MUAC could help screen for Low Birth Weight and More in Pregnant Women

Simple color coded devices for triage always come first on our list at Maternova. In humanitarian settings a quick, lightweight band to wrap around an upper arm and make a referral decision is a lifesaver.  MUAC tapes are well-known for their role in child health, but were you aware of the use case for adults?

MUAC tapes used to screen pregnant women

MUAC tapes are used to assess the malnutrition status of pregnant women. The mid upper arm circumference has been shown to correlate well with Body Mass Index (BMI) and the Mid Upper Arm Circumference (MUAC) does not change much over the course of a pregnancy. Overall the MUAC measurement indicates protein reserves. Though there is not a firm consensus on the cutoff value, studies have used a range from 21 cm to 23.5 cm for pregnant women in a humanitarian setting. A 2021 study in Brazil supported earlier findings that suggest that MUAC tapes can be used as a 'shortcut' or surrogate approximating BMI.  India studies also report MUAC tapes being used to assess malnutrition in pregnant women.  Note that a different tape with a different length and color blocks is used for adults as opposed to adolescents or children.  

MUAC tapes can possibly predict low birth weight babies
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Beyond their role in assessing the nutrition status of pregnant mothers, the MUAC tape can also be used to assess women at risk of low birth weight babies. 

A study from several years ago indicates that there is no consensus on a cutoff but that a cutoff of 23 cm would be a way to identify more women at risk of delivering low birth weight babies.

Some sources note that the Mid Upper Arm Circumference tape can be used to assess intrauterine growth retardation (IUGR). The Sphere Project has used "MUAC <20.7cm as a cutoff for severe risk and <23cm as a cutoff for moderate risk. Suggested cut-off points for risk vary by country and range from 21cm to 23cm.

Of further note, the MUAC has been used in some studies to track women for obesity in pregnancy. Obesity puts a woman at risk of many health complications with moderate to severe impact on both mother and fetus. One study found that the MUAC had a sensitivity and specificity of 76% and 91% respectively. This study suggests 33 cm as a cutoff point-- above which women are identified as obese.  In South Africa, the cutoff point is 30 cm.The variability of cutoffs for both high and low BMI approximation using MUAC tapes speaks to the importance of adapting cutoffs to local populations.  

Note:  Nothing in this blog post should be taken as medical advice.  The post is meant to draw attention the use of the MUAC tape as a surrogate method for assessing BMI, but use of such methods should be overseen by appropriate health authorities.