Utility of published skinfold thickness equations for prediction of body composition in very young New Zealand children.

Measurement of body composition is increasingly important in research and clinical settings but is difficult in very young children. Bioelectrical impedance analysis (BIA) and air displacement plethysmography (ADP) are well-established but require specialist equipment so are not always feasible. Our aim was to determine if anthropometry and skinfold thickness measurements can be used as a substitute for BIA or ADP for assessing body composition in very young New Zealand children. We used three multi-ethnic cohorts: 217 children at a mean age of 24·2 months with skinfold and BIA measurements; seventy-nine infants at a mean age of 20·9 weeks and seventy-three infants at a mean age of 16·2 weeks, both with skinfold and ADP measurements. We used Bland-Altman plots to compare fat and fat-free mass calculated using all potentially relevant equations with measurements using BIA or ADP. We also calculated the proportion of children in the same tertile for measured fat or fat-free mass and tertiles (i) calculated using each equation, (ii) each absolute skinfold, and (iii) sum of skinfold thicknesses. We found that even for the best equation for each cohort, the 95 % limits of agreement with standard measures were wide (25-200 % of the mean) and the proportion of children whose standard measures fell in the same tertile as the skinfold estimates was ≤69 %. We conclude that none of the available published skinfold thickness equations provides good prediction of body composition in multi-ethnic cohorts of very young New Zealand children with different birth history and growth patterns.

Relationship between BMI and adiposity among different ethnic groups in 2-year-old New Zealand children.

Age- and sex-based BMI cut-offs are used to define overweight and obesity, but the relationship between BMI and body composition has not been very well studied in children or compared between children of different ethnic groups. Body size and composition in childhood are also influenced by size at birth. Our aim was to compare body size and composition at 2 years in children with different ethnicity and size at birth. We prospectively followed a multi-ethnic cohort of 300 children born with risk factors for neonatal hypoglycaemia (infants of diabetics, large or small at birth or late preterm) to 2 years corrected age. Complete data on weight, height and head circumference and body composition using bioelectrical impedance 24±1 months corrected age were available in 209 children. At birth, compared with European children, Chinese, Indian and other ethnicity children were lighter, and Indian children had smaller head circumferences, but birth lengths were similar in all ethnic groups. At 2 years, Pacific children were heavier and had higher BMI z scores, and Indian children had smaller head circumferences and lower BMI z scores than those from other ethnic groups. However, fat mass and fat-free mass indices were similar in all groups. At median BMI, fat mass:fat-free mass ratio was 23 % lower in Pacific than in Indian children (0·22 v. 0·27, P=0·03). BMI is not a good indicator of adiposity in this multi-ethnic cohort of 2-year-old New Zealand children.

Understanding the associations and significance of fetal movements in overweight or obese pregnant women: a systematic review.

INTRODUCTION: Presentation with decreased fetal movement (DFM) is associated with fetal growth restriction and stillbirth. Some studies report that DFM is frequent among overweight or obese mothers. We aimed to determine the significance and associations of fetal movements in women of increased body size. MATERIAL AND METHODS: This systematic review was conducted in accordance with the PRISMA statement and the protocol was registered with PROSPERO (CRD42016046352). Major databases were explored from inception to September 2017, using a predefined search strategy. We restricted inclusion to studies published in English and considered studies of any design that compared fetal movements in women of increased and normal body size. Two authors independently extracted data and assessed quality. RESULTS: We included 23 publications from 19 observational studies; data were extracted from 10 studies. Increased maternal body size was not associated with altered perception of fetal movement (four studies, 95 women, very low-quality evidence), but was associated with increased presentation for DFM (two cohort studies, 20 588 women, OR 1.56, 95% CI 1.27-1.92: three case-control studies, 3445 women, OR 1.32, 95% CI 1.12-1.54; low-quality evidence). Among women with DFM, increased maternal body size was associated with increased risk of stillbirth and fetal growth restriction (one study, 2168 women, very low-quality evidence). CONCLUSIONS: This systematic review identified limited evidence that women with increased body size are more likely to present with DFM but do not have impaired perception of fetal movements. In women with DFM, increased body size is associated with worse pregnancy outcome, including stillbirth.