What is Optimal pre-pregnancy BMI cut-off point for pregnant women with maternal cardiometabolic conditions?

The body mass index (BMI) is a widely utilized measure for assessing the nutritional status of populations, determined by measuring an individual’s weight and height. The World Health Organization (WHO) has proposed BMI thresholds of 30.0 kg/m2 to classify individuals as obese and 25.0 kg/m2 for categorizing adults as overweight.

Similarly, the Institute of Medicine (IOM) guidelines categorize body weight based on BMI values, classifying women as overweight (25.0-29.9 kg/m2 ) or obese (30.0 kg/ m2 ), regardless of age, parity, smoking history, or ethnic background. These BMI categories have been utilized to establish recommended guidelines for gestational weight gain. However, it remains uncertain whether these recommendations from the WHO and IOM adequately reflect the risk of adverse maternal and perinatal outcomes among pregnant women. Moreover, a rise in the BMI of pregnant women is linked to an elevated risk during pregnancy, including cesarean sections (both elective and emergency), gestational diabetes, postpartum hemorrhage, preeclampsia, preterm rupture of membranes, and other associated issues.

Additionally, infants born to mothers with higher BMI values face an increased likelihood of scoring below 7 on the 5-minute APGAR scale. Therefore, using traditional adult BMI to predict adverse maternal or fetal outcomes among pregnant women has shown inaccuracies. Consequently, this study aimed at suggesting new BMI cut-off points based on cardiometabolic conditions in pregnancy using a low-risk outpatient sample. The objective is to identify pregnant women at risk early on, allowing them to receive adequate prenatal care, ultimately leading to improved maternal and perinatal outcomes.

In this prospective study, singleton pregnant women from the fetal medicine service of the Brazilian Unified Health System were included. The pregnancy, perinatal, and newborn data were obtained from the clinical medical records. Maternal anthropometry included an assessment of weight and height and the prepregnancy BMI evaluation categorized according to the World Health Organization cut-off points. The area under the curve and confidence interval values from receiver operator curves were generated to identify the optimal cut-off points using prepregnancy BMI with better sensitivity and specificity.

Data on 218 pregnancies were analyzed, with 57.9% (n = 124) being classified as overweight/obese, 11% (n = 24) with GDM, 6.9% (n = 15) with preeclampsia, and 11.0% (n = 24) with gestational hypertension. The BMI cut-off points for predicting cardiometabolic conditions were 27.52 kg/m2 (S: 66.7%; E: 63.8%) for women with GDM; 27.40 kg/m2 (S: 73.3%; E: 62.4%; S: 79.2%; E: 64.9%; S: 70.3%; E: 66.3%) for women with preeclampsia, gestational hypertension, and gestational hypertension plus preeclampsia, respectively; and 27.96 kg/m2 (S: 69.6%; E: 65.6%) for women with preeclampsia plus GDM.

The main finding was that the best prepregnancy BMI threshold associated with cardiometabolic conditions during pregnancy was around 27 kg/m2 . Sensitivity, considered the most significant parameter in diagnostic evaluation, achieved an approximate rate of 80% for gestational hypertension and 73% for preeclampsia outcomes. Furthermore, the ROC curve performance achieved a high AUC for gestational hypertension using a prepregnancy BMI threshold of 27.4 kg/m2 .

In summary, the present study suggests that the use of adult BMI thresholds among pregnant women may not be universally applicable to all scenarios. Instead, adopting 27 kg/m2 as a cut-off point threshold appears to be more effective in predicting adverse pregnancy-related outcomes, achieving a better balance between sensitivity and specificity. This allows for early identification of pregnant women at risk for common metabolic outcomes of pregnancy with superior accuracy. Ultimately, early implementation of rigorous clinical and nutritional care will lead to better maternal and perinatal outcomes.

Source: Renata O. Neves , 1 Alexandre da S. Rocha , 2 Bruna O. de Vargas; Hindawi Journal of Pregnancy Volume 2023, Article ID 6669700, 7 pages https://doi.org/10.1155/2023/6669700