Mid-upper arm circumference: A surrogate for body mass index in pregnant women

Nutrition in pregnancy has implications for both mother and fetus, hence the importance of an accurate assessment at the booking visit during antenatal care. The body mass index (BMI, kg/m2) is currently the gold standard for measuring body fatness. However, pregnancy-associated weight gain and oedema, as well as late booking in our population setting, cause concern about the reliability of using the BMI to assess body fat or nutritional status in pregnancy. The mid-upper arm circumference (MUAC) has been used for many decades to assess malnutrition in children aged <5 years. Several studies have also shown a strong correlation between MUAC and BMI in both pregnant and non-pregnant adult populations.

To assess the correlation between the MUAC and BMI in pregnant women booking for antenatal care in the Metro West area of Cape Town, South Africa.

We conducted a cross-sectional study of women booking at four midwife obstetric units. Anthropometric measurements (height, weight and MUAC) were carried out on pregnant women at their first antenatal booking visit.

The results showed a strong correlation between MUAC and BMI in pregnant women up to 30 weeks' gestation. The correlation was calculated at 0.92 for the entire group. The MUAC cut-offs for obesity (BMI >30) and malnutrition (BMI <18.5) were calculated as 30.57 cm and 22.8 cm, respectively.

MUAC correlates strongly with BMI in pregnancy up to a gestation of 30 weeks in women attending Metro West maternity services. In low-resource settings, the simpler MUAC measurement could reliably be substituted for BMI to assess nutritional status.