The double burden of malnutrition is a public health concern. The prevalence of anemia In Mexican women of reproductive age is 22% and around 75% present overweight or obesity. The joint prevalence of anemia and overweight or obesity in women of reproductive age is 10%, but little is known about the combined condition in pregnant women. Pregnancy is a vulnerable period as women have increased iron requirements, in addition, needs may be even higher in the presence of obesity, since inflammation impairs iron absorption. The aim of this study is to estimate the association between weight gain, and the probability of developing anemia.


In 144 pregnant women from a birth cohort (MAS-LACTANCIA) in Mexico, was obtained information about pre-pregnancy characteristics, and by trimester of body mass index (BMI, kg/m2) gain and anemia (hemoglobin <110 g/L) from medical records. Random-effects logistic regression was estimated for the probability of having anemia in the second or third trimester according to BMI gain. The model was adjusted for age, previous pregnancies and pre-pregnancy BMI (self-reported).


Fifty percent of the participants were overweight before pregnancy (mean BMI 25.5kg/m2 (SD 3.8)) and 72.5% remained overweight by the last week of gestation, with a mean BMI increase of 2.9kg/m2 (SD 2.1). During pregnancy, anemia was present in 23% of the participants, and the joint prevalence of overweight and anemia was 12%. An increase of 1kg/m2 during pregnancy increased the probability of anemia by 19% (CI 95% 1.03, 1.51)


We demonstrated an increased risk of developing anemia with increasing weight gain. This may be due to either obesity-related inflammation which may lead to reduced dietary iron absorption, or to an energy-rich and micronutrient(iron)-poor diet. Future studies should focus on understanding the pathways and consequences for the mother and offspring affected by the joint prevalence of obesity and anemia and finding ways to prevent those conditions.