Better diet may reduce foetal growth restriction, pregnancy-related hypertension risk

A high-quality diet during pregnancy may reduce the risk of foetal growth restriction (FGR) and hypertensive disorders of pregnancy, according to a study presented at SMFM 2022.

The analysis was based on a prospective study of 762 pregnant women who completed the National Institutes of Health (NIH) Diet History Questionnaire II (DHQ-II) in the third trimester of their singleton pregnancies or within 3 months of delivery. Diet quality was determined by the US Department of Agriculture’s Healthy Eating Index (HEI), with higher scores indicative of healthier diet, as per the US Government’s Dietary Guidelines for Americans. Non-hospital deliveries, foetal anomalies, and IVF pregnancies were exclusion criteria.

The mean HEI score among the participants was 60, with 17 and 83 percent (n=128 and 634, respectively) having a high and low HEI score, respectively (scores of ≥70 and <70, respectively). The mean age of women in the high and low HEI groups were 30.33 and 27.98 years, respectively, and 75.0 and 42.9 percent, respectively, were White. Baseline BMI was 25.08 and 29.59 kg/m², respectively, 13.3 and 39.7 percent were classified as obese, and mean weight gain during pregnancy was 28.45 and 25.33 lb, respectively.

After adjusting for obesity and chronic hypertension, the risk of FGR, defined as estimated foetal weight <10^th percentile at time of delivery, was 67 percent lower among those with a high vs low HEI score (4.7 percent vs 13.9 percent; adjusted risk ratio [adjRR], 0.33, 95 percent confidence interval [CI], 0.13–0.68; p=0.006). [SMFM 2022, abstract 26]

Participants with a higher HEI score also had a 54 percent lower risk of developing hypertensive disorders of pregnancy compared with those with a lower HEI score (8.6 percent vs 21.9 percent; adjRR, 0.46, 95 percent CI, 0.24–0.79). These findings pertained to both gestational hypertension (4.7 percent vs 13.0 percent; adjRR, 0.42, 95 percent CI, 0.17–0.87) and preeclampsia (3.9 percent vs 12.8 percent; adjRR, 0.36, 95 percent CI, 0.13–0.80).

The incidence of gestational diabetes was comparable between those with higher and lower HEI scores (2.3 percent vs 6.0 percent; adjRR, 0.58, 95 percent CI, 0.14–1.62), as was the risk of delivering infants who were large for gestational age (7.0 percent vs 7.7 percent; adjRR, 0.95, 95 percent CI, 0.44–1.83), unplanned Caesarean delivery (18.0 percent vs 13.9 percent; adjRR, 1.49, 95 percent CI, 0.95–2.25), and preterm delivery before 37 weeks (88.3 percent vs 88.0 percent; adjRR, 1.25, 95 percent CI, 0.70–2.05).

“Poor nutritional quality can be associated with excess maternal weight gain and associated complications,” said study author Dr Xiao-Yu Wang from the Washington University School of Medicine in St. Louis, Missouri, US.

“However, there are limited studies that assess the effect of nutritional quality on perinatal outcomes and there are no formal guidelines on how to assess nutritional quality,” he added.

“[This study demonstrated that] a high-quality diet is associated with decreased risk of FGR and hypertensive disorders of pregnancy,” pointed out Wang and co-authors.

Wang highlighted that socioeconomic factors, such as access and affordability of high-quality nutritional options, may play a role in nutritional quality, both on the individual and systemic level, and suggested the need for future research into assessing these factors.

“What this research [also] shows us is that HEI is another tool we can use, especially in collaboration with dieticians and nutritionists, to counsel our patients to help improve pregnancy outcomes. HEI also puts the power into the hands of the patient because the tool reveals risk factors that a patient can modify to help create a healthier pregnancy and a better pregnancy outcome,” he concluded.