MTHFR and folate deficiency: Expert consensus in China suggests that for women planning pregnancy who are at high risk of folate deficiency-related birth defects and have MTHFR gene TT or CT genotypes (confirmed by genetic testing), it is recommended to take multivitamins containing 0.8–1 mg of folic acid daily, starting at least 3 months before conception (Chen et al., 2024).