The performance of various anthropometric assessment methods for predicting low birth weight in adolescent pregnant women

How to classify BMI among pregnant adolescents? A prospective cohort

OBJECTIVE

Pregnancy in adolescence is a global health issue, especially in developing countries. Additionally, the recommended gestational weight gain (GWG) is usually based on pre-pregnancy BMI and that might be complex for pregnant teens. The study objective was to compare three different methods of BMI classification and suggest the best way of determining pre-pregnancy BMI and monitoring GWG among pregnant adolescents.

DESIGN

Pre-pregnancy weight, weight at first prenatal visit, height, sociodemographic, reproductive and perinatal data were collected. Weighted kappa and McNemar statistics were used to assess agreement between the classification methods.

SETTING

Prof. Dr Jose Aristodemo Pinotti Women's Hospital, University of Campinas, Brazil.ParticipantsPrimiparas younger than 19 years of age and with less than 20 weeks of gestational age (n 150).

RESULTS

BMI of the primiparas was determined according to the WHO recommendation for adult women, the Child Growth Standards (CGS) and their gynaecological age (GA). The WHO and GA measurements presented a strong agreement with each other (κ w=0·99; 95 % CI 0·97, 1·00), but did not agree with the CGS classification (κ w=0·62; 95 % CI 0·50, 0·74 by WHO; κ w=0·62; 95 % CI 0·51, 0·74 by GA). Also, inadequate GWG was observed in 72·2 % of cases and was correlated with a higher rate of caesarean birth.

CONCLUSIONS

BMI classification according to the CGS differed from WHO and GA. However, CGS and WHO agreed on perinatal outcomes. We recommend using BMI classification by WHO to assess pregnant adolescents, since it is easily applied and better known among health professionals.

Pre-pregnancy body mass index classification and gestational weight gain on neonatal outcomes in adolescent mothers: A follow-up study

Introduction: Institute of Medicine gestational weight gain recommendations are based on body mass index (BMI) status using adult cut-off points for women of all ages, even though adolescents have specific criteria, like WHO and CDC, so adolescents can receive inadequate weight gain recommendations. Objectives: To estimate the proportion of classification disparity between the three criteria (WHO, CDC and IOM) of pre-pregnancy BMI status; and to analyze neonatal outcomes according to weight gain recommendation based on pre-pregnancy BMI using the three criteria. Methods: Follow-up study in pregnant adolescents 12–19 years. Sociodemographic, anthropometric and pregnancy data were obtained. Percentage of pre-pregnancy BMI classification disparity was calculated between three criteria. Gestational weight gain was categorized in adequate, low and high according to IOM. Regression models were used to analyze negative neonatal outcomes. Results: 601 pregnant adolescents were included, mean age was 16±1.4 years. For pre-pregnancy BMI classification, 28.5% had classification disparity using IOM vs WHO, and 14% when comparing IOM vs CDC. Greater classification disparity was observed as BMI increased. When using WHO categories, a high weight gain was associated with increased risk of having a low birth weight baby (OR: 1.91, CI95%: 1.03–3.53). For CDC criteria, a low weight gain was associated with increased risk of having a preterm baby (OR: 2.65; CI95%: 1.16–6.08) and a high weight gain was associated with low birth weight (OR: 2.10; CI95%: 1.10–4.01). For IOM criteria, a weight gain either low or high were associated with increased risk of low birth weight and preterm birth. Conclusion: There is pre-pregnancy BMI classification disparity using criteria for adolescents compared to adult criteria. Nevertheless, with WHO and CDC only a high gestational weight gain was a risk for negative neonatal outcome. It is important to have a BMI classification system for adolescents that better predicts neonatal outcomes.

Classificação antropométrica de gestantes: comparação entre cinco métodos diagnósticos utilizados na América Latina

Objetivo.

Verificar a concordância entre cinco métodos antropométricos na classificação nutricional de gestantes e comparar as classificações obtidas com a classificação nutricional da população brasileira de mulheres jovens não gestantes.

Método.

Estudo transversal com dados de 1 108 gestantes com idade de 19 a 35 anos atendidas de setembro de 2011 a abril de 2012 em serviços de pré-natal no estado de Pernambuco, Brasil. A classificação nutricional (baixo peso, peso adequado e sobrepeso/obesidade) foi realizada conforme os critérios de Mardones e Rosso, de Mardones et al., de Atalah et al., do Centro Latino Americano de Perinatologia (CLAP) e do Institute of Medicine de 2009 (IOM-2009). Estimaram-se os coeficientes kappa de concordância para os pares de métodos. O teste do qui-quadrado de bondade de ajuste foi utilizado para comparar a distribuição de frequências de cada categoria nutricional em cada método com a distribuição em não gestantes classificadas de acordo com índice de massa corporal (IMC, pontos de corte da OMS).

Resultados.

Os métodos concordaram entre si para o diagnóstico de sobrepeso/obesidade (kappa > 0,60) e discordaram em relação ao baixo peso (kappa ≤ 0,60), particularmente nas comparações do IOM-2009 (que utiliza o IMC pré-gestacional) com os demais. As distribuições de frequências amostrais obtidas com os cinco métodos diferiram da população de referência de não gestantes (P < 0,001), observando-se percentuais de sobrepeso/obesidade inferiores à prevalência nacional e percentuais de baixo peso superiores à prevalência nacional.

Conclusão.

As disparidades observadas podem ser atribuídas à heterogeneidade entre os métodos, justificando a realização de inquéritos para definir padrões antropométricos específicos para determinadas populações.