It aims to validate the International Fetal and Newborn Growth Consortium for the 21st century (Intergrowth-21st) standards for gestational weight gain (GWG) and create new recommendations for first trimester normal and overweight women. GWG recommendations currently used in SUS have not been properly tested or validated, thus the project might improve prenatal nutritional care and reduce post gestational weight retention.
This project was divided into seven stages. In the first stage, a systematic review was conducted in national and international bibliographic databases to identify studies conducted in Brazil from 1990 onward. In the second stage, data cleaning of SISVAN and the creation of an algorithm, including the assessment of implausible values, was performed. Next, a descriptive analysis of the cleaned data of pregnant women registered in the system was carried out. In the fourth stage, the agreement between self-reported pre-pregnancy weight and the weight measured during the first trimester of pregnancy was evaluated. For this stage, data from CONMAI and the Food and Nutrition Surveillance System (SISVAN) were used. In the fifth stage, Brazilian gestational weight gain curves were created. For these curves, only women without pre-existing or pregnancy-related illnesses, who delivered children with appropriate weight for gestational age at term, were included. To assess the external validity of the curves, data from the “Born in Brazil” study conducted between 2011 and 2012 were utilized. A workshop was organized to discuss the new instrument, and consultations with professionals and primary care managers were also conducted. In the sixth stage, the national curves were compared to several international curves developed in recent years. In addition to visual comparisons, the quality of fit for each curve was evaluated against the “Born in Brazil” data. Finally, in the seventh stage, provisional recommendations for GPG were established based on the z-scores and percentiles of the curves, considering the occurrence of adverse child outcomes and using the non-inferiority margin method.
New gestational weight gain (GWG) curves for Brazilian women have been developed, focusing exclusively on those without pre-existing or pregnancy-related illnesses who delivered full-term neonates appropriate for gestational age. These curves reflect the GWG patterns in apparently healthy women with favorable perinatal outcomes.
An algorithm was created to clean the SISVAN database for pregnant women, which involved conducting consistency analyses, identifying outliers, and refining the data before determining how GWG would be calculated in the curves. Additionally, the study assessed the agreement between self-reported pre-pregnancy weight and measured weight during the first trimester among Brazilian women. The impact of using each of these estimates on pre-pregnancy body mass index (BMI) classification was also evaluated.
Since self-reported pre-pregnancy weight is the most commonly available measure during prenatal care, it was used in our curves. The results indicate that self-reported pre-pregnancy weight can effectively be used to calculate both BMI and GWG when early pregnancy weight measurements are unavailable.
Gestational weight gain (GWG) is a significant aspect of pregnancy, as it is a modifiable factor closely linked to adverse maternal and neonatal outcomes. Consequently, health professionals often monitor GWG. However, the current recommendations used in the Brazilian Unified Health System (SUS) have not been properly tested or validated. These guidelines have a limited ability to predict negative perinatal outcomes related to GWG and incorrectly classify excessive weight gain as “adequate.” This misclassification may be contributing to the obesity epidemic in the Brazilian population.
This research is crucial for public policies aimed at improving maternal and child health. The project developed new curves for monitoring gestational weight gain (GWG), based on national studies, which have been incorporated into 5 million prenatal booklets distributed across Brazil. These curves are designed to reflect the reality of Brazilian women and will assist both health professionals and pregnant women in tracking nutritional status during pregnancy, potentially improving maternal and child nutrition in the short and long term. To support health professionals, tools such as an offline calculator in Excel and a free online monitoring tool developed in R allow for classification and monitoring of pregnant women according to the new curves. Additionally, an Android/iOS app was created for GWG monitoring, providing recommendations and guidance based on the Brazilian Food Guide.
The next steps for this project include the following:
1. Establish a linkage among SISVAN data, the National Birth System, and the National Mortality System. This will enhance our ability to evaluate the effectiveness of the curves in predicting outcomes, including infant mortality.
2. Develop recommendations for gestational weight gain (GWG) based on available outcomes and the trade-offs between maternal and infant health.
3. Conduct a Delphi panel of experts to recommend a new GWG policy.
4. Create a mobile app with updated charts and nutritional guidance.
5. Develop an interactive dashboard for Brazilian states to improve the quality of public reports generated from routine prenatal care data.
6. Disseminate these methods to other countries and across life stages, such as adolescence.