can predict fetal growth restriction (FGR). METHODS: One hundred thirty-seven unselected women with singleton pregnancies had serial ultrasound scans at 20, 26, 31, and 38 weeks' gestation. Subcutaneous fat in the fetal abdomen was measured using the same section as the abdominal circumference (AC). Outcome measures were birth weight, neonatal morbidity, and ponderal index. RESULTS: Infants with subcutaneous fat less than 5 mm at 38 weeks (n = 51) were almost five times more likely to have a birth weight below the 10th centile than those with subcutaneous fat of 5 mm or more (n = 75). The incidence of neonatal morbidity was significantly higher in infants with subcutaneous fat less than 5 mm, compared with those with subcutaneous fat of 5 mm or more (20% versus 8%, P < .05). Decreased subcutaneous fat was also associated with a high prevalence of low ponderal index, regardless of birth weight category. CONCLUSION: Measurement of fat in the abdominal wall is a simple technique with a sensitivity for predicting low birth weight similar to that of conventional sonography and might potentially predict FGR irrespective of fetal weight.