Body Composition During Pregnancy: Longitudinal Changes and Method Comparisons.

The Pregnancy Obesity Nutrition and Child Health study is a longitudinal study of reproductive health. Here we analyzed body composition of normal-weight and obese Swedish women by three methods during each trimester of pregnancy. Cross-sectional and longitudinal fat mass estimates using quantitative magnetic resonance (QMR) and bioelectrical impedance analysis (BIA) (Tanita MC-180MA-III) were compared with fat mass determined by air displacement plethysmography (ADP) in pregnancy weeks 8-12, 24-26, and 35-37 in normal-weight women (n = 122, BMI = 22.1 ± 1.6 kg/m2) and obese women (n = 29, BMI = 34.6 ± 3.6 kg/m2). ADP results were calculated from pregnancy-adjusted fat-free mass densities. Mean fat mass by QMR and ADP were similar in obese women, although with wide limits of agreement. In normal-weight women, QMR overestimated mean fat mass in all trimesters, with systematic overestimation at low fat mass values in trimesters 1 and 3. In obese women, fat mass by BIA was grossly underestimated and imprecise in all trimesters, especially at higher values in trimester 2. In normal-weight women, fat mass by BIA was moderately lower than by ADP in trimester 1, similar in trimester 2, and moderately higher in trimester 3. QMR and ADP assessed fat mass changes similarly in obese women, whereas BIA overestimated fat mass changes in normal-weight women. Mean fat mass and fat mass changes by QMR and pregnancy-adjusted ADP were similar in pregnant obese women. Mean fat mass by QMR and fat mass changes by BIA were higher than corresponding values determined by pregnancy-adjusted ADP in normal-weight women.

Maternal obesity and gestational diabetes mellitus affect body composition through infancy: the PONCH study.

BACKGROUND: To determine how maternal obesity or gestational diabetes mellitus (GDM) affect infant body size and body composition during the first year of life. METHODS: Eighty three normal-weight (NW) women, 26 obese (OB) women, and 26 women with GDM were recruited during pregnancy. Infant body composition was determined by air-displacement plethysmography at 1 and 12 weeks, and anthropometric measurements made until 1 year of age. RESULTS: Girl infants born to OB women and women with GDM had a higher body-fat percentage (BF%) at 1 and 12 weeks of age than girls born to NW women. Girls had higher BF% than boys in OB and GDM groups only. Maternal HbA1c and fasting plasma glucose correlated with girl infant BF% at 1 week of age. Maternal weight at start of pregnancy correlated with birthweight in NW and OB groups, but not the GDM group. OB group infants showed greater BMI increases from 1 week to 1 year than both NW and GDM group infants. CONCLUSION: Results show that both maternal glycaemia and obesity are determinants of increased early life adiposity, especially in girls, with glycaemic levels being more influential than maternal weight for infants born to women with GDM.

A randomized longitudinal dietary intervention study during pregnancy: effects on fish intake, phospholipids, and body composition.

BACKGROUND: Fish and meat intake may affect gestational weight gain, body composition and serum fatty acids. We aimed to determine whether a longitudinal dietary intervention during pregnancy could increase fish intake, affect serum phospholipid fatty acids, gestational weight gain and body composition changes during pregnancy in women of normal weight participating in the Pregnancy Obesity Nutrition and Child Health study. A second aim was to study possible effects in early pregnancy of fish intake and meat intake, respectively, on serum phospholipid fatty acids, gestational weight gain, and body composition changes during pregnancy. METHODS: In this prospective, randomized controlled study, women were allocated to a control group or to a dietary counseling group that focused on increasing fish intake. Fat mass and fat-free mass were measured by air-displacement plethysmography. Reported intake of fish and meat was collected from a baseline population and from a subgroup of women who participated in each trimester of their pregnancies. Serum levels of phospholipid arachidonic acid (s-ARA), eicosapentaenoic acid (s-EPA), and docosahexaenoic acid (s-DHA) were measured during each trimester. RESULTS: Weekly fish intake increased only in the intervention group (n = 18) from the first to the second trimester (median difference 113 g, p = 0.03) and from the first to the third trimester (median difference 75 g, p = 0.01). In the first trimester, fish intake correlated with s-EPA (r = 0.36, p = 0.002, n = 69) and s-DHA (r = 0.34, p = 0.005, n = 69), and meat intake correlated with s-ARA (r = 0.28, p = 0.02, n = 69). Fat-free mass gain correlated with reported meat intake in the first trimester (r = 0.39, p = 0.01, n = 45). CONCLUSIONS: Dietary counseling throughout pregnancy could help women increase their fish intake. Intake of meat in early pregnancy may increase the gain in fat-free mass during pregnancy.

Lower vitamin D status in obese compared with normal-weight women despite higher vitamin D intake in early pregnancy.

BACKGROUND: Obesity is associated with lower vitamin D concentrations than normal-weight. Pregnancy may affect vitamin D status, especially in obese subjects. AIMS: The purpose of this study was to compare vitamin D status and intake between obese and normal-weight women during pregnancy. METHODS: Twenty-five obese and 80 normal-weight women were recruited in the Western Sweden region (latitude 57°N). Blood samples and information on diet and sun exposure were collected in each trimester during pregnancy. RESULTS: During summer months, 12% of normal-weight and 50% of obese women in the first trimester had serum 25(OH)D concentrations <50 nmol/L (P < 0.01). Supplement use, body fat mass, season of blood sampling, and travelling to southern latitudes were the most important determinants of vitamin D status. Obese women had higher reported dietary vitamin D intake in early pregnancy compared with normal-weight women. Usage of supplements containing vitamin D was 61% in early pregnancy and declined thereafter. Nine percent of normal-weight and 33% of obese women (P < 0.01) reported a dietary vitamin D intake according to national recommendations in the beginning of pregnancy. CONCLUSIONS: Half of the obese women had what could be considered as suboptimal vitamin D status in early pregnancy and lower vitamin D status compared with normal-weight women despite reporting a higher dietary vitamin D intake. A majority of the women did not reach intake of vitamin D according to dietary recommendations.

Accuracy of quantitative magnetic resonance and eight-electrode bioelectrical impedance analysis in normal weight and obese women.

BACKGROUND & AIMS: Quantitative magnetic resonance (QMR) has previously been shown to both overestimate and underestimate average fat mass (FM) in humans. Eight-electrode bioelectrical impedance analysis (BIA) has previously been found biased as well as successfully validated. We report cross-sectional accuracy of QMR and eight-electrode BIA evaluated with air displacement plethysmography (ADP) as reference method. METHODS: Fat mass and fat free mass (FFM) by QMR and eight-electrode BIA were evaluated against ADP as reference in 38 normal weight and 30 obese women. Total body water estimates by QMR and eight-electrode BIA were compared. RESULTS: Fat mass was overestimated by QMR (1 ± 2 kg, p < 0.001) and was underestimated by eight-electrode BIA (1 ± 3 kg, p = 0.03, Bonferroni adjusted p = 0.29) in normal weight women. Fat mass was underestimated by both QMR (2 ± 2 kg, p < 0.001) and eight-electrode BIA (9 ± 3 kg, p < 0.001) in obese women. Fat free mass biases were of similar magnitude but in opposite direction to FM biases. Total body water estimates were larger by eight-electrode BIA compared to QMR (1-10 kg). CONCLUSIONS: Fat mass and FFM by QMR were both biased but in opposite directions in both normal weight and obese women. Eight-electrode BIA FM and FFM estimates were imprecise and biased in obese women. Thus, QMR is more precise and more accurate than eight-electrode BIA for estimating body composition in women, but is not accurate enough to be used for individual single assessment of body composition.