Ghada Metwally ELGohary
Professor Of Internal Medicine /Adult Hematology And SCT
Ain Shams University
Faculty Of Medicine, Cairo,Egypt
Bassim Albeirouti
Consultant of Adult Hematology & TCT
KFSHRC Jeddah
Vitamin B12 and Anemia
Vitamin B12 (cobalamin) is essential for DNA synthesis, cell division, and neurological function – all critical processes in reproduction and pregnancy
Megaloblastic Anemia: Vitamin B12 (and folate) are required for proper red blood cell (RBC) formation. B12 deficiency leads to megaloblastic anemia – characterized by large, immature RBCs and a drop in healthy RBC count.
A lady with Vitamin B 12 deficiency is presented with anemic Symptoms include fatigue, weakness, shortness of breath, and pallor. B12 deficiency can also cause menstrual irregularities and contribute to infertility. The WHO notes that, besides iron deficiency, deficiencies of vitamin B12 and folate are significantly increasing. Thus, a young woman with unexplained anemia (especially macrocytic anemia) should be evaluated for B12 deficiency, particularly if she’s attempting to conceive or becomes pregnant, because anemia can reduce fertility and increase multiple risks in pregnancy.
Importance of Vitamin B12 in Reproductive Function
Adequate Vitamin B12 level helps to maintain ovarian health and ovum quality; conversely, deficiency has been linked to infertility, ovulatory dysfunction, and even recurrent miscarriage. Over half of women with infertility have suboptimal B12 levels. NHS guidance explicitly states that Vitamin B12 deficiency can sometimes cause temporary infertility (inability to conceive) which usually reverses with proper B12 treatment.
Women with Polycystic Ovary Syndrome (PCOS) often take metformin to improve insulin resistance and induce ovulation. Metformin, however, can impair B12 absorption and lead to deficiency. Clinical guidelines (e.g. NICE) advise monitoring B12 levels in patients on long-term metformin, including many PCOS patients.
In pregnancy, untreated B12 deficiency anemia can lead to low birth weight and developmental problems in the baby. The NHS states that B 12 deficiency is also associated with a higher risk of neural tube defects (NTDs) in the fetus like spina bifida if the mother is deficient during early pregnancy (Folate is the primary nutrient for NTD prevention, but B12 is a co-factor in folate metabolism; low maternal B12 is independently linked to NTD risk in some research. Because of these concerns, obstetric guidelines advise ensuring pregnant women have adequate B12.
Endometriosis: There is no direct evidence that vitamin B12 “treats” endometriosis, but chronic conditions like endometriosis can coincide with nutritional deficits. Dietary restrictions or co-existing gut issues (e.g. from surgery or concurrent conditions like celiac disease) may lead to malabsorption of B12. Indeed, nutritional studies in women with chronic pelvic pain conditions have documented deficiencies in iron, folate, vitamin D and B12. Correcting any B12 deficiency in these patients could support better Ovulation quality and implantation, although the primary treatments for endometriosis remain surgical and hormonal.
Once B12 deficiency anemia is diagnosed, standard treatment involves replenishing B12 stores (often via injections initially). Hematologic response is usually brisk – within weeks, the bone marrow starts producing normal RBCs. Guidelines (e.g., ACOG Practice Bulletins on anemia in pregnancy) note that oral folic acid (1 mg daily) will treat folate-deficiency anemia , but if anemia persists, B12 must be assessed. An important clinical point is to avoid giving high-dose folic acid alone in someone with B12 deficiency, as folate can mask the anemia while neurological damage from B12 deficiency progresses. Therefore, doctors typically supplement both folic acid and B12 in a macrocytic anemia until labs confirm which deficiency is present. By correcting anemia due to B12 deficiency, women often see improvement in energy and fertility. In fact, one complication of untreated B12 deficiency is heart failure due to severe anemia, and treating the deficiency mitigates that risk. Overall, maintaining normal B12 levels is part of good preconception care to ensure women enter pregnancy without anemia or related complication.
In practice, this means healthcare providers should screen for Vitamin B12 issues in at-risk women (those with anemia, strict diets, malabsorption conditions, or on long-term metformin) and treat deficiencies according to established protocols. Treatment can be tailored – injectable, intramuscular (IM) vs. oral B12 – based on clinical context, ensuring effective resolution of the deficiency. Combined folic acid and B12 supplementation is often the strategy in preconception care to cover all bases for preventing neural tube defects and improving fertility success.
In pregnancy, the Specialist Pharmacy Service in the UK explicitly states both IM hydroxocobalamin and oral cyanocobalamin are options for treating B12 deficiency, and the choice can depend on severity and clinical context. Notably, if there is neurological involvement (e.g. neuropathy, cognitive impairment), guidelines urge using IM B12 for more rapid and assured replenishment. Once the deficiency is corrected and if the cause is lifelong (like pernicious anemia), maintenance can be either periodic injections or daily high-dose oral B12.
With oral therapy, monitoring is important. NICE suggests rechecking B12 status after around 3 months of oral treatment to confirm absorption is adequate. If the oral route fails to raise levels or if symptoms persist, switching to injections is indicated. Some patients might start with injections to refill B12 stores quickly, and the new NICE guideline does acknowledge patient preference in deciding the route.
The Pernicious Anaemia Society and patient groups have advocated for greater use of oral B12 for those who don’t tolerate frequent injection. The NIH Office of Dietary Supplements notes that high-dose oral B12 appears as effective as IM for many people, citing evidence that oral and intramuscular routes produced similar outcomes in correcting deficiency.
All these points illustrate why international guidelines stress the importance of recognizing and correcting B12 deficiency in women. From the WHO’s global nutrition recommendations, to ACOG’s prenatal nutritional advice, to NICE’s detailed management pathway, the message is uniform: maintain adequate B12 levels for optimal Female health outcomes.
Conclusion:
The clinicians can significantly improve the fertility and increase the pregnancy score for many ladies and make their dream comes true, simply by proper Vitamin replacement and proper Adjustment in vitamin B12 and folic acid levels
Sources:
Vitamin B12 clinical insights and guidelines (WHO, ACOG, NICE).
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