Percent of women who gain weight in the last two trimesters of pregnancy within the recommended range for their weight status

Percent of women who gain weight in the last two trimesters of pregnancy within the recommended range for their weight status

Percent of women who gain weight in the last two trimesters of pregnancy within the recommended range for their weight status

The percent of women who gain within the recommended kg/month range during the second and third trimesters of pregnancy for their weight status (underweight, normal weight, overweight or obese) based on pre-pregnancy or very early pregnancy body mass index (BMI) levels.  Recommended ranges for gestational weight gain (GWG) are based on the Institute of Medicine guidelines (IOM, 2009).

This indicator is calculated as:

(Number of women by weight category gaining in recommended kg/month range in second and third trimesters of pregnancy / Total number of pregnant women in weight category) x 100

The GWG ranges by pre-pregnancy BMI status are as follows:

Recommended GWG Ranges in Kg

Weight Status                 Weekly                   Monthly*              Total GWG

Underweight                   0.44 – 0.58             1.9 – 2.5              12.5 – 18.0

(BMI <18.5)

Normal Weight               0.35 – 0.50            1.5 – 2.1               11.5 – 16.0

(BMI 18.5 – <25)

Overweight                     0.23 – 0.33            1.0 – 1.4                7.0 – 11.5

(BMI 25 – <30)

Obese                              0.17 – 0.27           .75 -1.2                  5.0 – 9.0

(BMI 30+)

* The recommended monthly GWG ranges for the 2nd and 3rd trimesters were calculated by multiplying the weekly ranges by 4.3.

From: Weight Gain During Pregnancy: Reexamining the Guidelines  (IOM, 2009). The table is available online at  Also see Tumilowicz (2010) for use of the IOM tables for GWG recommendations for women with HIV based on the IOM guidelines.

BMI is calculated as:  Weight in kg / (Height in m)2

There are numerous tools (charts, websites, and computer applications) available to calculate BMI.

Measurement of BMI (height and weight) pre-pregnancy or early in first trimester of pregnancy and two or more recordings of weight after the third month of pregnancy. The repeated measures of weight during pregnancy may not be taken at even monthly intervals and will require interpolation based on the number of weeks or months between measurements in order to calculate and categorize by the recommended ranges.

Service statistics, antenatal care (ANC) cards, or other clinic-based records; samples of home or community-based records reviewed

This indicator measures weight gain during pregnancy, one of the most critical factors in determining both birth outcomes and maternal nutritional outcomes of pregnancy. Weight gain is particularly important for women who are underweight prior to pregnancy and for women who are pregnant during times of acute nutritional stress, such as famines or seasons of food scarcity.  Conversely, the prevalence of overweight has been increasing worldwide during the past two decades resulting in a “double burden” of health concerns stemming from the co-existence of under- and over-nutrition in many regions.  Given the rising numbers of overweight and obese women of reproductive age, recommended GWG for normal to overweight women and concerns with excess GWG need to be taken into consideration.  This indicator relates to three of the Millennium Development Goals: #1. Reduce poverty and hunger; #4. Reduce child mortality; and #5. Improve maternal health.

The 2009 IOM guidelines are based on observational studies which show that women who gain within the recommended range for their weight status had better pregnancy outcomes than those who did not.  Ranges are used for each of the weight categories given the imprecision of the estimates used to develop the guidelines, and they are intended to be used with good clinical judgment at the individual client level. Based on a systematic review of studies, strong associations were found between GWG below the IOM guidelines with preterm birth, decreased birthweight, fetal growth small for gestational age, and failure to initiate breastfeeding (Viswanathan et al., 2008; Siega-Riz et al., 2009) .

Weight gains above the IOM recommendations were associated with increased birthweight and fetal growth large for gestational age (LGA), as well as, postpartum weight retention (Siega-Riz et al., 2009).  In a prospective cohort study, Crane et al. (2009) found that for women with normal pre-pregnancy BMI, excess GWG was associated with increased rates of gestational hypertension, augmentation of labor, and LGA birthweight.  For overweight women, excess GWG was associated with increased rates of gestational hypertension and LGA birthweight, and for women who were obese or morbidly obese, excess GWG was associated with increased rates of LGA birthweight and neonatal metabolic abnormality.

This indicator reflects the importance of routine and high-quality ANC through multiple prenatal visits. Moreover, it focuses the attention and care of both the health worker and the woman on weight gain and healthy weight gain promotion rather than simply on determining maternal nutritional status at any one point in time.

The recommended ranges from the IOM guidelines were designed for use with American women and may be applicable for use with women in other developed countries.  They are not intended for use in areas where women are substantially shorter or thinner or where adequate obstetric services are unavailable.  There have not been recommended ranges by weight status set for developing country settings and the higher end of the IOM ranges may overestimate weight gain for women of short stature, particularly for women with severe stunting (<145 cm).  An earlier version of the indicator  ‘Percent of women who gain at least one kg per month in the last two trimesters of pregnancy’  did not differentiate by women’s weight status and set the threshold very low for underweight to normal weight women.  A WHO report (1995) indicated that a higher gain of 1.5-2.0 kg per month decreased LBW and intrauterine growth retardation.

The indicator requires not only an estimate of pre-pregnancy BMI, but additional calculations to interpolate the recommended GWG range for the interval between pregnancy weight measurements.  These calculations can be more complicated if the intervals vary and are not evenly spaced by month.

Another limitation with this indicator is that the population covered may not fully represent the intended population, because a very small percentage of women in many developing countries routinely attend ANC services. Frequent attendees tend to be either women with pregnancy complications or women of higher socio-economic and educational status. The difficulty in monitoring maternal nutrition during pregnancy is that many women do not get ANC, or they have only one visit late in the pregnancy.

A GWG indicator is most often used by organizations working in a limited geographic area. Evaluators face difficulty obtaining this information from large public health centers in developing countries that keep ANC records.

nutrition, newborn (NB), safe motherhood (SM)

Limiting food intake during pregnancy even for under and normal weight women is a gender-based, harmful cultural practice theoretically linked to the idea that limiting weight gain will reduce the infant’s head circumference, so that the birth will be less difficult.  More efforts are needed to educate husbands, mothers-in-law, and communities that particularly underweight and normal weight pregnant women must eat more, not less, and that nutritious foods benefit both mother and fetus and lead to better birth outcomes.

Crane JM, White J, Murphy P, Burrage L, Hutchens D., The effect of gestational weight gain by body mass index on maternal and neonatal outcomes. J Obstet Gynaecol Can. 2009 Jan;31(1):28-35.

Institute of Medicine and National Research Council, 2009, Weight Gain during Pregnancy: Reexamining the Guidelines, Eds: Kathleen Rasmussen and Ann Yaktine, Washington, D.C.: The National Academy Press.

Siega-Riz AM, Viswanathan M, Moos MK, Deierlein A, Mumford S, Knaack J, Thieda P, Lux LJ, Lohr KN. A systematic review of outcomes of maternal weight gain according to the Institute of Medicine recommendations: birthweight, fetal growth, and postpartum weight retention. Am J Obstet Gynecol. 2009 Oct;201(4):339.e1-14.

Viswanathan M, Siega-Riz AM, Moos MK, Deierlein A, Mumford S, Knaack J, Thieda P, Lux LJ, Lohr KN., Outcomes of maternal weight gain. Evid Rep Technol Assess (Full Rep). 2008 May;(168):1-223.

Tumilowicz A, 2010, Guide to Screening for food and Nutrition Services among adolescents and adults living with HIV, Washiggton, DC: FANTA/AED.

WHO, 2010, A Review of Nutrition Policies: Draft Report, Geneva: WHO.

WHO Global Database on Body Mass Index,

WHO, 1995, Maternal Anthropometry and Pregnancy Outcomes: A WHO Collaborative Study, Geneva: WHO.