Technical briefing note

MUAC cut-off to define acute malnutrition among pregnant and nursing women

What is the current state of knowledge, what evidence exist and what is the current practice in the field?

There is no internationally agreed / recommended or accepted MUAC cut-off and thresholds to estimate or classify the nutritional status of children above 5 years of age, adolescents and adults.

In 2000, the UN SCN commissioned experts to review and produce recommendations on how to assess the nutritional status of adults in emergency-affected populations[1]. This paper describes notably how BMI and MUAC meet the criteria of an ideal index of nutritional status among adults. Authors clearly stated that their review didn’t include pregnant women and that research was needed to define specific cut-off points for BMI and MUAC that correlates to poor pregnancy outcomes.

In 2013, FHI 360 published a systematic review of the use cut-offs for MUAC in adolescents and adults[2]. The review included 11 cross-sectional and 12 longitudinal studies involving pregnant women and looked mainly at association between low MUAC and birth outcomes (only a few of these studies looked at associations with maternal health and the review doesn’t seem to refer to lactating women). Most of the studies show that low MUAC correlates with low birth weight mainly (and other negative outcomes). The choice of the cut-off defining MUAC as low ranged from 215 mm to 270 mm. Some countries used the median MUAC in their population as the cut-off. Here again, authors suggested that more research is needed to establish MUAC cut-off for pregnant women.

However, despite the lack of evidence in practice MUAC cut-off for moderate and severe acute malnutrition (or for being suspected nutritionally at risk) are used in cross-sectional surveys and as admission criteria to nutritional support programs for pregnant and lactating women, people living with HIV/AIDS and in case of chronical diseases.  

UNICEF has recommendations on criteria to diagnose SAM (not MAM) that is for adults over 18 years (BMI < 16 kg/m² and / or MUAC < 185 mm and / or bilateral pitting oedema)[3].

The HTP module 6 (measuring malnutrition – individual assessments[4]) explains that the most useful measure of undernutrition in adults is BMI, an indicator of weight deficit in relation to height. However, BMI cannot be used for pregnant women and nursing mothers notably because a pregnant woman’s weight will be related to the growth of the baby and because of changes in the body related to pregnancy and nursing and hence, MUAC is a the preferred nutritional index for this population.

The HTP module 6 refers to the Sphere standards that recommend 210 mm as an appropriate cut-off for selection of women nutritionally at risk during emergencies.

UNHCR and WFP recommend:

MUAC < 210 mm or < 230 mm[5] and second or third trimester for pregnant women

MUAC < 210 mm or < 230 mm⁵ and/or if breastfeeding problems or if the infant is not gaining weight adequately for nursing mothers with infant < 6 months.

Different MSF sections uses different MUAC < 185 mm or < 210 mm or < 230 mm to include pregnant women in SFPs. MSF published a literature review in 2013[6] and concluded that a conservative cut-off of < 230 mm is recommended to include most pregnant women at risk of LBW for their infants in the African and Asian contexts.

Practically, what shall we do?

Recommendations for definition of admission criteria in TSFP:

è  If resources are limited and/or the expected caseload high, it is recommended to continue using MUAC < 210 mm as admission criteria for pregnant women and for nursing mothers with infant < 6 months.

è  If resources and capacity allow, it is recommended to consider the more conservative cut-off of MUAC < 230 mm as admission criteria for pregnant women and for nursing mothers with infant < 6 months.

Recommendations for definition of index to use during mass screening exercise or cross-sectional surveys:

è  It is recommended to use the same MUAC cut-off across.