Clinical Context

The Centers for Disease Control and Prevention reports that US pregnancy-related mortality has increased steadily during the past 30 years, with significant racial and age disparities. Adverse pregnancy outcome (APOs) are leading risk factors for maternal morbidity/mortality, mandating APO prevention.

Poor diet quality is common among US women periconceptionally, and dietary patterns seldom change significantly from prepregnancy to early pregnancy. Periconceptual diet is therefore an important potential target for reducing APOs. Mediterranean diet has been linked to health and longevity and might help prevent APOs.

Study Synopsis and Perspective

Women in the United States who followed a Mediterranean-style diet (heavy on fresh foods, fish, and olive oil) around the time of conception had lower risk of developing a pregnancy complication, results of a large new study suggest.

The study included 7,798 women who had not given birth before. The group was geographically, racially, and ethnically diverse.

Researchers led by Nour Makarem, PhD, from the Department of Epidemiology, Columbia University, New York, published their results in JAMA Network Open.

“Generally higher intakes of vegetables, fruits, legumes, fish, and whole grains and lower intakes of red and processed meat were associated with lower risk of APOs,” the authors write.

The investigators found that women in the study, who were part of the Nulliparous Pregnancy Outcomes Study: Monitoring Mothers-to-Be, which enrolled 10,038 women between October 1, 2010, and September 30, 2013, and scored high on adherence to a Mediterranean diet, had a 21% lower risk of developing any APO than those who had low adherence. And the better the adherence, the lower the risk for adverse outcomes, especially preeclampsia or eclampsia and gestational diabetes, the researchers write.

The research team also studied how following the diet correlated with gestational high blood pressure, preterm birth, delivery of a small-for-gestational-age infant, and stillbirth.

Women were scored on consumption of 9 components: vegetables (excluding potatoes), fruits, nuts, whole grains, legumes, fish, monounsaturated to saturated fat ratio, red and processed meats, and alcohol.

There were no differences in adverse pregnancy outcomes by race, ethnicity, or the woman’s body mass index before pregnancy, but associations were stronger in the women who were aged 35 years or older, according to the article.

The authors point out that the women in the study had access to prenatal care at a large academic medical center during their first 3 months of pregnancy, so the study may actually underestimate the importance of the diet in the pregnancy outcomes.

Christina Han, MD, division director of maternal-fetal medicine at University of California, Los Angeles, who was not part of the study, said that the results make sense, as the researchers looked at the time of conception, which is a time that reflects the way a person chooses to live their life.

“We know that your health state as you enter pregnancy can significantly affect your outcomes for that pregnancy,” she said. “We’ve known for decades now that a Mediterranean diet is good for just about everybody.”

Dr Han said that although it is great that the researchers were able to confirm the benefit of the Mediterranean diet, it highlights inequity, as lower-income people are not as likely to be able to afford fresh fruits and vegetables and fish.

“This is a call to arms for our food distribution system to even out the big divide in what patients have access to,” Dr Han said.

She noted that most of the women in this study were married, non-Hispanic White, and had higher levels of education, which may make it hard to generalize these results to the general population.

A limitation of the study is that the women were asked to report what they ate themselves, which can be less accurate than when researchers record what is eaten in a controlled setting.

The researchers suggested a next step: “Long-term intervention studies are needed to assess whether promoting a Mediterranean-style diet pattern around the time of conception and throughout pregnancy can prevent APOs.”

Dr Makarem reported receiving grants from the National Institutes of Health and the American Heart Association outside the submitted work. One coauthor reported receiving grants from the Eunice Kennedy Shriver National Institute of Child Health and Human Development during the study. One coauthor reported receiving personal fees for serving on the board of directors for iRhythm and from fees paid through Cedars-Sinai Medical Center from Abbott Diagnostics and Sanofi outside the submitted work, and a coauthor reported serving as a clinical end point committee member for GlaxoSmithKline outside the submitted work. No other disclosures were reported. Dr Han has disclosed no relevant financial relationships.

JAMA Netw Open. 2022;5(12):e2248165.^[1]

Clinical Implications

• Greater Mediterranean diet concordance was significantly associated with lower APO risk.
• Intervention studies are needed to determine whether promoting a Mediterranean-style diet around the time of conception and throughout pregnancy could prevent APOs.
• Implications for the Health Care Team: In order to best counsel women on the impact of diet on pregnancy outcomes, members of the healthcare team should be aware of the accumulating evidence that the Mediterranean diet pattern may help preserve women’s health across the lifespan.

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