A recent study published European Journal of Clinical Nutrition examined the relationship between increasing trends toward a plant-based diet and increased risk of excessive or insufficient gestational weight gain among Iranian pregnant women.
Gestational weight gain is an important health indicator for maternal and fetal health during pregnancy. It is a physiological response during pregnancy due to gestational fat accumulation and fetal development. It is strongly correlated with fetal development and infant health outcomes, with studies showing that inadequate gestational weight gain often results in low birth weight infants, as well as intrauterine growth retardation. On the other hand, excessive gestational weight gain increases the risk of preterm delivery and predisposes the child to childhood obesity.
Gestational weight gain can be regulated by maternal diet, and recent studies have shown that the macronutrient composition and energy content of the maternal diet are strongly associated with the degree of weight gain during pregnancy. Furthermore, recent research in nutritional epidemiology has focused more on analyzing dietary patterns rather than single nutrient intake as a predictor of better health outcomes. As vegetarian and plant-based diets are increasing in popularity, particularly among young women, understanding the effects of such diets on gestational weight gain is vital.
About the study
In the current study, researchers calculated three dietary indices—the plant-based dietary index, the healthy plant-based dietary index, and the healthy plant-based dietary index—by assigning separate scores to healthy and less healthy diet groups that were plant-based and animal-based. -based food groups. They examined a prospective cohort of Iranian pregnant women to understand the risk of excessive or insufficient gestational weight gain and the relationship between these dietary indicators.
This study was part of the Persian Birth Cohort Study conducted in five Iranian districts to gather knowledge and scientific evidence for policy making regarding various developmental aspects of the disease by examining the influence of lifestyle, socioeconomic factors, and environment on pregnancy outcomes.
The present study recruited women from healthcare centers in Semnan city from 2018 to 2020. Women who have lived in the city for at least one year, are in the first trimester of pregnancy, and want to give birth to their child. City hospitals were eligible to participate in the study. Pregnancies that ended in normal and cesarean delivery were included in the study, women undergoing hormone therapy or with hormonal disorders or twin pregnancies were excluded from the study.
Dietary indices were calculated by assigning different scores to different types of food and participants’ dietary habits were assessed using a food frequency questionnaire containing 90 items. Maternal weight was measured after each trimester and before delivery, and gestational weight gain was calculated by subtracting the first-trimester weight from the last measured weight before delivery. Prepregnancy weight gain was classified as adequate, excessive, or insufficient, based on body mass index before pregnancy.
Information on demographic characteristics, disease history, education level, physical activity level, vitamin supplementation and other variables including socioeconomic factors were obtained during the interview.
The results show that increased adherence to plant-based dietary patterns reduces the risk of inadequate gestational weight gain. The association between plant-based dietary indices and inadequate gestational weight gain was negative. However, no significant association was observed between the other two dietary indices and insufficient gestational weight gain. Excessive gestational weight gain did not show any association with dietary indices.
Studies have shown that, as recommended by the American Dietetic Association, a higher intake of fruits, legumes, vegetable oils and vegetables with fish reduces the risk of inadequate weight gain during pregnancy. The researchers believe that the lack of any observed association between dietary indicators and excess gestational weight gain may be due to the small study population.
A possible mechanism by which plant-based diets may help control gestational weight gain is based on the fiber content of plant-based diets. The high dietary fiber content of vegetables, fruits, nuts, and cereals regulates appetite by increasing the release of satiety hormones, which help control body weight. It helps regulate postprandial insulin and subsequent fat oxidation.
Overall, the results indicated that increased adherence to a plant-based diet was associated with a lower risk of inadequate gestational weight gain. No association was observed between plant-based dietary indices and excessive gestational weight gain, and further studies in larger cohorts are needed to understand the association between dietary patterns and gestational weight gain.