Nutrition, supplementation and exercise in pregnancy

The booking visit is where a single conversation prevents a neural tube defect, a vitamin-D-deficient third trimester, and a postpartum weight that never returns. The evidence here is unusually clean and unusually actionable — folate, iodine, exercise and weight gain all change outcomes — so the examiner expects you to know the doses and the BMI targets by heart. This topic is that conversation, structured. RANZCOG frames it in C-Obs 25 (Vitamin and Mineral Supplementation) and C-Obs 62 (Exercise During Pregnancy); the PubMed-backed evidence follows.[11][2]

Overview and what to give everyone

Split supplementation into three tiers — routine for all, targeted to risk, and to be avoided — and you will not over-prescribe or under-prescribe.[11]

• Routine for every woman — folic acid in the peri-conceptional period, and iodine throughout pregnancy and breastfeeding.[1][3]
• Targeted to risk — iron, vitamin D, vitamin B12 (vegetarians and vegans), and calcium for low intake.[8][10]
• To be avoided — high-dose vitamin A (retinol), unregulated herbal products, and any supplement exceeding safe upper limits.[11]

References12Show ledgerHide ledger

1. [1]Barry MJ, Nicholson WK, Silverstein M, et al. Folic Acid Supplementation to Prevent Neural Tube Defects: US Preventive Services Task Force Reaffirmation Recommendation Statement JAMA, 2023.PMID 37526713
2. [2]MRC Vitamin Study Research Group Prevention of neural tube defects: results of the Medical Research Council Vitamin Study Lancet, 1991.PMID 1677062
3. [3]Obican SG, Jahnke GD, Soldin OP, Scialli AR Teratology public affairs committee position paper: iodine deficiency in pregnancy. Birth Defects Res A Clin Mol Teratol, 2012.PMID 22903940
4. [4]American College of Obstetricians and Gynecologists ACOG Committee Opinion Number 804: Physical Activity and Exercise During Pregnancy and the Postpartum Period Obstet Gynecol, 2020.PMID 32217980
5. [5]American College of Obstetricians and Gynecologists ACOG CommitteeOpinion No. 462: Moderate caffeine consumption during pregnancy. Obstet Gynecol, 2010.PMID 20664420
6. [6]Weng X, Odouli R, Li DK Maternal caffeine consumption during pregnancy and the risk of miscarriage: a prospective cohort study Am J Obstet Gynecol, 2008.PMID 18221932
7. [7]American College of Obstetricians and Gynecologists ACOG Committee opinion no. 548: weight gain during pregnancy. Obstet Gynecol, 2013.PMID 23262962
8. [8]Cantor AG, Holmes R, Bougatsos C, et al. Screening and Supplementation for Iron Deficiency and Iron Deficiency Anemia During Pregnancy: Updated Evidence Report and Systematic Review for the US Preventive Services Task Force JAMA, 2024.PMID 39163033
9. [9]Peña-Rosas JP, De-Regil LM, Garcia-Casal MN, Dowswell T Daily oral iron supplementation during pregnancy Cochrane Database Syst Rev, 2015.PMID 26198451
10. [10]De-Regil LM, Palacios C, Lombardo LK, Peña-Rosas JP Vitamin D supplementation for women during pregnancy. Cochrane Database Syst Rev, 2016.PMID 26765344
11. [11]Cooper KM, Szymanski LM, David PS, Allen SV, Breitkopf DM Prepregnancy Care and Counseling: A Review. JAMA, 2026.PMID 42008245
12. [12]Zimmermann MB Iodine deficiency in pregnancy and the effects of maternal iodine supplementation on the offspring: a review Am J Clin Nutr, 2009.PMID 19088150