Donna L. Shannon

Maternal diabetes and neonatal macrosomia. II. Neonatal anthropometric measurements

Anthropometric measurements were obtained within 12 h of birth in 52 infants of non-diabetic mothers and 61 infants of diabetic mothers. Most of the diabetic patients were under good control, only ten of 61 having postpartum hemoglobin A1c levels in excess of normal. Neonates were grouped as normally-grown or macrosomic. Birthweight, crown-heel length, head circumference and skinfold thickness were measured. In each diabetes class, macrosomic neonates had larger mean length, head circumference and skinfold thickness than their normally-grown peers. At equal birthweight, neonates of gestational diabetic mothers and of non-diabetic mothers were similar in length, head circumference and skinfold thickness. Neonates of permanently insulin-requiring diabetics were similar to their non-diabetic peers in length and head circumference but had thicker skinfold thicknesses. Anthropometric measurements do not permit differentiation of the origin of neonatal macrosomia.

Dynamic skinfold thickness measurements: a noninvasive estimate of neonatal extracellular water content.

Summary: Application of a Harpenden caliper to a neonates skinfold results in an exponential decline of the skinfold thickness, stabilizing within 50–60 sec. In order to elucidate the meaning of this decline, simultaneous measurements of skinfold thickness (SFT, by Harpenden caliper connected to a chart recorder), corrected bromide space (CBS, in ml/kg), plasma volume (ml/kg, by T-1824 dilution) and interstitial water (IW, ml/kg = CBS-plasma volume) were obtained in 18 term and 18 preterm neonates. Skinfold thickness was measured at the midtricipital (MT) and subscapular (SS) sites. The magnitude of SFT decline was estimated as the difference between 0–60 sec readings expressed in % of 0 second reading (%ΔSFT). The rate of SFT decline was estimated as the slope of the semilogarithmic plot from 4–20 sec after caliper application (SΔSFT).The 36 neonates whose birthweights ranged from 620–3700 g and whose gestational ages ranged from 27–41 wk were studied within 12 h of birth. Mean CBS, IW, %ΔMT, %ΔSS, SΔMT and SΔSS were higher in preterm than in term neonates (P < 0.001). Mean plasma volume was higher in preterm neonates (P = 0.009), but the difference disappeared after exclusion of six polycythemic term neonates from the calculations. The magnitude of SFT decline correlated well with both CBS (%ΔMT versus CBS: r = 0.71 and %ΔSS versus CBS: r = 0.71) and IW (%ΔMT versus IW: r = 0.71 and %ΔSS versus IW: r = 0.70). The rate of decline correlated moderately but highly significantly with both CBS (SΔMT versus CBS: r = 0.50 and SΔSS versus CBS: r = 0.42) and IW (SΔMT versus IW: r = 0.51 and SΔSS versus IW: r = 0.43). Exculsion of five neonates less than 30 wk in gestation improved the correlations with both %ΔSFT and SΔSFT.These data suggest that the decline in SFT measurements after caliper application results from the expression of subcutaneous IW from the skinfold and that both the amount of water expressed and the rate of its expression increase linearly with the amount of extracellular and IW in the body.Speculation: Both the magnitude and the rate of skinfold thickness compressibility or expressibility appear to be intimately related to extracellular and interstitial water contents of the neonatal body. Dynamic skinfold thickness measurements may therefore be noninvasive estimates that are representative of body hydration and that may be used in research on neonatal body composition as well as clinically to evaluate hydration status of sick neonates.

Body water estimates in neonatal polycythemia.

To determine whether neonatal polycythemia and its treatment by partial exchange transfusion affect body water estimates, 10 normocythemic and eight polycythemic neonates were studied within 12 hours of birth. Total body water, extracellular water, and plasma volume were estimated immediately prior to and following exchange. Intracellular and interstitial water contents were calculated. There were no significant differences between normocythemic and preexchange polycythemic neonates in mean total body water, extracellular water, interstitial water, and intracellular water contents. In the polycythemic group, exchange did not affect mean total body water, but was associated with decreases in mean extracellular water and mean interstitial water and an increase in mean intracellular water. Mean transcapillary escape rate of T-1824 was not affected by exchange but was quite rapid both before (35 +/- SE 3%/hr) and after the procedure (30 +/- 4.9%/hr). These data suggest that moderate polycythemia in normal term neonates does not affect total and extravascular body water estimates, but that a fluid shift from the extracellular to the intracellular space may accompany the exchange procedure.

Maternal diabetes and neonatal macrosomia. III. Neonatal body water estimates

Body water estimates were obtained within 12 h of birth in 52 infants of non-diabetic mothers and 61 infants of diabetic mothers. Neonates were grouped as normally-grown or macrosomic. Total body water and extracellular water were estimated from antipyrine space and corrected bromide space, respectively. Intracellular water was assumed to be the difference between total and extracellular water. Infants of diabetic mothers, whether normally-grown or macrosomic, had markedly less mean total body water than normally-grown neonates of non-diabetic mothers. No effect of neonatal macrosomia or maternal diabetes on extracellular and intracellular water estimates could be detected with the techniques used. It is suggested that changes in total body water occur as a result of excessive fat accretion during fetal life.

Chemical Changes in Human Skeletal Muscle during Fetal Development

Skeletal muscle samples obtained from 6 nonmacerated stillborn fetuses and 18 liveborn neonates who died within 24 h of birth were analyzed. Gestational age ranged from 19 to 44 weeks. 17 neonates were normally grown (NG) and 7 were intrauterine growth retarded (IGR). Chemical components were expressed in milliliters or grams per 100 g of tissue. As gestation progressed, total water (TW) and extracellular water (ECW) contents decreased, intracellular water (ICW) content and nitrogen content remained stable, and intracellular/total water ratio (ICW/TW) increased. Fat content was negligible throughout gestation. Compared to their NG peers, IGR neonates had muscle with decreased ECW and increased ICW/TX, whereas TW, ICW and nitrogen contents were similar. These preliminary data provide a basis for further studies of muscle composition and for discussion of existing hypotheses on the effect of fetal growth retardation upon body composition.

Fingernail Nitrogen Content in Infants of Diabetic Mothers and in Macrosomic Neonates

Fingernail nitrogen content (FNC) was determined on nail trimmings obtained within 24 h of birth from 21 infants of diabetic mothers and 82 infants of nondiabetic mothers. Macrosomic infants of nondia

ABSENCE OF PHOSPHATIDYLGLYCEROL IN AMNIOTIC FLUID OF BABOONS AT TERM

89 samples of amniotic fluid were obtained from 46 pregnant baboons at 91 to 176 days of gestation (term = 180 days). In 8 baboons delivered by cesarean section at 174-176 days of gestation, the entire amniotic fluid contents of the uterus were aspirated and lung lavage was performed within 1 hour of birth. Surfactant was purified from these 8 amniotic fluids and products of lung lavage by differential and density-gradient centrifugation. Lecithin/sphingomyelin ratios ranged from 0 to 2.41. Mean (±SD) L/S ratio at term was significantly higher than before term (0.77±0.55 vs 0.28±0.25, p<0.001). Of 12 samples obtained after 170 days of pregnancy, only 6 had L/S ratios greater than 1 and only 1 had a ratio in excess of 2. The relation between L/S ratios and gestational maturity was best described as a second order polynomial (r=0.63, p<0.001). Phosphatidylglycerol (PG) was detected in none of the amniotic fluid samples. Of the 8 surfactants purified from amniotic fluid at term, none contained detectable amounts of PG. Yet, 6 of 7 surfactants purified from products of lung lavage did contain PG. These data suggest 3 possibilities: (1) baboon fetuses make no PG; (2) PG is present in amniotic fluid, but in concentrations too low to be detected; or (3) PG is present in the lungs but is not excreted into amniotic fluid. The third explanation appears to be most likely.

Absence of phosphatidylglycerol in amniotic fluid of baboons at term

bones. Well-formed cartilage and osseous tissue were easily identified, but the soft tissue was largely resorbed with only ghosts of cells and degenerative changes present. Chorionic villi and trophoblast were not identified in the tissue, which suggested complete resorption of the placental component. Although the gestational age of this ectopic mass is difficult to determine, the extensive ossification indicates that it had progressed to at least 12 weeks before silently aborting. The time of the occurrence of the ectopic pregnancy is not known although the histologic changes suggest a process that occurred over months or years. The operative findings of the small cystic right tuboovarian mass at tubal ligation 4 years previously may have been due to the ectopic pregnancy. In addition, the 2-yeal histology of chronic pain in the right lower quadrant may have been due in part to the ectopic gestation. Differential diagnoses of cartilage and bone within a fallopian tube include dystrophic calcification, heterotopic bone formation, and teratomas in addition to retained ectopic products of conception. In this case the cartilaginous and osseous tissue had the structure and shape of fetal bones, which indicated the presence of a prior ectopic gestation.

Maternal diabetes and neonatal macrosomia: I. Postpartum maternal hemoglobin A 1c levels and neonatal hypoglycemia

Hemoglobin A1c (HgbA1c) levels were determined within 24 hours after delivery in 88 nondiabetic and 73 diabetic women belonging to Whites classes A to D. Diet-controlled gestational diabetic women had mean (+/- SE) Hgb A1c levels similar to those of nondiabetics (5.8 +/- 0.18% vs 5.7 +/- 0.08%). Mean Hgb A1c levels were higher in insulin-requiring gestational (6.4 +/- 0.20%, P less than .05) and permanent (6.5 +/- 0.27%, P less than .05) diabetics than in nondiabetics. The proportions of subjects with levels above the normal range were also larger in the insulin-requiring groups. Mean Hgb A1c levels and the proportions of abnormally high levels were similar for mothers of macrosomic and of normally grown neonates in the nondiabetic as well as in the various diabetes groups. There was no correlation between maternal Hgb A1c level and neonatal birth weight, either real or relative. There were also no statistically significant differences in mean Hgb A1c levels between mothers of neonates with or without hypoglycemia within four hours of birth. Hgb A1c measurement did not permit differentiation between those mothers of macrosomic neonates who were diabetic and those who were not. In conclusion, although Hgb A1c level has been shown to reflect diabetic control, our data suggest that it may not be reliable as an indicator of fine tuning during the third trimester of pregnancy or as a predictor of the effects of diabetes on the fetus.

1326 PLASMA LIPIDS IN NEONATES RECEIVING FAT EMULSIONS

Plasma total lipids (TL), free fatty acids (FFA), triglycerides (TG) and free glycerol (FG) were measured in 11 normally grown premature neonates who received total parenteral nutrition with dextrose, amino acids and fat emulsion. Gestational ages ranged from 26 to 32 weeks, birthweights ranged from 964 to 1758g and postnatal ages ranged from 2 to 14 days. Fat emulsion was infused continuously, beginning with a daily dose of 1 g/kg on the first day and increasing by 1 g/kg each 24 hours to a daily dose of 4 g/kg. Blood samples were obtained before and 4, 8, 12 and 24 hours after each dosage change. For all lipid fractions measured the mean (±SE) concentrations increased over mean preinfusion values, differences reaching statistical significance (p<0.05) at 12 hours for TL (413±16.0 vs 327±21.3 mg/dl), at 8 hours for FFA (16.2±1.78 vs 10.6±1.19 mEq/dl), at 12 hours for FG (0.26±0.093 vs 0.16±0.030 mM/dl) and at 4 hours for TG (0.51±0.103 vs 0.30±0.031 mM/dl). The mean concentrations of all lipid fractions remained higher than their respective baselines and there was no significant change in the mean values for any particular fraction. These data suggest that the infusion of fat emulsion at 1 g/kg produces elevations of all plasma lipids but that the effects of 4 g/kg do not markedly differ from those of 1 g/kg. The tolerance of individual patients, however, varies considerably at daily dosage in excess of 2 g/kg. Studies to determine the optimal dosage of fat emulsions in small premature neonates are needed.