Importance of Prenatal Multivitamin Breakdown of Vitamins

Variable based on ingredient and formulation, for 5-6 weeks within the preconceptional period

• • • A 2021 Australian systematic review of guidelines for complementary medicines and therapies found many of the guidelines to be recommending the following common ingredients in prenatal multivitamins: folic acid, vitamin D, iodine, iron, vitamin B6, and vitamin B12. (Ee 2021)
    • A 2017 systematic review (SR) and meta-analysis (MA) of multivitamin supplementation in high-income countries examined 98,926 females in 35 studies, finding reduced relative risk of small gestational age by 23%, neural tube defects by 33%, cardiovascular defects by 17%, urinary tract defects by 40%, and limb deficiencies by 32%. Due to the difficulty of having an ethical placebo group in studies on pregnancy, of the 35 studies, only four were randomized controlled trials. (Wolf 2017)
  • Folic acid
  • • • A 2021 SR and MA of 39 studies examining folic acid supplementation concluded that folic acid was associated with a positive impact on an offspring’s neurodevelopmental outcomes, including improved intellectual development and reduced risk of autism traits, ADHD, behavioral, and language problems. (Chen 2021)
      • A Cochrane review found risk of neural tube defects was lowered at a dose of > 400 µg per day. (De-Regil 2015)
  • Iodine
  • • • A Cochrane review found RCTs showing iodine supplementation reduced the risk of postpartum hyperthyroidism by 68%. (Harding 2017)
      • Iodine content in multivitamin products studied was typically found to be sufficient (> 150 μg). (Leung 2009)
  • Iron
  • • • Many women, even in developed countries, may be at risk of low iron status. A cohort study found that 68-82% of pregnant Australian females were not meeting the recommended daily intake of iron. (Livock 2017).
      • A 2015 Cochrane review found preventative iron supplementation reduced the risk of maternal anemia at term by 70%, iron-deficiency anemia at term by 67%, and iron deficiency at term by 57%. This Cochrane review found moderate-quality evidence of a borderline significant reduction in preterm babies of 7%. (Peña-Rosas 2015)
      • The same Cochrane review found no significant differences in effectiveness or likelihood of side effects for daily vs. weekly dosing of iron. (Peña-Rosas 2015) 
  • Vitamin B12
  • • • A 2021 SR of complementary medicines and therapies in clinical guidelines in pregnancy found no consistent recommendations for B12, except four organizations recommending routine supplementation for vegetarians and vegans and two recommending the intervention after screening for deficiencies. (Ee 2021)
      • The lowest quartiles in three different Irish cohorts had 2-3x the risk of neural tube defects versus the highest quartiles. To reduce neural tube defects, the authors recommended vitamin B12 levels of at least >221 pmol/L (>300 ng/L) prior to conception. (Molloy 2009)
  • Vitamin B6
  • • • A 2021 SR of complementary medicines and therapies in clinical guidelines in pregnancy found five guidelines recommended routine supplementation with vitamin B6, for its moderate-quality evidence for nausea and vomiting and safety. (Ee 2021)
      • 20-80 mg of vitamin B6 daily was found to be effective for nausea and vomiting in pregnancy in this 2020 SR. (Khorasani 2020)
  • Vitamin D
  • • A 2019 Cochrane review found a reduced relative risk of pre-eclampsia by 52%, gestational diabetes by 49%, low birthweight by 45%, and may reduce risk of severe postpartum hemorrhage by 32%. (Palacios 2019)
    • A 2021 SR of complementary medicines and therapies in clinical guidelines in pregnancy found three regulatory bodies recommending vitamin D at 400 IU to all pregnant women, and four organizations recommended over 1000 IU if a deficiency of less than 50 nmol/L of 25-hydroxyvitamin D was found. (Ee 2021)