Percent of non-pregnant women of reproductive age who have a high body mass index (BMI>25)
The percent of non-pregnant women ages 15 to 49 who have a body mass index (BMI) that is equal to or greater than 25 kg/m2. BMI is the ratio of weight to height squared (kg/m2) and a high BMI measures overweight, and/or obesity in non-pregnant women.
This indicator is calculated as:
(Number of non-pregnant women ages 15 to 49 with a BMI ≥25 / Total number of non-pregnant women between the ages of 15-49) x 100
BMI is calculated as: Weight in kilograms / (Height in meters)2
There are numerous tools (charts, websites, and computer applications) available to calculate BMI. The standard cut-off for overweight in non-pregnant, non-lactating women aged 15-49, determined by WHO (2004) and used by the Institute of Medicine (IOM, 2009) is a BMI of ≥25.
Further refinements in BMI levels of are:
- Overweight ≥25.00
- Pre-obese 25.00 – 29.99
- Obese ≥30.00
- Obese class I 30.00 – 34.99
- Obese class II 35.00 – 39.99
- Obese class III ≥40.00
For the full BMI reference table, see WHO Global Database for BMI, 2010.
Measurement of weights and heights of non-pregnant women of reproductive age. Data may be disaggregated by age grouping, levels of overweight and obesity based on WHO cutoffs, by lactation status for postpartum women, and, where data are available, by relevant socioeconomic and demographic factors such as education, income, and urban/rural residence.
Population-based surveys; surveillance systems; health facility records
A well-accepted measure of weight status, BMI is a self-contained ratio highly correlated with weight-for-height that does not require reference tables for interpretation. Although this indicator specifies non-pregnant women, BMI during early pregnancy also is commonly used to identify women who need to gain more or less weight in order to improve pregnancy outcomes. This indicator relates to two of the Millennium Development Goals: #4. Reduce child mortality; and #5. Improve maternal health.
Overweight and obesity is a growing problem worldwide and part of a “double burden” of health concerns stemming from the co-existences of under- and overnutrition in many regions. While rates of underweight children in Africa have not fallen between 1990 and 2010, rates of overweight have doubled (WHO, 2010). The highest rates of overweight for women are found in Central America (67%) and the Federated States of Micronesia (62%). (Note: For regional and national BMI surveillance data, see WHO Global Database for BMI.
Overnutrition is a form of malnutrition and, depending on the types and amounts of foods consumed, can be associated with diets high in processed calorie-dense foods, yet deficient in key nutrients, vitamins and minerals. Overweight adolescent girls and women are at increased risk for a number of chronic diseases including cardiovascular disease, type 2 diabetes, hypertension, stroke, and some cancers in addition to elevated risk for pregnancy complications and poor birth outcomes. Based on a meta-analysis from developed and developing countries, MacDonald et al. (2010) found that overweight and obese women have increased risks of preterm birth. Maternal obesity has been found to be associated with increased incidence of pre-eclampsia, gestational hypertension, macrosomia, stillbirth, induction of labor and caesarean delivery (Bhattacharya, et al., 2007). Higher BMI among women with short stature is a risk factor for pregnancy complications and the need for assisted delivery (Cnattingius et al., 1998).
BMI may present difficulties to some field workers in service delivery programs because of the mathematical calculations required. Tools (e.g., tables, wheels) have been developed to assist with these calculations and, more recently, website, computer, and phone applications are available to calculate BMI. Rapid changes in anthropometric measures as a result of the adolescent growth spurt complicate assessing the nutritional status of those below 18 years of age (i.e., it increases the variance in BMI). Despite this caveat, BMI is recommended for use with adolescents.
Because BMI varies with body proportions or the Cormic index (sitting height divided by standing height), some have argued that data on sitting height should be collected where possible and that the BMI should be adjusted for the Cormic index. However, others consider this adjustment to be impractical, given that the calculation of BMI itself is methodologically challenging to some field workers.
nutrition, safe motherhood (SM)
Bhattacharya, Sohinee, Campbell, DM, Liston WA, and Bhattacharya Siladitya, Effect of Body Mass Index on pregnancy outcomes in nulliparous women delivering singleton babies, BMC Public Health 2007, 7:168 doi:10.1186/1471-2458-7-168.
Cnattingius R, Cnattingius S, Notzon FC, Obstacles to reducing cesarean rates in a low-cesarean setting: the effect of maternal age, height, and weight. Obstet Gynecol. 1998 Oct;92(4 Pt 1):501-6.
MacDonald SD, Han Z, Mulla S, Beyene J, Overweight and obesity in mothers and risk of preterm birth and low birth weight infants: systematic review and metananlysis, BMJ 2010:341:c3428.
WHO Global Database for Body Mass Index, http://apps.who.int/bmi/index.jsp?introPage=intro_3.html.
WHO, 2010, A Review of Nutrition Policies: Draft Report, Geneva: WHO.
WHO, Maternal anthropometry and pregnancy outcomes: A WHO Collaborative Study, World Health Organ Suppl 1995: 73:32-37.