Obesity as a risk factor for failure to initiate and sustain lactation

Mother's Own Milk Biomarkers Predict Coming to Volume in Pump-Dependent Mothers of Preterm Infants

OBJECTIVE

To assess serial secretory activation biomarker concentrations (sodium [Na], potassium [K], Na:K, protein, lactose, and citrate) in mother's own milk (MOM) from breast pump-dependent mothers of preterm infants to determine associations with coming to volume (CTV), defined as producing at least 500 mL/day MOM by day 14 postpartum.

STUDY DESIGN

We collected serial MOM samples and pumped MOM volume data for 14 days postpartum in mothers who delivered at <33 weeks of gestation. Regression models and the Mann-Whitney U test were used to evaluate associations.

RESULTS

Among 40 mothers, 39 (mean gestational age, 28.8 weeks; 67% overweight/obese; 59% nonwhite) had paired MOM volume and biomarker data; 33% achieved CTV between postpartum days 6 and 14. In univariate models, MOM Na on postpartum day 5 and Na:K on days 3 and 5 were associated with CTV. Mothers achieving CTV were more likely to have postpartum Na:K ≤1 on day 3 (75% vs 25%; P = .06) and ≤0.8 on day 5 (69% vs 10%; P < .01). In a multivariable regression model, day 5 Na:K (1 unit decrease in Na:K: OR, 18.7; 95% CI, 1.13-311.41; P = .049) and maternal prepregnancy body mass index (BMI) (1 unit increase in BMI: OR, 0.88; 95% CI, 0.78-0.99; P = .04) were associated with CTV between postpartum days 6 and 14.

CONCLUSIONS

Secretory activation and CTV were compromised in breast pump-dependent mothers with preterm delivery. CTV was predicted by MOM Na level and Na:K. These biomarkers have potential as objective point-of-care measures to detect potentially modifiable lactation problems in a high-risk population.

Prolactin - a pleiotropic factor in health and disease

The principal role of prolactin in mammals is the regulation of lactation. Prolactin is a hormone that is mainly synthesized and secreted by lactotroph cells in the anterior pituitary gland. Prolactin signalling occurs via a unique transmembrane prolactin receptor (PRL-R). The structure of the PRL-R has now been elucidated and is similar to that of many biologically fundamental receptors of the class 1 haematopoietic cytokine receptor family such as the growth hormone receptor. The PRL-R is expressed in a wide array of tissues, and a growing number of biological processes continue to be attributed to prolactin. In this Review, we focus on the newly discovered roles of prolactin in human health and disease, particularly its involvement in metabolic homeostasis including body weight control, adipose tissue, skin and hair follicles, pancreas, bone, the adrenal response to stress, the control of lactotroph cell homeostasis and maternal behaviour. New data concerning the pathological states of hypoprolactinaemia and hyperprolactinaemia will also be presented and discussed.

Hospital breastfeeding support and exclusive breastfeeding by maternal prepregnancy body mass index

Overweight and obese mothers in the United States have disproportionately lower rates of exclusive breastfeeding than mothers of normal weight. The Ten Steps to Successful Breastfeeding (Ten Steps), a series of evidence-based practices designed to support breastfeeding initiation, duration, and exclusivity, demonstrate effectiveness at the population level. It is unknown, however, whether they are consistently provided to women across all maternal body mass index (BMI) categories. We sought to determine whether pre-pregnancy BMI is associated with the implementation and effectiveness of the Ten Steps. We used data from Listening to Mothers III, a cross-sectional survey administered to a sample of mothers who delivered in U.S. hospitals between July 2011 and June 2012. Measures of the Ten Steps were based on maternal self-report on Listening to Mothers III. Our analytic sample was limited to mothers of term infants intending to breastfeed (N = 1,506, weighted). We conducted chi-square testing and constructed weighted multivariable logistic regression models to account for potential confounders. Results suggest that two practices (i.e., holding their babies skin-to-skin for the first time and being encouraged to breastfeed on demand) were more strongly associated with exclusive breastfeeding among mothers with obesity than other mothers. Additionally, mothers with obesity reported holding babies skin-to-skin significantly less often than other mothers. Thus, interventions aimed at helping mothers with obesity to hold their babies skin-to-skin in the first hour and teaching them to breastfeed on demand have the potential to decrease the breastfeeding disparities in this population.

Obese Mothers have Lower Odds of Experiencing Pro-breastfeeding Hospital Practices than Mothers of Normal Weight: CDC Pregnancy Risk Assessment Monitoring System (PRAMS), 2004-2008

OBJECTIVES

This study examines the extent to which a mother's pre-pregnancy body mass index (BMI) category is associated with her exposure to pro-breastfeeding hospital practices.

METHODS

Data from the 2004-2008 CDC PRAMS were analyzed for three states (Illinois, Maine, and Vermont) that had administered an optional survey question about hospital pro-breastfeeding practices.

RESULTS

Of 19,145 mothers surveyed, 19 % were obese (pre-pregnancy BMI ≥ 30). Obese mothers had lower odds than mothers of normal weight of initiating breastfeeding [70 vs. 79 % (unweighted), p < 0.0001]. Compared with women of normal weight, obese mothers had lower odds of being exposed to pro-breastfeeding hospital practices during the birth hospitalization. Specifically, obese mothers had higher odds of using a pacifier in the hospital [odds ratio (OR) 1.31, 95 % confidence interval (CI) (1.17-1.48), p < 0.0001] and lower odds of: a staff member providing them with information about breastfeeding [OR 0.71, 95 % CI (0.57-0.89), p = 0.002], a staff member helping them breastfeed [OR 0.69, 95 % CI (0.61-0.78), p < 0.0001], breastfeeding in the first hour after delivery [OR 0.55, 95 % CI (0.49-0.62), p < 0.0001], being given a telephone number for breastfeeding help [OR 0.65, 95 % CI (0.57-0.74), p < 0.0001], rooming in [OR 0.84, 95 % CI (0.73-0.97), p = 0.02], and being instructed to breastfeed on demand [OR 0.66, 95 % CI (0.58-0.75), p < 0.0001]. Adjusting for multiple covariates, all associations except rooming in remained significant.

CONCLUSIONS

Obesity stigma may be a determinant of breastfeeding outcomes for obese mothers. Breastfeeding support should be improved for this at-risk population.

Physiological mechanisms, behavioral and psychological factors influencing the transfer of milk from mothers to their young

This article is part of a Special Issue "Parental Care".Producing milk to support the growth of their young is a central element of maternal care in mammals. In spite of the facts that ecological constraints influence nursing frequency, length of time until weaning and the composition of milk, there is considerable similarity in the anatomy and physiology of milk production and delivery across mammalian species. Here we provide an overview of cross species variation in nursing patterns and milk composition as well as the mechanisms underlying mammary gland development, milk production and letdown. Not all women breastfeed their infants, thus in later sections we review studies of factors that facilitate or impede the initiation and duration of breastfeeding. The results of these investigations suggest that the decisions to initiate and maintain breastfeeding are influenced by an array of personal, social and biological factors. Finally, studies comparing the development of breastfed and formula fed infants as well as those investigating associations between breastfeeding, maternal health and mother/infant interaction are reviewed. Leading health agencies including the World Health Organization and CDC advocate breastfeeding for at least the first 6months postpartum. To achieve these rates will require not only institutional support but also a focus on individual mother/infant dyads and their experience.

Impact of breast-feeding and high- and low-protein formula on the metabolism and growth of infants from overweight and obese mothers

BACKGROUND

The combination of maternal obesity in early pregnancy and high protein intake in infant formula feeding might predispose to obesity risk in later life.

METHODS

This study assesses the impact of breast- or formula-feeding (differing in protein content by 1.65 or 2.7 g/100 kcal) on the metabolism of term infants from overweight and obese mothers. From birth to 3 mo of age, infants received exclusively either breast- or starter formula-feeding and until 6 mo, exclusively either a formula designed for this study or breast-feeding. From 6 to 12 mo, infants received complementary weaning food. Metabonomics was conducted on the infants' urine and stool samples collected at the age of 3, 6, and 12 mo.

RESULTS

Infant formula-feeding resulted in higher protein-derived short-chain fatty acids and amino acids in stools. Urine metabonomics revealed a relationship between bacterial processing of dietary proteins and host protein metabolism stimulated with increasing protein content in the formula. Moreover, formula-fed infants were metabolically different from breast-fed infants, at the level of lipid and energy metabolism (carnitines, ketone bodies, and Krebs cycle).

CONCLUSION

Noninvasive urine and stool metabolic monitoring of responses to early nutrition provides relevant readouts to assess nutritional requirements for infants' growth.

Breastfeeding initiation in the context of a home intervention to promote better birth outcomes

OBJECTIVE

This secondary analysis examined breastfeeding initiation rates and factors related to initiation in a sample of multiparous women with a history of a prior preterm birth.

SUBJECTS AND METHODS

Data for a subsample of women (n=130) were derived from a randomized clinical trial testing a home visit intervention to improve birth outcomes. The subsample included women who gave birth to an infant greater than 35 weeks of gestation. All participants received standard prenatal care. Intervention participants (n=73) also received home visits by certified nurse-midwives. Visits were guided by protocols to improve factors associated with poor birth outcomes and maternal and infant health. Descriptive and logistic regression analyses were used, controlling for factors previously associated with breastfeeding.

RESULTS

Although 85% of women reported an intention to breastfeed, only 65% reported initiating breastfeeding at 48 hours postpartum. After controlling for race, income, marital status, smoking, and age, higher maternal education and lower pregravid body mass index were associated with higher rates of initiation (odds ratio [OR]=1.30, p=0.010 and OR=0.94, p=0.007, respectively). Lower levels of depressive symptoms (OR=0.95, p=0.039) and higher levels of prenatal stress (OR=1.11, p=0.042) increased the likelihood of initiating breastfeeding. No difference between groups emerged, although women in the intervention group with more home visit time were more likely to report breastfeeding (p=0.007).

CONCLUSIONS

Modifiable risk factors were associated with rates of breastfeeding initiation. It may be possible to use protocols delivered via nurse-midwife home visits within a global intervention to increase breastfeeding initiation.

Metabolomics perspectives in pediatric research

Increasing evidence points toward the critical and long-term involvement of prenatal and early nutrition and lifestyle on later health and disease risk predisposition. Metabolomics is now a well-established top-down systems biology approach that explores the genetic-environment-health paradigm. The generalization of such approaches has opened new research areas to deepen our current understanding of many physiological processes, as well as foods and nutrient functionalities in target populations. It is envisioned that this will provide new avenues toward preventive medicine and prognostic strategies for tailored therapeutic and personalized nutrition management. The development of systems biology approaches and the new generation of biomarker patterns will provide the opportunity to associate complex metabolic regulations with the etiology of multifactorial pediatric diseases. This may subsequently lead to the development of system mechanistic hypotheses that could be targeted with new nutritional personalized concepts. Therefore, this review aims to describe recent applications of metabolomics in preclinical and clinical fields with insights into disease diagnostics/monitoring and improvement of homeostasis metabolic regulation that may be translatable to novel therapeutic and nutrition advances in pediatric research.

Pregravid body mass index is associated with early introduction of complementary foods

OBJECTIVE

To determine whether women who entered pregnancy overweight or obese were less likely to follow American Academy of Pediatrics guidelines for introducing complementary foods to infants after 4 months of age. In addition, we explored whether psychological factors accounted for any of the effect of pregravid body mass index on age of complementary food introduction.

DESIGN

A prospective cohort study from 2001 to 2005 that recruited pregnant women between 15 to 20 gestational weeks with follow-up through 12 months postpartum from University of North Carolina hospitals (n=550).

STATISTICAL ANALYSIS

Multinomial models were used to estimate relative risk ratios. The outcome was age of complementary food introduction, categorized as younger than 4 months of age, 4 to 6 months, and 6 months or later (referent). Maternal body mass index was categorized as underweight (<18.5), normal weight (18.5 to 24.9), and overweight/obese (≥25). A series of regression analyses tested mediation by psychological factors measured during pregnancy (depressive symptoms, stress, and anxiety).

RESULTS

More than a third of the study population (35.7% of 550) entered pregnancy overweight/obese. The majority of participants (75.3%) introduced foods to their infants between 4 and 6 months of age. Compared with normal-weight women, those who were overweight/obese before pregnancy were more likely (relative risk ratios=2.22 [95% CI 1.23 to 4.01]) to introduce complementary foods before the infant was 4 months old, adjusting for race, education, and poverty status. Depressive symptoms, stress, and anxiety did not account for any of the effect of pregravid overweight/obesity on early food introduction.

CONCLUSIONS

The results suggest that overweight and obese women are more likely to introduce complementary foods early and that psychological factors during pregnancy do not influence this relationship. Future studies need to explore why overweight/obese women are less likely to meet the American Academy of Pediatrics recommendations for the introduction of complementary food.

Maternal obesity, psychological factors, and breastfeeding initiation

OBJECTIVE

Maternal obesity has been associated with lower initiation of breastfeeding, but reasons for why this association exists have not been well studied. In this study, we examined associations among prepregnancy obesity, psychological factors during pregnancy, and breastfeeding initiation.

METHODS

Data came from the postpartum component of the Pregnancy, Infection, and Nutrition study, a prospective cohort study. Pregnant women were recruited from the University of North Carolina hospitals between January 2001 and June 2005. This analysis used data from 688 women followed from pregnancy to 3 months postpartum. Multivariable binomial regression was used to determine the association between having a body mass index (BMI) >26 kg/m(2) before pregnancy and breastfeeding initiation. We tested for mediation of the association between pregravid BMI and breastfeeding initiation by certain psychological factors during pregnancy (depressive symptoms, perceived stress, anxiety, and self-esteem).

RESULTS

Women who began pregnancy overweight or obese (BMI >26 kg/m(2)) had almost four times the risk of not initiating breastfeeding compared with underweight or normal weight women (BMI ≤26 kg/m(2)) (risk ratio = 3.94 [95% confidence interval 2.17, 7.18]) after adjusting for race, poverty level, education level, and marital status. Depressive symptoms, perceived stress, anxiety, and self-esteem levels during pregnancy were not found to mediate the association between pregravid BMI and breastfeeding initiation.

CONCLUSIONS

Women who started pregnancy either overweight or obese were more likely to not initiate breastfeeding. Contrary to expectations, pregnancy-related psychological factors did not influence this relationship.

Implementation of the new institute of medicine gestational weight gain guidelines

In May 2009, the Institute of Medicine (IOM) introduced revised gestational weight gain guidelines that were based on balancing the benefits and risks of weight gain for both the mother and child's health. This article provides an overview of these new recommendations, explaining the key changes made from the previous 1990 IOM recommendations. The important role of health care providers of pregnant women in the implementation of the new recommendations is detailed, and specific guidance for troubleshooting issues that may be encountered when helping women achieve appropriate gestational weight gains is provided.

Maternal Variables Influencing Duration of Breastfeeding Among Low-Income Mothers

This study used a retrospective comparison of 2 naturally occurring groups, first to examine how exclusive versus partial breastfeeding relates to duration of breastfeeding and, second, to determine if factors such as age and body mass index are associated with exclusive versus partial breastfeeding duration. These factors were hypothesized to influence the amount of breastfeeding in a sample of 42 low-income mothers enrolled in the Supplemental Nutrition Program for Women, Infants, and Children of a predominately rural, Midwestern county. This study examined de-identified data from a state database spanning a calendar year. Breastfeeding behavior, age, and body mass index measurements for mothers giving birth within the first 6 months of that year were analyzed. Exclusive breastfeeding mothers breastfed longer, were of older age, and had lower body mass indexes than partial breastfeeding mothers. These findings further describe characteristics of low-income breastfeeding women. Understanding how factors associated with exclusive versus partial breastfeeding affect breastfeeding duration may inform clinicians and researchers of areas for future interventions.

Dietary restraint and gestational weight gain

OBJECTIVE

To determine whether a history of preconceptional dieting and restrained eating was related to higher weight gains in pregnancy.

DESIGN

Dieting practices were assessed among a prospective cohort of pregnant women using the Revised Restraint Scale. Women were classified on three separate subscales as restrained eaters, dieters, and weight cyclers.

SUBJECTS

Participants included 1,223 women in the Pregnancy, Infection, and Nutrition Study.

MAIN OUTCOME MEASURES

Total gestational weight gain and adequacy of weight gain (ratio of observed/expected weight gain based on Institute of Medicine recommendations).

STATISTICAL ANALYSES PERFORMED

Multiple linear regression was used to model the two weight-gain outcomes, while controlling for potential confounders including physical activity and weight-gain attitudes.

RESULTS

There was a positive association between each subscale and total weight gain, as well as adequacy of weight gain. Women classified as cyclers gained an average of 2 kg more than noncyclers and showed higher observed/expected ratios by 0.2 units. Among restrained eaters and dieters, there was a differential effect by body mass index. With the exception of underweight women, all other weight status women with a history of dieting or restrained eating gained more weight during pregnancy and had higher adequacy of weight gain ratios. In contrast, underweight women with a history of restrained eating behaviors gained less weight compared to underweight women without those behaviors.

CONCLUSIONS

Restrained eating behaviors were associated with weight gains above the Institute of Medicine's recommendations for normal, overweight, and obese women, and weight gains below the recommendations for underweight women. Excessive gestational weight gain is of concern because of its association with postpartum weight retention. The dietary restraint tool is useful for identifying women who would benefit from nutritional counseling prior to or during pregnancy with regard to achieving targeted weight-gain recommendations.

A systematic review of maternal obesity and breastfeeding intention, initiation and duration

Background

Breastfeeding behaviour is multifactorial, and a wide range of socio-cultural and physiological variables impact on a woman's decision and ability to breastfeed successfully. An association has been reported between maternal obesity and low breastfeeding rates. This is of public health concern because obesity is rising in women of reproductive age and the apparent association with increased artificial feeding will lead to a greater risk of obesity in children. The aim of this paper is to examine the relationship between maternal overweight and obesity and breastfeeding intention and initiation and duration.

Methods

A systematic review was conducted in January and February 2007, using the following databases: Medline, CINAHL and the Australian Breastfeeding Association's Lactation Resource Centre. Studies which have examined maternal obesity and infant feeding intention, initiation, duration and delayed onset of lactation were tabulated and summarised.

Results

Studies have found that obese women plan to breastfeed for a shorter period than normal weight women and are less likely to initiate breastfeeding. Of the four studies that examined onset of lactation, three reported a significant relationship between obesity and delayed lactogenesis. Fifteen studies, conducted in the USA, Australia, Denmark, Kuwait and Russia, have examined maternal obesity and duration of breastfeeding. The majority of large studies found that obese women breastfed for a shorter duration than normal weight women, even after adjusting for possible confounding factors.

Conclusion

There is evidence from epidemiological studies that overweight and obese women are less likely to breastfeed than normal weight women. The reasons may be biological or they may be psychological, behavioral and/or cultural. We urgently need qualitative studies from women's perspective to help us understand women in this situation and their infant feeding decisions and behaviour.

The declining phase of lactation: peripheral or central, programmed or pathological?

In most species the functional activity of the mammary gland during lactation follows a biphasic developmental pattern. This pattern starts with a rapid increase in milk output that occurs with secretory activation and continues with a more gradual increase until the point of peak lactation is reached. Following this gain-of-function phase, the ability of the gland to produce milk decreases. This decrease occurs even if the lactation is prolonged by the presence of continued suckling stimulus and complete milk removal. This review describes the current state of our knowledge concerning the factors that regulate milk synthesis capacity by the mammary gland during the lactation cycle. The review describes four potential alternatives as mechanisms governing the process, which we refer to as secretory diminution. These alternatives are not presented as mutually exclusive of each other or other possible mechanisms, but are proposed as potential contributing mechanisms.

The association of maternal overweight and obesity with breastfeeding duration

OBJECTIVE

To determine whether maternal prepregnancy overweight or obesity has an independent effect on breastfeeding duration.

STUDY DESIGN

A prospective birth cohort study of 1803 live-born children and their mothers ascertained through antenatal clinics at the major tertiary obstetric hospital in Perth, Australia, were followed until 3 years of age. Unconditional logistic, Cox regression, and Kaplan Meier analyses were used to model the association between maternal prepregnancy overweight and obesity and the duration of predominant or any breastfeeding allowing for adjustment of confounders (infant factors: gender, birth weight, gestational age, age solids introduced, and older siblings; maternal factors: smoking, education, age, race, marital status, pregnancy and birth complications, cesarean section, and socioeconomic status).

RESULTS

Overweight and obese women were more likely to have discontinued breastfeeding at any time before 6 months than normal weight women (P < .0005) following adjustment for potential confounders.

CONCLUSION

We have shown that prepregnancy body mass index is associated with reduced breastfeeding duration, and that mothers who are overweight or obese before pregnancy tend to breastfeed their infants for a shorter duration than normal weight mothers independent of maternal socioeconomic and demographic characteristics.

The effect of overnourishing singleton-bearing adult ewes on nutrient partitioning to the gravid uterus

Overnourishing the singleton-bearing adolescent sheep throughout pregnancy promotes maternal tissue synthesis at the expense of the nutrient requirements of the gravid uterus. Consequently, the growth of the placenta is impaired and results in the premature delivery of low-birth-weight lambs relative to moderately fed adolescents of equivalent age. To establish if this phenomenon is unique to the growing animal, singleton pregnancies to a single sire were established by embryo transfer into primiparous adult ewes who had attained the normal mature body size for their genotype. Thereafter ewes were offered a maintenance or a high level of a complete diet throughout gestation. High maternal intakes resulted in elevated maternal insulin, no significant change in growth hormone or glucose, and attenuated progesterone and NEFA concentrations. Live weight gain during the first 93 d of gestation was 48 and 244 g/d, and adiposity score at term was 2.4 and 3.7 in the maintenance and high groups, respectively (P<0.001). In spite of achieving levels of adiposity similar to overnourished adolescents, placental (477 (sem 30) v. 518 (sem 41) g) and fetal (5190 (sem 320) v. 5420 (sem 250) g) weights were equivalent in maintenance and high groups. Gestation length was shorter (P<0.01) and colostrum yield at parturition lower (P<0.05) in high v. maintenance dams. Thus, adult sheep appear to be relatively insensitive to the oversupply of nutrients during pregnancy and have the ability to meet the nutrient requirements for normal conceptus growth in spite of their increased adiposity.

Maternal obesity and breast-feeding practices

BACKGROUND

Maternal obesity has been associated with poor lactation in animal models, but the results of related research in humans are inconclusive.

OBJECTIVE

We tested the hypothesis that women who are obese before pregnancy or who gain excessive weight during pregnancy are less likely to initiate and maintain breast-feeding than are their normal-weight counterparts.

DESIGN

We analyzed 124 151 mother-infant pairs from the Pediatric Nutrition Surveillance System and the Pregnancy Nutrition Surveillance System. Body mass index (BMI) before pregnancy and gestational weight gain were categorized according to guidelines from the Institute of Medicine. Multiple logistic regression was used to identify the association between maternal obesity and breast-feeding initiation (n = 51 329), and multiple linear regression was used to examine the effect of maternal obesity on breast-feeding duration among women who initiated breast-feeding (n = 13 234).

RESULTS

Regardless of gestational weight gain, obese women were less likely to initiate breast-feeding than were women with a normal BMI before pregnancy who also gained the recommended weight during pregnancy. Maternal BMI before pregnancy and gestational weight gain were each independently associated with duration of breast-feeding. Women who were obese before pregnancy breast-fed approximately 2 wk less than did their normal-weight counterparts, and women who either failed to reach or exceeded the recommended gestational weight gain breast-fed approximately 1 wk less than did those who gained the recommended gestational weight.

CONCLUSIONS

Both obesity before pregnancy and inadequate weight gain during pregnancy have a negative effect on breast-feeding practice. Women who are obese before pregnancy or who gain inadequate weight during pregnancy need extra support for breast-feeding.