Kendra E. Brett

Maternal–Fetal Nutrient Transport in Pregnancy Pathologies: The Role of the Placenta

Appropriate in utero growth is essential for offspring development and is a critical contributor to long-term health. Fetal growth is largely dictated by the availability of nutrients in maternal circulation and the ability of these nutrients to be transported into fetal circulation via the placenta. Substrate flux across placental gradients is dependent on the accessibility and activity of nutrient-specific transporters. Changes in the expression and activity of these transporters is implicated in cases of restricted and excessive fetal growth, and may represent a control mechanism by which fetal growth rate attempts to match availability of nutrients in maternal circulation. This review provides an overview of placenta nutrient transport with an emphasis on macro-nutrient transporters. It highlights the changes in expression and activity of these transporters associated with common pregnancy pathologies, including intrauterine growth restriction, macrosomia, diabetes and obesity, as well as the potential impact of maternal diet. Molecular signaling pathways linking maternal nutrient availability and placenta nutrient transport are discussed. How sexual dimorphism affects fetal growth strategies and the placenta’s response to an altered intrauterine environment is considered. Further knowledge in this area may be the first step in the development of targeted interventions to help optimize fetal growth.

Can we modify the intrauterine environment to halt the intergenerational cycle of obesity

Child obesity is a global epidemic whose development is rooted in complex and multi-factorial interactions. Once established, obesity is difficult to reverse and epidemiological, animal model, and experimental studies have provided strong evidence implicating the intrauterine environment in downstream obesity. This review focuses on the interplay between maternal obesity, gestational weight gain and lifestyle behaviours, which may act independently or in combination, to perpetuate the intergenerational cycle of obesity. The gestational period, is a crucial time of growth, development and physiological change in mother and child. This provides a window of opportunity for intervention via maternal nutrition and/or physical activity that may induce beneficial physiological alternations in the fetus that are mediated through favourable adaptations to in utero environmental stimuli. Evidence in the emerging field of epigenetics suggests that chronic, sub-clinical perturbations during pregnancy may affect fetal phenotype and long-term human data from ongoing randomized controlled trials will further aid in establishing the science behind ones predisposition to positive energy balance.

Young Children and Parental Physical Activity Levels Findings from the Canadian Health Measures Survey

BACKGROUND Physical inactivity is a global public health concern. The relationship between dependent children in the home and parental physical activity has not been quantified using objective measures, nor has the relative association of the physical activity levels of mothers and fathers been examined. PURPOSE To investigate the association of children of different ages in the home on two measures of parental physical activity: daily moderate-to-vigorous physical activity (MVPA) and likelihood of meeting the guideline of 150 minutes of MVPA per week accumulated in 10-minute bouts. METHODS Data were from the 2007-2009 Canadian Health Measures Survey (n=2315), and analyses were conducted between February and December 2011. MVPA was measured directly using accelerometry. Linear (minutes of MVPA) and logistic (meeting physical activity guidelines) regression models were performed to determine if the presence, number of children, or the age of the youngest child at home was associated with parental physical activity. All models were adjusted for parental age, marital status, household income, employment, and BMI. RESULTS Mothers whose youngest child was aged <6 years and fathers whose youngest was aged 6-11 years engaged in fewer minutes of daily MVPA than those without dependent children. Linear regression results identified that in comparison to those without children, women whose youngest child in the home was aged <6 years participated in 7.7 minutes less activity per day (p=0.007) whereas men engaged in 5.7 fewer minutes per day, or 54 and 40 minutes per week less, respectively. Similarly, logistic regression analyses indicated that both women and men were less likely to meet guidelines if their youngest child in the home was aged <6 years (OR=0.31, 95% CI=0.11, 0.87; OR=0.34, 95% CI=0.13, 0.93). CONCLUSIONS The physical activity level of parents with young children present in the home was lower than that of those without children. Given the many physiologic, psychological, and social benefits of healthy active living, research efforts should continue to focus on strategies to encourage parents with young children to establish or re-engage in a physically active lifestyle, not only for their own health but to model healthy behavior for the next generation.

Canadian Consensus on Female Nutrition: Adolescence, Reproduction, Menopause, and Beyond

OBJECTIVES To provide health care professionals in Canada with the basic knowledge and tools to provide nutrition guidance to women through their lifecycle. OUTCOMES Optimal nutrition through the female lifecycle was evaluated, with specific focus on adolescence, pre-conception, pregnancy, postpartum, menopause, and beyond. The guideline begins with an overview of guidance for all women, followed by chapters that examine the evidence and provide recommendations for the promotion of healthy nutrition and body weight at each life stage. Nutrients of special concern and other considerations unique to each life stage are discussed in each chapter. EVIDENCE Published literature, governmental and health agency reports, clinical practice guidelines, grey literature, and textbook sources were used in supporting the recommendations made in this document. VALUES The quality of evidence was rated using the criteria described in the report of the Canadian Task Force on Preventive Health Care. CHAPTER 2: GENERAL FEMALE NUTRITION: Summary Statements Recommendations CHAPTER 3: ADOLESCENCE NUTRITION: Summary Statements Recommendations CHAPTER 4: PRE-CONCEPTUAL NUTRITION: Summary Statement Recommendations CHAPTER 5: NUTRITION IN PREGNANCY: Summary Statements Recommendations CHAPTER 6: POSTPARTUM NUTRITION AND LACTATION: Summary Statements Recommendations CHAPTER 7: NUTRITION DURING MENOPAUSE AND BEYOND: Summary Statement Recommendations.

Placenta nutrient transport-related gene expression: the impact of maternal obesity and excessive gestational weight gain

Abstract Objective: Maternal obesity and excess gestational weight gain (GWG) increase the risk of delivering large infants. This study examined the associations between maternal obesity and GWG on the expression of genes involved in fatty acid, amino acid and glucose transport, and the mechanistic target of rapamycin (mTOR) and insulin signaling axes in the placenta. Methods: Placenta samples were obtained from lean (n = 11) and obese (n = 10) women. Gene expression in the placenta was measured using polymerase chain reaction. Results: There were no differences in placenta gene expression between the lean and obese women, with the exception of lower expression of mTOR in the women with obesity who delivered male offspring (obese n = 6; lean n = 7). GWG in excess of the upper limit of the body mass index (BMI) specific guidelines was correlated with increased expression of SNAT1 and decreased expression of FABP3, mTOR, IRS1 and IGF1R. Conclusions: Variations in GWG may alter the expression of genes involved in regulating placental nutrient transport. Future research on placental nutrient transport should account for the sex of the offspring and the percentage of GWG that is gained above the upper limit for the pre-pregnancy BMI.

Prenatal physical activity and diet composition affect the expression of nutrient transporters and mTOR signaling molecules in the human placenta.

INTRODUCTION Adequate nutrient delivery to the fetus is essential for optimal growth. Differences in prenatal physical activity level and diet quality influence maternal energy balance and these factors may alter placental nutrient transport. We investigated the associations between meeting physical activity guidelines and the quality of maternal diet on the expression of genes involved in fatty acid, amino acid and glucose transport, and mammalian target of rapamycin (mTOR) and insulin signaling in the placenta from 16 term pregnancies. METHODS Physical activity was directly measured with accelerometry, diet composition was assessed with 24 h dietary recalls, and gene expression was measured with custom polymerase chain reaction (PCR) arrays. RESULTS Women who met physical activity guidelines had lower gene expression of fatty acid transport protein 4 (FATP4), insulin-like growth factor 1 (IGF1), and the beta non-catalytic subunit of AMP-activated protein kinase (AMPK), and a higher expression of SNAT2. There was a strong positive correlation observed between total sugar intake and glucose transporter 1 (GLUT1) (r = 0.897, p = 0.000, n = 12), and inverse correlations between total sugar and mTOR and IGF1 expression. Percentage of total calories from protein was inversely related to insulin-like growth factor 1 receptor (IGF1R) (r = -0.605, p = 0.028, n = 13). DISCUSSION Variations in maternal physical activity and diet composition altered the expression of genes involved in fatty acid, amino acid and glucose transport and mTOR signaling. Future research on placental nutrient transport should include direct measures of maternal PA and dietary habits to help eliminate confounding factors.

Self-report Pregnancy Physical Activity Questionnaire overestimates physical activity.

ObjectivesPhysical activity (PA) research during pregnancy relies heavily on indirect/subjective measures of PA, which may be less accurate than directly measured PA. We tested whether the Pregnancy Physical Activity Questionnaire (PPAQ) could accurately estimate PA by comparing PPAQ results to directly measured PA.MethodsIn a sample of 29 women who completed the PPAQ, PA was directly measured in the second trimester of pregnancy using Actical® accelerometers (valid day = 10+ hours; 4–7 valid days). Activity variables from the PPAQ were calculated using all questions, and also by only considering the leisure time section. Women were classified as ‘active’ or ‘non-active’ using Canadian PA guidelines for adults (150 minutes moderate to vigorous PA (MVPA)/ week, bouts of 10+ minutes). Bonferroni corrections were used to adjust for multiple comparisons. Data presented as mean ± standard deviation or median (interquartile range).ResultsThe PPAQ overestimated MVPA by 12.12 (14.34) hours/week in the combined sample, and the difference remained substantial when investigating the non-active [overestimate = 11.54 (10.10) hrs/wk] and the active women [overestimate = 16 ± 11 hrs/wk] separately. PPAQ-measured PA variables did not correlate with any of their respective Actical®-measured variables (p > 0.008). The leisure time PPAQ questions overestimated MVPA by 1 ± 3 hrs/wk, with a positive correlation between PPAQ-leisure time MVPA and Actical®-measured MVPA (r= 0.565, p = 0.001).ConclusionThe PPAQ significantly overestimates MVPA and does not provide an accurate estimate of PA in pregnancy. While PPAQ leisure time questions may help distinguish trends in PA, data from subjective questionnaires may result in misinterpretation of relationships between prenatal PA and health outcomes.RésuméObjectifsLa recherche sur l’activité physique (AP) durant la grossesse recourt largement aux indicateurs indirects/subjectifs de l’AP, lesquels peuvent être moins exacts que l’AP directement mesurée. Nous avons testé l’outil Pregnancy Physical Activity Questionnaire (PPAQ) pour voir s’il estime l’AP de façon exacte, en comparant les résultats du PPAQ aux résultats obtenus à partir de mesures directes de l’AP.MéthodeDans un échantillon de 29 femmes ayant rempli le PPAQ, nous avons directement mesuré l’AP au deuxième trimestre de la grossesse à l’aide d’accéléromètres Actical® (jour admissible = 10+ heures; 4–7 jours admissibles). Les variables d’activité du PPAQ ont été calculées en utilisant toutes les questions, et aussi en ne tenant compte que de la section sur le temps libre. Les femmes ont été classées comme étant «actives» ou «non actives» selon les Directives canadiennes en matière d’AP à l’intention des adultes (150 minutes d’activité physique d’intensité modérée à élevée (APIME)/semaine, en épisodes de 10+ minutes). Nous avons appliqué la correction de Bonferroni pour permettre les comparaisons multiples. Les données ont été présentées sous forme de moyenne ± écart type ou de médiane (écart interquartile).RésultatsLe PPAQ a surestimé l’APIME par 12,12 (14,34) heures/semaine dans l’échantillon combiné, et la différence est demeurée importante lorsque nous avons étudié séparément les femmes non actives [surestimation = 11,54 (10,10) h/sem] et les femmes actives [surestimation = 16 ± 11 h/sem]. Les variables d’AP mesurées selon le PPAQ n’étaient en corrélation avec aucune des variables correspondantes mesurées par Actical® (p > 0,008). Les questions du PPAQ (temps libre) surestimaient l’APIME de 1 ± 3 h/sem, avec une corrélation positive entre l’APIME mesurée selon les questions du PPAQ (temps libre) et l’APIME mesurée par Actical® (r = 0,565, p = 0,001).ConclusionLe PPAQ surestime l’APIME de façon significative et n’offre pas une estimation exacte de l’AP durant la grossesse. Les questions du PPAQ portant sur le temps libre peuvent aider à dégager des tendances dans l’AP, mais les données de questionnaires subjectifs peuvent entraîner une fausse interprétation des relations entre l’AP prénatale et les résultats de santé.

Parental Perceptions and Childhood Dietary Quality: Who Holds the Reins?

This chapter will focus on diet quality in children and specifically the parental perception of diet quality and how this might impact eating behaviours.