Newborn Body Fat: Associations with Maternal Metabolic State and Placental Size

et al. (2013) Newborn Body Fat: Associations with Maternal Metabolic State and Placental Size. PLoS ONE 8(2): e57467. doi:10.1371/journal.pone.0057467 Newborn Body Fat: Associations with Maternal Metabolic State and Placental Size Camilla M. Friis 0 Elisabeth Qvigstad 0 Marie Cecilie Paasche Roland 0 Kristin Godang 0 Nanna Voldner 0 Jens Bollerslev 0 Tore Henriksen 0 Cornelis B. Lambalk, VU University Medical Center, The Netherlands 0 1 Section for Obstetrics, Women and Children's Division, Rikshospitalet, Oslo University Hospital , Oslo , Norway , 2 Outpatient Clinic for Specialized Endocrinology, Division of Medicine, Rikshospitalet, Oslo University Hospital , Oslo , Norway , 3 Faculty of Medicine, University of Oslo , Oslo , Norway Background: Neonatal body composition has implications for the health of the newborn both in short and long term perspective. The objective of the current study was first to explore the association between maternal BMI and metabolic parameters associated with BMI and neonatal percentage body fat and to determine to which extent any associations were modified if adjusting for placental weight. Secondly, we examined the relations between maternal metabolic parameters associated with BMI and placental weight. Methods: The present work was performed in a subcohort (n = 207) of the STORK study, an observational, prospective study on the determinants of fetal growth and birthweight in healthy pregnancies at Oslo University Hospital, Norway. Fasting glucose, insulin, triglycerides, free fatty acids, HDL- and total cholesterol were measured at week 30-32. Newborn body composition was determined by Dual-Energy X-Ray Absorptiometry (DXA). Placenta was weighed at birth. Linear regression models were used with newborn fat percentage and placental weight as main outcomes. Results: Maternal BMI, fasting glucose and gestational age were independently associated with neonatal fat percentage. However, if placental weight was introduced as a covariate, only placental weight and gestational age remained significant. In the univariate model, the determinants of placenta weight included BMI, insulin, triglycerides, total- and HDL-cholesterol (negatively), gestational weight gain and parity. In the multivariable model, BMI, total cholesterol HDL-cholesterol, gestational weight gain and parity remained independent covariates. Conclusion: Maternal BMI and fasting glucose were independently associated with newborn percentage fat. This effect disappeared by introducing placental weight as a covariate. Several metabolic factors associated with maternal BMI were associated with placental weight, but not with neonatal body fat. Our findings are consistent with a concept that the effects of maternal BMI and a number of BMI-related metabolic factors on fetal fat accretion to a significant extent act by modifying placental weight. - Funding: The project has been financially supported by South-Eastern Norway Regional Health Authority, The National Resource Centre for Womens Health, Division of Obstetrics and Gynaecology, Oslo University Hospital, Rikshospitalet; The Department of Obstetrics, Women and Childrens Division, Oslo University Hospital, Rikshospitalet, Oslo, Norway; The Faculty of Medicine, Thematic Research Area, University of Oslo. The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript. Competing Interests: The authors have declared that no competing interests exist. Determinants of birthweight and neonatal body composition have gained increasing attention over the recent years. This interest has largely been driven by the well documented relation between anthropometric characteristics at birth and future health of the newborn [1]. In addition fetuses of small or large size are at increased risk of perinatal complications [2]. However, birthweight is only a crude measure of intrauterine growth and especially of neonatal body composition. Growth of the human fetus involves a characteristic accretion of adipose tissue in the last trimester. Neonatal body fat is therefore an important indicator of fetal energy supply and growth conditions [3,4]. Maternal body mass index (BMI) is one of the most consistent determinants of fetal weight, growth and body composition [4,5]. However, BMI is not a biological effector, and the mechanisms by which BMI exerts its effects on fetal growth and body composition remain largely unknown [6]. In general, besides placental endocrine functions, the factors governing the growth of a healthy fetus may be divided into three groups; the genetic potential of growth, maternal supply of nutrients and the capacity of the placenta to transfer nutrients from the maternal circulation to the fetus. In particular, maternal BMI may affect fetal growth and fat mass accretion both by modifying the supply of nutrients and by affecting placental nutrient transport capacity. Maternal BMI is positively associated with circulating glucose. Furthermore, maternal BMI and glucose are established as independent determinants of large for gestational age newborns and excessive body fat at birth [7,8]. Consequently, other factors than glucose is likely to play a role in the association between BMI and fetal fat mass accretion [7,9,10]. Studies of the effects of other metabolic factors linked to increasing BMI, like lipids (cholesterol, triglycerides and free fatty acids) and insulin on fetal growth are inconsistent [11,12]. While numerous studies have identified maternal nutritional and metabolic measures as determinants of fetal growth, fewer have evaluated the role of placental transport capacity in this relation [13,14]. Placenta has however, a pivotal role in fetal growth as all nutrients need to pass the syncytio-vascular layer of placenta in order to enter fetal circulation. Maternal BMI has been shown to affect both placental properties and weight, and placental weight is closely associated with fetal growth [15,16]. Placenta is furthermore believed to act as a nutrient sensor, up- or down regulating transport proteins according to the maternal environment [13]. Thus it is conceivable that some of the metabolic derangements associated with increasing BMI play a role in regulating placental function. There is no single parameter reflecting placental function, but placental transport capacity is dependent on exchange area as well as density of transport proteins. Under physiological conditions, it is reasonable to assume that placental weight is correlated to exchange area and therefore with total transport capacity [17,18]. The objective of the current study was first to explore the relationships between maternal nutritional and metabolic status (as reflected in maternal BMI, plasma levels of glucose, insulin, triglycerides, free fatty acids and cholesterol) on neonatal percentage body fat. Then we wanted to determine to which extent any associations were modified when (...truncated)