First Author’s Name

Year/Country/ Study design

Sample size

Inclusion/Exclusion Criteria


Chen, Q.

2019/China/ Case-Control

9556: 1464 (15.3%) GDM cases and 8092 (84.7%) non-GDM controls

Inclusion criteria: women aged 18 years or older with gestational age of 20 weeks or more and without mental illness

Exclusion criteria: previous DM, Gestational age < 24

Higher folate and potassium level in the vitamin supplements increased the risk of GDM.

Increased FA level aggravates the effects of vitamin B12 deficiency and exacerbates insulin resistance.

Cheng, G.

2019/China/ Cohort

950 (GDM cases were 10.2%)

Inclusion criteria: infants had health care records in the CHMIS; mothers and infants’ guardians agreed to participate and signed the written informed consents; and mothers took FA supplements at a dose of 400 mcg/day before, and during, pregnancy.

Exclusion criteria: mothers had a history of mental illness or brain disease, diabetes before pregnancy; multiple pregnancy; congenital abnormalities in the newborn

FA supplementation for ≥3 months before pregnancy was associated with an increased risk of GDM (aRR: 1.72; 95% CI: 1.17 - 2.53)

Huang, L.

2019/China/ Cohort

326: 33 (10.1%) had GDM


After adjusting for confounding factors, the aOR of GDM comparing taking folic acid for >90 days with taking folic acid for ≤60 days was 3.45 (95% CI: 1.01, 11.8)

Li, Q.

2019/China/ Cohort

4,353: 8.6% had GDM

Exclusion criteria: those with diabetes, multiple pregnancies, abortions, without reliable OGTT or folic acid supplementation values

FA supplement use >800 mg/day from pre-pregnancy through mid-pregnancy was associated with the development of GDM

Zhang, H.

2019/China/ Cohort

5165: 604 (11.7%) had GDM

Exclusion criteria: women with one of the following

Conditions: pre-existing type 1 and type 2 DM or GDM, thyroid disease, hypertension, asthma and systemic lupus erythematosus.

First trimester exposure to ai polluted with SO2 increased the risk of GDM, especially if between the 4th and 10th weeks of gestation, and if using FA supplements.

Zhu, B.

2019/China/ Cohort

1938: 249 (12.8%) had GDM

Inclusion criteria: Women who had either used FA supplements or never used any vitamin supplements

Higher risk of GDM was found with daily FA supplementation during the first trimester (aOR = 2.25 [95% CI 1.35 - 3.76])