Maternal obesity does not influence human milk protein 15N natural isotope abundance.

Obesity increases protein metabolism with a potential effect on nitrogen isotope fractionation. The aim of this study was to test the influence of obesity on human milk extracted protein 15N natural isotope abundance (NIA) at one month post-partum and to compare human milk extracted protein 15N NIA and bulk infant hair 15N NIA. This cross-sectional observational study involved 16 obese mothers (body mass index (BMI) ≥ 30 kg m-2 before pregnancy) matched with 16 normal-weight mothers (18.5 kg m-2 ≤ BMI < 25 kg m-2) for age and pregnancy characteristics. Human milk extracted protein and bulk infant hair 15N NIA were determined by isotope ratio monitoring by mass spectrometry interfaced to an elemental analyser (IRM-EA/MS). No significant difference was found in human milk protein 15N NIA values between obese and normal-weight mothers (8.93 ± 0.48 ‰ vs. 8.95 ± 0.27 ‰). However, human milk protein 15N NIA was significantly lower than bulk infant hair 15N NIA: 8.94 ± 0.38 ‰ vs. 9.66 ± 0.69 ‰, respectively. On the basis of these results, it is concluded that human milk protein 15N NIA measured at one month post-partum is not influenced by maternal obesity. These findings suggest that 15N NIA may be exploited to study metabolism without considering maternal obesity as a confounder.

Higher Leptin but Not Human Milk Macronutrient Concentration Distinguishes Normal-Weight from Obese Mothers at 1-Month Postpartum.

INTRODUCTION: Exclusively breastfed infants born to obese mothers have previously been shown to gain less weight by 1-month postpartum than infants of normal-weight mothers. Our hypothesis is that human milk composition and volume may differ between obese and normal-weight mothers. OBJECTIVE: To compare human milk leptin, macronutrient concentration, and volume in obese and normal-weight mothers. Mother and infant characteristics were studied as secondary aims. MATERIALS AND METHODS: This cross-sectional observational study compared 50 obese mothers matched for age, parity, ethnic origin, and educational level with 50 normal-weight mothers. Leptin, macronutrient human milk concentration, and milk volume were determined at 1 month in exclusively breastfed infants. Mother characteristics and infant growth were recorded. RESULTS: Human milk leptin concentration was higher in obese mothers than normal-weight mothers (4.8±2.7 vs. 2.5±1.5 ng.mL-1, p<0.001). No difference was observed between obese and normal-weight mothers in protein, lipid, carbohydrate content, and volume, nor in infant weight gain. CONCLUSION: Leptin concentration was higher in the milk of obese mothers than that of normal-weight mothers, but macronutrient concentration was not. It remains to be established whether the higher leptin content impacts on infant growth beyond the 1-month of the study period.

Decreased full breastfeeding, altered practices, perceptions, and infant weight change of prepregnant obese women: a need for extra support.

OBJECTIVE: The purpose of this work was to compare breastfeeding practices, perceptions, and infant weight change of prepregnant obese versus normal-weight mothers in the first 3 months postpartum. PATIENTS AND METHODS: For the prospective case-control study, obese mothers (prepregnant BMI > or = 30 kg/m(2)) were matched with normal-weight mothers (18.5 < or = prepregnant BMI < 25 kg/m(2)) according to initial infant feeding, parity, maternal age, ethnicity, and education. Participants completed an oral questionnaire in the hospital and a telephone interview at 1 and 3 months postpartum. RESULTS: Of 1432 mothers who had given birth at a university hospital in France, 10% were obese. Breastfeeding initiation was lower for obese (48%) versus normal-weight (64%) mothers. A total of 111 of 141 obese mothers were paired with 111 normal-weight mothers. Infant birth weight was similar for newborns of obese and normal-weight mothers. Among mothers who initiated breastfeeding, infant weight gain from 0 to 1 month was lower in breastfed infants of obese mothers compared to normal-weight mothers. Obese mothers were less likely to maintain full breastfeeding at 1 month and 3 months. The percentage of mothers breastfeeding to any extent did not differ between obese and reference women. Obese mothers more often felt uncomfortable breastfeeding in public at 3 months. Fewer obese mothers perceived that their milk supply was sufficient at 1 month and 3 months. Despite greater breastfeeding difficulties, obese mothers were less likely to seek support for breastfeeding in the first 3 months postpartum. CONCLUSIONS: Pediatricians and health professionals should recognize that obese mothers have different breastfeeding practices and perceptions. Extra support and intervention are needed among obese mothers during prenatal and early postnatal periods so that their children can benefit from breastfeeding.

Functional characterization of GATA3 mutations causing the hypoparathyroidism-deafness-renal (HDR) dysplasia syndrome: insight into mechanisms of DNA binding by the GATA3 transcription factor.

The hypoparathyroidism-deafness-renal (HDR) dysplasia syndrome is an autosomal dominant disorder caused by mutations of the dual zinc finger transcription factor, GATA3. We investigated 21 HDR probands and 14 patients with isolated hypoparathyroidism for GATA3 abnormalities. Thirteen different heterozygous germline mutations were identified in patients with HDR. These consisted of three nonsense mutations, six frameshifting deletions, two frameshifting insertions, one missense (Leu348Arg) mutation and one acceptor splice site mutation. The splice site mutation was demonstrated to cause a pre-mRNA processing abnormality leading to the use of an alternative acceptor site 8 bp downstream of the normal site, resulting in a frameshift and prematurely terminated protein. Electrophoretic mobility shift assays (EMSAs) revealed three classes of GATA3 mutations: those that lead to a loss of DNA binding which represent over 90% of all mutations, and involved a loss of the carboxy-terminal zinc finger; those that resulted in a reduced DNA-binding affinity; and those (e.g. Leu348Arg) that did not alter DNA binding or the affinity but likely altered the conformational change that occurs during binding in the DNA major groove as predicted by a three-dimensional modeling. These results elucidate further the molecular mechanisms underlying the altered functions of mutants of this zinc finger transcription factor and their role in causing this developmental anomaly. No mutations were identified in patients with isolated hypoparathyroidism, thereby indicating that GATA3 abnormalities are more likely to result in two or more of the phenotypic features of the HDR syndrome and not in one, such as isolated hypoparathyroidism.