Bloodwork Timeline for a Proactive Pregnancy

Following on from my last article “Postpartum begins in the Preconception Phase”, my focus continues to be discussing the  importance of planning ahead and taking a proactive approach, and this applies to pregnancy as much as it does to postpartum.

Depending on your care provider and the setting you choose, the conventional standard of care generally requires blood work in all three trimesters, and may ask for extra monitoring (especially for iron which we’ll cover shortly) if they feel it’s necessary. Some of the standard run of the mill tests include blood type testing, Rubella, Hepatitis B & C and iron studies (again – more on this soon).

At The Natural Nutritionist we definitely take a proactive approach and ideally want to see your bloodwork in the preconception phase so we can support you as much as necessary before you embark on your active conception journey.

Here is some information regarding the blood tests we like to see as you move along from preconception right through to postpartum:

Bloodwork Timeline:

Preconception: (ideally at least 12 weeks prior to active conception) FBE, iron studies, HS C-reactive protein, BGL, HbA1c, folate, homocysteine, active B12, total B12, MTHFR, TSH, FT3, FT4, Tg Ab, TPO Ab, fasting insulin, red cell magnesium, zinc, copper, urine: iodine.

Trimester 1: (especially if preconception bloods were not completed. If they were you can remove , FT3,Tg Ab, TPO Ab, FT4, serum zinc, copper and MTHFR – unless any of them required improvements and a need to retest): FBE, Iron studies, Hb, folate, homocysteine, active B12, total B12, vitamin D, TSH, FT3,Tg Ab, TPO Ab, FT4, BGL, HbA1c, fasting insulin, C-reactive protein, liver function, serum zinc, copper.

Week 20: FBE, Iron studies, TSH, FT3, FT4, active B12.

Week 27: FBE, Iron studies, TSH, FT3, FT4, fructosamine, at-home glucose monitoring.

Week 35: FBE, Iron Studies.

Postpartum: (6 weeks +) CBC/FBC, electrolytes (EUC/BUN) including corrected calcium and LFT, iron studies, hs-CRP, active B12, thyroid including FT3, FT4, TSH, and thyroid antibodies, folate, 25-OH vitamin D, plasma zinc, serum copper, ceruloplasmin, homocysteine, whole blood histamine, urine: iodine.

It starts off in detail so we can cover all bases and set our clients up for pregnancy success. As you move through your pregnancy it becomes much more simplified and the main areas we want to continue to monitor are mostly centered around iron status and thyroid health. After the baby comes and the postpartum dust has started to settle we request another round of comprehensive bloods, similar to the preconception phase so we can provide a tailored approach to your postpartum replenishment journey.

Now let’s discuss a few markers, their importance, why there is sometimes some confusion, and why being proactive can make a big difference.


Steph has written a great article explaining the basics of this and how it can relate to fertility. Please read it here. In summary, an MTHFR gene mutation creates a defective MTHFR enzyme, which is critical for the role of methylation in the body. When the mutation is present it can contribute to elevated homocysteine (inflammation) levels, and an inability to convert folic acid to its active form. This can lead to dangerously high levels of folic acid in the red blood cells (hence why you will never hear us recommend Elevit at TNN). Left undetected, it can be a common reason for miscarriage. Being aware of someone’s MTHFR status in conjunction with their homocysteine and B12 levels is a really helpful way to supplement them and provide tailored nutrition advice. It’s a very common mutation and the key is to be aware of it and prescribe accordingly. Ensuring that your prenatal includes methylfolate or folinic acid is a great place to start.

HbA1c and Fructosamine

HbA1c is basically an average of your blood glucose levels over a three month period. It is a great predictor of gestational diabetes risk, especially when conducted in the first trimester. Fructosamine is a test that measures how glycated protein is in the blood or how many sugar molecules are circulating. It is another great indicator or predictor of gestational diabetes. At TNN we are definitely more inclined to give our clients alternative options to the oral glucose tolerance test (OGTT) which involves drinking 75- 100g of glucose, and these blood tests as well as some at-home glucose monitoring kits are a great way to test for gestational diabetes and put any nutrition, supporting supplementation and stress management practices into place if necessary. Read more here and here.

Thyroid Panel

Thyroid Stimulating Hormone is a pituitary hormone that signals the thyroid gland to make T4. We like to monitor it over the trimesters because it has an interesting relationship with iodine, in that excess iodine can actually suppress TSH, setting the scene for thyroid issues in the future. Postpartum is a critical time for managing thyroid health so being aware of this one can also help pave the way for a successful postpartum journey. It’s also very important to note that a TSH reading  >2.5 can double your miscarriage risk, which quadruples when combined with any elevation in thyroid antibodies. At TNN we also find it helpful to test FT3 and FT4 in each trimester, and interpret the results accordingly. For example, maternal transfer of T4 to a growing baby and an increased conversion of T3 is normal as the trimesters progress so we would expect to see T4 decline, while T3 increases. 

Iron Studies

Iron status is one that seems to come up all the time with our pregnant clients. There needs to be more understanding of what happens with our iron as we progress through our pregnancy, why being proactive matters and why ferritin is not enough to measure true iron status. A few key points worth noting:

  • Conventional ranges for iron and other associated markers DO NOT change for pregnancy which can be confusing.
  • Haemodilution (increased blood volume) naturally occurs during pregnancy which causes a normal amount of maternal iron and related markers like ferritin and haemoglobin to be impacted. 
  • Ferritin and serum iron are not the most accurate indicators of true iron status and should be considered in conjunction with transferrin, transferrin saturation, hemoglobin and platelets.
  • Someone’s starting point is very important e.g. if you had lower (but still within optimal ranges) haemoglobin and platelets to begin with, they are going to get lower and where they started should be considered when assessing risk.
  • Taking a proactive approach in the early stages that includes supporting nutrients for optimal iron like vitamin A (hello offal), magnesium, vitamin C and copper is key to optimising levels as much as possible.

Hopefully this article has highlighted the thorough and proactive approach that we take at TNN with our preconception and beyond clients. Applied knowledge is power and the more we know about a person’s unique status, the more accurately we can support them.

If you are keen to find out more, please reach out. We love hearing from you!


Twig G, Shina A, Amital H, Shoenfeld Y. Pathogenesis of infertility and recurrent pregnancy loss in thyroid autoimmunity. J Autoimmun. 2012;38(2-3):J275-J281. doi:10.1016/j.jaut.2011.11.014

D’Ippolito S, Ticconi C, Tersigni C, et al. The pathogenic role of autoantibodies in recurrent pregnancy loss. Am J Reprod Immunol. 2020;83(1):e13200. doi:10.1111/aji.13200

Sarkar D. Recurrent pregnancy loss in patients with thyroid dysfunction. Indian J Endocrinol Metab. 2012;16(Suppl 2):S350-S351. doi:10.4103/2230-8210.104088

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