Table 3 Summary of results from North American observational studies on diet and gestational diabetes

Bao W et al. 2017 [49]

USA- - North America

n: 15225

cohort

pregnant women aged 24–44 years from the Nurses’ Health Study II cohort, 1991–2001

pre pregnancy vitamin D intake

No association

Li M. et al. 2019 [50]

USA - North America

n: 14553

cohort

pregnant women aged 24–44 years from the Nurses’ Health Study II, 1991–2001.

pre pregnancy food folate intake

Adequate total folate intake (‡400 mg/day) RR = 0.83; 95% CI 0.72–0,95, p = 0.007)

Shin D. et al. 2015 [10]

USA- North América

n:253

cohort

pregnant women (16–41 years) included in the National Health and Nutrition Examination Survey (NHANES) 2003–2012. Gestational age of 20 weeks.

pregnancy dietary patterns

“High refined grains, fats, oils and fruit juice” pattern: OR = 4.9; 95% CI 1.4–17.0, p-trend: 0.007; “high nuts, seeds, fat and soybean; low milk and cheese” pattern: OR = 7.5; 95% CI 1.8–32.3, p-trend: 0.009; “high added sugar and organ meats; low fruits, vegetables and seafood” pattern: OR = 22.3; 95% CI 3.9–127.4, p-trend: < 0.0001

Osorio-Yáñez Citlalli et al. 2017 [51]

USA - North America

n: 3414

cohort

pregnant women < 20 weeks of gestation who attending prenatal care clinics affiliated with the Swedish Medical Center and Tacoma General Hospital in Seattle and Tacoma, 1996–2008

calcium and dairy products intake

Calcium intake: RR = 0·58; 95% CI 0·38–0·90; p = 0·015; low fat dairy product RR = 0,57; 95% CI: 0,32–1,02 p = 0,032; whole grains RR: 0,61; 95% CI: 0,39- 0,95, P = 0·019

Darling AM et al. 2016 [52]

USA, Canada - North America

n: 7229

cohort

pregnant women from the Slone Epidemiology Center Birth Defects Study, in the United States and Canada, 1998–2008

pre-pregnancy iron intake

Preconceptional dietary heme-iron 2.53; 95% CI: 1.70–3.78, p-trend: 0.02; preconceptional dietary non-heme iron OR = 0.53; 95% CI: 0.34–0.83, p-trend: 0.13

Chen Z et al. 2021 [53]

United States - America

n: 14926

cohort

Women from the Nurses’ Health Study II, 1991–2001

prepregnancy Plant-based diet index (PDI)

PDI: Q5 compared with Q1: RR 0.70 95% CI 0.56–0.87 ptrend = 0.0004. hPDI: the RR 0.75 95% CI 0.59–0.94, ptrend = 0.009. uPDI was not associated

Lindsay KL, et al. 2022 [54]

United States - America

n: 7997

cohort

women > 13 years old who came from eight U.S. medical centers between 2010 and 2013.

pregnancy and prepregnancy alternative healthy eating index (pAHEI) - 2010

higher adherence to an alternative healthy index (pAHEI): aOR = 0.986 95% CI = 0.973–0.998 p = 0.022