• Brittany Darling

Second + Third Trimester Supplementation

Do I really need to keep taking prenatal supplements in my second and third trimester? The short answer is yes. And the long answer is....

The most commonly known nutrient when it comes to pregnancy is folate or its synthetic form, folic acid. It is taken in the preconception period and is recommend that you continue until 12 weeks of pregnancy to prevent neural tube defects. I highly recommend preconception testing to confirm you have serum folate >16nmol/L or RBC folate >906 nmol/L, as this is your actual body folate levels and is more important for NTD prevention than an actual dose of folate. Folate should always be taken with vitamin B12 as they both mask deficiency of each other.1

Beyond the first trimester, folate helps to keep homocysteine levels “normal”. Homocystine is an amino acid which is an indicator of how you are methylating. Methylation is important for genetic expression and DNA formation. High homocysteine and low folate concentrations are associated with low birth weight and preterm birth.

Iodine is another really important nutrient to maintain optimal maternal thyroid hormone production. Iodine is an essential mineral for the formation of thyroid hormones. Inadequate iodine in pregnancy is associated with mental retardation in the offspring. Please continue to supplement with 150 mcg of iodine daily. 2

A prenatal multi with a complex of vitamins and minerals is the best option for all trimesters of pregnancy. I do have a few further recommendations beyond the first trimester. It’s important to note that my recommendations in clinic are always based on your needs and budget. For many women, swallowing one multi a day is a challenge. For others, taking 4-6 extra tablets isn’t a economically viable option.

Second + Third Trimester Considerations


· Lactobacillus rhamnosus (LGG) when taken in 🤰 LGG has a substantial body of evidence confirming efficacy at a dose of 20 billion per day in the last trimester and throughout breastfeeding, or 10 billion when given direct to infants.

· In a 2015 randomised trial, 159 mother-baby pairs were given 10 billion LGG daily prenatally and until the age of six months. At the age of 13 years, no children in the LGG group had developed behavioural complaints, compared to 17% of the control group. 3


· Many people aren’t meeting the recommended 440mg of choline per day. There is recent evidence suggesting 960mg of choline per day may be more optimal.4

· Pregnancy and lactation are times when demand for choline is especially high, whereby transport of choline from mother to foetus depletes maternal plasma choline. This nutrient is needed for brain development, acetylcholine production and placental growth. Choline is required in large amounts in the third trimester when foetal organ growth is extremely rapid. Research has shown that pregnant women do not consume sufficient amounts of choline, levels which have found to be significantly higher in serum concentrations in pregnant women, compared to adults, and are six to seven times higher in the foetus and newborn. Choline also shows synergistic benefits when combined with DHA during pregnancy, enhancing neurodevelopment of foetal hippocampus compared to choline or DHA alone. 5

DHA (aka fish or algae oil)

· Foetal brain accumulates approximately ~60mg/kg per day in the last trimester of pregnancy of DHA. 6

· Supplementation ensures adequate maternal levels to pass onto the foetus.


· The calcium requirement in pregnancy doesn’t actually change from non-pregnant. I find many of my pregnancy ladies aren’t getting adequate calcium. Why is it so important in pregnancy? Because the foetus needs it for the development of their skeleton but also low calcium intake is correlated with preeclampsia.

· If mum isn’t consuming adequate calcium though the diet, she starts to dip into her bone stores of calcium. This can mobilise lead, 7 which mum has accumulated over her lifetime. Lead is a neurotoxin. Not something you want to exposure your baby to.

· If I can’t simply optimise mums’ diet, I will supplement with approximately half the RDI of calcium. 8


· Many women I see are iron deficient by the time they reach their second trimester. Iron deficient in pregnancy can cause fatigue due to reduce oxygen carrying in the blood cells. Uncorrected iron deficiency anaemia can lead to reduced birth weight, preterm delivery and there is an increase instance of autism. 9

· Iron supplements should always be taken away from calcium and vice versa.

· Always check with your doctor that you are actually iron deficient or anaemic before supplementing as iron can be toxic and inflammatory if not required.

Vitamin D

· Having my clinic in Australia, you would think I wouldn’t see vitamin D deficiency, but I do.

· Optimal vitamin D status (50nmol/L -150nmol/L) has been shown to reduce the risk for gestations diabetes, preeclampsia, preterm birth and low birth weight.

· Pregnant women should have their vitamin D level monitored, at least once in pregnancy and hopeful before conception. Especially, if it is a winter pregnancy.

· Most prenatal multivitamins contain at least 400iu daily, but this may be insufficient if you have pre-existing low levels. Women with levels <50nmol/L should speak to there healthcare practitioner about appropriate and safe dosing. Vitamin D is a fat soluble vitamin so can be toxic (and immunosuppressive) in large dosages. 8

Vitamin K

· Towards the last weeks of pregnancy, I sometimes supplement my clients with vitamin K.

· Vitamin K is essential for the formation of blood clotting factors. Something you are going to need after either a vaginal or c-section delivery!

· Vitamin K can be synthesised by gut bacteria and is found in green leafy vegetables.

· Whether you need vitamin K supplementation depends on three things, how much vitamin K you are getting in your diet, if you have malabsorption or existing medical conditions like epilepsy. 10

If you are unsure about what supplements you require during pregnancy, please reach out here. Supplementation in pregnancy is very individual and depends on a range of factors including dietary intake, risk factors and lifestyle.

My ebook "A Holistic Guide to Preconception + Pregnancy" is also available for instant download here. It is packed full of nutritional information to support both fertility and a health pregnancy.


1. Obeid, R., Holzgreve, W. & Pietrzik, K. Is 5-methyltetrahydrofolate an alternative to folic acid for the prevention of neural tube defects? J. Perinat. Med. 41, (2013).

2. Zhou, S. J. et al. Association Between Maternal Iodine Intake in Pregnancy and Childhood Neurodevelopment at Age 18 Months. Am. J. Epidemiol. 188, 332–338 (2019).

3. Ho, M. et al. Oral Lactobacillus rhamnosus GR-1 and Lactobacillus reuteri RC-14 to reduce Group B Streptococcus colonization in pregnant women: A randomized controlled trial. Taiwan. J. Obstet. Gynecol. 55, 515–518 (2016).

4. Korsmo, H. W., Jiang, X. & Caudill, M. A. Choline: Exploring the Growing Science on Its Benefits for Moms and Babies. Nutrients 11, 1823 (2019).

5. Boeke, C. E. et al. Choline Intake During Pregnancy and Child Cognition at Age 7 Years. Am. J. Epidemiol. 177, 1338–1347 (2013).

6. Lauritzen, L. et al. DHA Effects in Brain Development and Function. Nutrients 8, 6 (2016).

7. Riess, M. L. & Halm, J. K. Lead Poisoning in an Adult: Lead Mobilization by Pregnancy? J. Gen. Intern. Med. 22, 1212–1215 (2007).

8. pregnancy-care-guidelines.pdf.

9. Schmidt, R. J., Tancredi, D. J., Krakowiak, P., Hansen, R. L. & Ozonoff, S. Maternal Intake of Supplemental Iron and Risk of Autism Spectrum Disorder. Am. J. Epidemiol. 180, 890–900 (2014).

10. Shahrook, S., Ota, E., Hanada, N., Sawada, K. & Mori, R. Vitamin K supplementation during pregnancy for improving outcomes: a systematic review and meta-analysis. Sci. Rep. 8, 11459 (2018).


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