Impact of maternal metabolic abnormalities in pregnancy on human milk and subsequent infant metabolic development: methodology and design

Associations of Metabolic and Obstetric Risk Parameters with Timing of Lactogenesis II

Lactogenesis II is the onset of copious milk production following parturition. Delayed onset of lactogenesis II (DLII) often contributes to poorer lactation performance, which may adversely affect maternal and child health. The present study aims to identify the metabolic and obstetric risk factors for DLII in a secondary analysis of a prospective cohort study following pregnant women through postpartum. We defined the onset of lactogenesis II as delayed if it occurred ≥72 h postpartum. Multiple logistic regression analyses were conducted to evaluate the associations of metabolic and obstetric variables with DLII. Median onset of lactogenesis II was 72.4 h (IQR 60.4–91.6) postpartum, and 55.4% (98 of 177) of women experienced DLII. Time to first breast contact ≥ 2 h postpartum compared to ≤1 h postpartum was associated with DLII (OR 2.71 95% CI 1.12–6.53) with adjustment for age, race, pregravid BMI, primiparity, and mode of delivery, while metabolic variables were not significantly associated with DLII. In this comprehensive examination of potential metabolic and obstetric parameters, earlier timing of putting the infant to the breast remained significantly associated with earlier onset of milk coming in after consideration of the other potential risk factors. Obstetrical practices, including putting the baby to the breast later, may have an important impact on the timing of lactation, and interventions are needed to address this concern.

Oligosaccharides and Microbiota in Human Milk Are Interrelated at 3 Months Postpartum in a Cohort of Women with a High Prevalence of Gestational Impaired Glucose Tolerance

BACKGROUND

Human milk is a rich source of human milk oligosaccharides (HMOs) and bacteria. It is unclear how these components interact within the breast microenvironment.

OBJECTIVES

The objectives were first, to investigate the association between maternal characteristics and HMOs, and second, to assess the association between HMOs and microbial community composition and predicted function in milk from women with high rates of gestational glucose intolerance.

METHODS

This was an exploratory analysis of a previously completed prospective cohort study (NCT01405547) where milk samples (n = 107) were collected at 3 mo postpartum. Milk microbiota composition was analyzed by V4-16S ribosomal RNA gene sequencing and HMOs by rapid high-throughput HPLC. Data were stratified and analyzed by maternal secretor status phenotype and associations between HMOs and microbiota were determined using linear regression models (ɑ-diversity), Adonis (B-diversity), Poisson regression models (differential abundance), and general linear models (predicted microbial function).

RESULTS

Prepregnancy BMI, race, and frequency of direct breastfeeding, but not gestational glucose intolerance, were found to be significantly associated with a number of HMOs among secretors and non-secretors. Fucosyllacto-N-hexaose was negatively associated with microbial richness (Chao1) among secretors [B-estimate (SE): -9.3 × 102 (3.4 × 102); P = 0.0082] and difucosyllacto-N-hexaose was negatively associated with microbiota diversity (Shannon index) [-1.7 (0.78); P = 0.029] among secretors. Lacto-N-neotetraose (LNnT) was associated with both microbial B-diversity (weighted UniFrac R2 = 0.040, P = 0.036) and KEGG ortholog B-diversity (Bray-Curtis R2 = 0.039, P = 0.043) in secretors. Additionally, difucosyllactose in secretors and disialyllacto-N-hexaose and LNnT in non-secretors were associated with enrichment of predicted microbial genes encoding for metabolism- and infection-related pathways (P-false discovery rate < 0.1).

CONCLUSIONS

HMOs are associated with the microbial composition and predicted microbial functions in human milk at 3 mo postpartum. Further research is needed to investigate the role these relations play in maternal and infant health.

Maternal Diet and Infant Feeding Practices Are Associated with Variation in the Human Milk Microbiota at 3 Months Postpartum in a Cohort of Women with High Rates of Gestational Glucose Intolerance

BACKGROUND

Human milk contains a diverse community of bacteria believed to play a role in breast health and inoculation of the infant's gastrointestinal tract. The role of maternal nutrition and infant feeding practices on the human milk microbiota remains poorly understood.

OBJECTIVE

Our aim was to explore the associations between maternal diet (delivery to 3 mo postpartum), infant feeding practices, and the microbial composition and predicted function in milk from women with varied metabolic status.

METHODS

This was an exploratory analysis of a previously completed prospective cohort study of women with varying degrees of gestational glucose intolerance (NCT01405547). Milk samples (n = 93 mothers) were collected at 3 mo postpartum. Maternal dietary information (validated food-frequency questionnaire) and infant feeding practices (human milk exclusivity, frequency of direct breastfeeding per day) were collected. V4-16S ribosomal RNA gene sequencing (Illumina MiSeq) was conducted to determine microbiota composition.

RESULTS

Intake of polyunsaturated fat [β estimate (SE): 0.036 (0.018), P = 0.047] and fiber from grains [0.027 (0.013), P = 0.048] were positively associated with ɑ-diversity (Shannon index) of human milk. Overall microbial composition of human milk clustered based on human milk exclusivity (weighted UniFrac R2 = 0.034, P = 0.015; Bray-Curtis R2 = 0.041, P = 0.007), frequency of direct breastfeeding per day (Bray-Curtis R2 = 0.057, P = 0.026), and maternal fiber intake from grains (Bray-Curtis R2 = 0.055, P = 0.040). Total fiber, fiber from grains, dietary fat, and infant feeding practices were also associated with a number of differentially abundant taxa. The overall composition of predicted microbial functions was associated with total fiber consumption (Bray-Curtis R2 = 0.067, P = 0.036) and human milk exclusivity (Bray-Curtis R2 = 0.041, P = 0.013).

CONCLUSIONS

Maternal consumption of fiber and fat, as well as mother's infant feeding practices, are important determinants of the human milk microbiota. Understanding whether these microbial changes impact an infant's overall health and development requires future study.

Examining the relationship between maternal body size, gestational glucose tolerance status, mode of delivery and ethnicity on human milk microbiota at three months post-partum

BACKGROUND

Few studies have examined how maternal body mass index (BMI), mode of delivery and ethnicity affect the microbial composition of human milk and none have examined associations with maternal metabolic status. Given the high prevalence of maternal adiposity and impaired glucose metabolism, we systematically investigated the associations between these maternal factors in women ≥20 years and milk microbial composition and predicted functionality by V4-16S ribosomal RNA gene sequencing (NCT01405547;  https://clinicaltrials.gov/ct2/show/NCT01405547 ). Demographic data, weight, height, and a 3-h oral glucose tolerance test were gathered at 30 (95% CI: 25-33) weeks gestation, and milk samples were collected at 3 months post-partum (n = 113).

RESULTS

Multivariable linear regression analyses demonstrated no significant associations between maternal characteristics (maternal BMI [pre-pregnancy, 3 months post-partum], glucose tolerance, mode of delivery and ethnicity) and milk microbiota alpha-diversity; however, pre-pregnancy BMI was associated with human milk microbiota beta-diversity (Bray-Curtis R² = 0.037). Women with a pre-pregnancy BMI > 30 kg/m² (obese) had a greater incidence of Bacteroidetes (incidence rate ratio [IRR]: 3.70 [95% CI: 1.61-8.48]) and a reduced incidence of Proteobacteria (0.62 [0.43-0.90]) in their milk, compared to women with an overweight BMI (25.0-29.9 kg/m²) as assessed by multivariable Poisson regression. An increased incidence of Gemella was observed among mothers with gestational diabetes who had an overweight BMI versus healthy range BMI (5.96 [1.85-19.21]). An increased incidence of Gemella was also observed among mothers with impaired glucose tolerance with an obese BMI versus mothers with a healthy range BMI (4.04 [1.63-10.01]). An increased incidence of Brevundimonas (16.70 [5.99-46.57]) was found in the milk of women who underwent an unscheduled C-section versus vaginal delivery. Lastly, functional gene inference demonstrated that pre-pregnancy obesity was associated with an increased abundance of genes encoding for the biosynthesis of secondary metabolites pathway in milk (coefficient = 0.0024, P_FDR < 0.1).

CONCLUSIONS

Human milk has a diverse microbiota of which its diversity and differential abundance appear associated with maternal BMI, glucose tolerance status, mode of delivery, and ethnicity. Further research is warranted to determine whether this variability in the milk microbiota impacts colonization of the infant gut.

Could a remarkable decrease in leptin and insulin levels from colostrum to mature milk contribute to early growth catch-up of SGA infants?

BACKGROUND

Breast milk is known to contain many bioactive hormones and peptides, which can influence infant growth and development. In this context, the purpose of this study was to evaluate the influence of different clinical pregnancy conditions on hormone concentrations in colostrum and mature breast milk.

METHODS

An observational study was performed with mother-newborn pairs divided into five groups according to maternal clinical background: diabetes (12), hypertension (5), smoking (19), intrauterine growth restriction of unknown causes with small-for-gestational-age newborns at delivery (12), and controls (21). Socioeconomic data, anthropometric measurements and breast milk samples were collected between the first 24 and 48 h and 30 days postpartum. Leptin, adiponectin, and insulin levels in breast milk were measured by immunoassays.

RESULTS

A significant decrease in leptin (p = 0.050) and insulin (p = 0.012) levels from colostrum to mature breast milk in mothers of small-for-gestational-age infants was observed. Maternal body mass index was correlated with both leptin and insulin, but not with adiponectin. Insulin levels were negatively correlated to infant weight gain from birth to one month (p = 0.050). In addition, catch-up growth was verified for small-for-gestational-age infants throughout the first month of life.

CONCLUSIONS

This study suggests that a remarkable decrease in leptin and insulin levels in mature milk of mothers of small-for-gestational-age newborns may be involved in the rapid weight gain of these newborns. The physiological and external mechanisms by which these significant decreases and rapid weight gains occur in this group remain to be elucidated.

Impact of Metabolic Hormones Secreted in Human Breast Milk on Nutritional Programming in Childhood Obesity

Obesity is the most common metabolic disease whose prevalence is increasing worldwide. This condition is considered a serious public health problem due to associated comorbidities such as diabetes mellitus and hypertension. Perinatal morbidity related to obesity does not end with birth; this continues affecting the mother/infant binomial and could negatively impact on metabolism during early infant nutrition. Nutrition in early stages of growth may be essential in the development of obesity in adulthood, supporting the concept of "nutritional programming". For this reason, breastfeeding may play an important role in this programming. Breast milk is the most recommended feeding for the newborn due to the provided benefits such as protection against obesity and diabetes. Health benefits are based on milk components such as bioactive molecules, specifically hormones involved in the regulation of food intake. Identification of these molecules has increased in recent years but its action has not been fully clarified. Hormones such as leptin, insulin, ghrelin, adiponectin, resistin, obestatin and insulin-like growth factor-1 copeptin, apelin, and nesfatin, among others, have been identified in the milk of normal-weight women and may influence the energy balance because they can activate orexigenic or anorexigenic pathways depending on energy requirements and body stores. It is important to emphasize that, although the number of biomolecules identified in milk involved in regulating food intake has increased considerably, there is a lack of studies aimed at elucidating the effect these hormones may have on metabolism and development of the newborn. Therefore, we present a state-of-the-art review regarding bioactive compounds such as hormones secreted in breast milk and their possible impact on nutritional programming in the infant, analyzing their functions in appetite regulation.

Influence of breastfeeding during the postpartum oral glucose tolerance test on plasma glucose and insulin

OBJECTIVE

To examine the effect of breastfeeding during the postpartum oral glucose tolerance test (OGTT) on maternal blood glucose and insulin among women with recent gestational diabetes mellitus.

METHODS

Participants were enrolled in the Study of Women, Infant Feeding, and Type 2 Diabetes, a prospective observational cohort study of 1,035 Kaiser Permanente Northern California members who had been diagnosed with GDM and subsequently underwent a 2-hour 75-g OGTT at 6-9 weeks postpartum for the study enrollment examinations from 2008 to 2011. For this analysis, we selected 835 study participants who reported any intensity of lactation and were observed either breastfeeding their infants (ie, putting the infant to the breast) or not breastfeeding during the OGTT.

RESULTS

Of 835 lactating women, 205 (25%) breastfed their infants during the 2-hour 75-g OGTT at 6-9 weeks postpartum. Mean (standard deviation) duration of breastfeeding during the OGTT was 15.3 (8.1) minutes. Compared with not having breastfed during the OGTT, having breastfed during the test was associated with lower adjusted mean (95% confidence interval) 2-hour glucose (mg/dL) by -6.2 (-11.5 to -1.0; P=.02), 2-hour insulin (microunits/mL) by -15.1 (-26.8 to -3.5; P=.01), and natural log 2-hour insulin by -0.15 (-0.25 to -0.06; P<.01), and with higher insulin sensitivity index0,120 by 0.08 (0.02-0.15; P=.02), but no differences in plasma fasting glucose or insulin concentrations.

CONCLUSION

Among postpartum women with recent gestational diabetes mellitus, breastfeeding an infant during the 2-hour 75-g OGTT may modestly lower plasma 2-hour glucose (5% lower on average) as well as insulin concentrations in response to ingestion of glucose.

Associations of prenatal metabolic abnormalities with insulin and adiponectin concentrations in human milk

BACKGROUND

Emerging evidence indicates that metabolic hormones are present in human milk, but, to our knowledge, no studies have investigated the impact of maternal metabolic status assessed during pregnancy on insulin and adiponectin concentrations in milk.

OBJECTIVES

We aimed to investigate the associations of prenatal metabolic abnormalities with insulin and adiponectin in human milk and to compare the concentrations of these hormones in early and mature milk.

DESIGN

Pregnant women aged ≥20 y with intention to breastfeed and without preexisting type 1 or 2 diabetes were recruited. Participants (n = 170) underwent a 3-h oral-glucose-tolerance test at 30 wk (95% CI: 25, 33 wk) gestation and donated early (the first week postpartum) and mature (3 mo postpartum) milk.

RESULTS

Adiponectin and insulin concentrations in early milk were higher than those in mature milk (both P < 0.0001). Prenatal metabolic abnormalities, including higher pregravid BMI (β ± SEE: 0.053 ± 0.014; P = 0.0003) and gravid hyperglycemia (0.218 ± 0.087; P = 0.01), insulin resistance (0.255 ± 0.047; P < 0.0001), lower insulin sensitivity (-0.521 ± 0.108; P < 0.0001), and higher serum adiponectin (0.116 ± 0.029; P < 0.0001), were associated with higher insulin in mature milk after covariate adjustment. Prenatal metabolic measures were not associated with milk adiponectin, but obstetrical measures that included nulliparity (0.171 ± 0.058; P = 0.004), longer duration of gestation (0.546 ± 0.146; P = 0.0002), and unscheduled cesarean delivery (0.387 ± 0.162; P = 0.02) were associated with higher adiponectin in early milk after covariate adjustment, including the time elapsed from delivery to milk collection.

CONCLUSION

Maternal prenatal metabolic abnormalities are associated with high insulin concentrations in mature milk, whereas only obstetrical variables are associated with adiponectin concentrations in early milk.

Effect of macronutrient intake during the second trimester on glucose metabolism later in pregnancy

BACKGROUND

Dietary intake is known to influence glucose metabolism, but there is little consensus on the optimal distribution of macronutrient intakes during pregnancy to prevent gestational diabetes (GDM).

OBJECTIVE

We aimed to investigate whether macronutrient intake distribution during the second trimester of pregnancy was associated with glucose metabolism later in pregnancy.

DESIGN

Women with singleton pregnancies and without preexisting type 1 or type 2 diabetes were included. Participants underwent a 3-h oral-glucose-tolerance test at 30 wk (95% CI: 25, 33 wk) gestation and were asked to recall their second-trimester dietary intake by using a validated food-frequency questionnaire.

RESULTS

Of the 205 participants, 47 (22.9%) had a diagnosis of GDM. A higher intake of saturated fat (β ± SEE: 0.059 ± 0.021; P = 0.005) and trans fat (0.381 ± 0.145; P = 0.009) as a percentage of energy and of added sugar (0.017 ± 0.007; P = 0.02) and a lower intake of vegetable and fruit fiber (-0.026 ± 0.012; P = 0.03) were individually associated with increased fasting glucose after multiple adjustment. In participants with a family history of type 2 diabetes, a higher vegetable and fruit fiber intake was associated with reduced insulin resistance (-0.100 ± 0.029; P = 0.0008) and increased insulin sensitivity (0.029 ± 0.012; P = 0.01), after similar adjustment. An increased risk (OR per 1-SD change) of GDM was associated with lower carbohydrate (0.60; 95% CI: 0.40, 0.90) and higher total fat (1.61; 95% CI: 1.06, 2.44) intakes as a percentage of energy, after similar adjustment.

CONCLUSIONS

Macronutrient intake during the second trimester of pregnancy was associated with a risk of abnormal glucose metabolism later in pregnancy. This finding supports the need for continued work to determine optimal prenatal nutritional strategies to prevent GDM. This trial is registered at clinicaltrials.gov as NCT01405547.