Ask about prenatal nutrition and the list is well rehearsed and it majorly includes folic acid, iron, DHA, choline and vitamin D. Vitamin K2 almost never comes up, in conversation or on most prenatal labels. That’s a gap worth noticing, because a study published in 2025 measured vitamin K2 directly in pregnant women for the first time in this context and found deficiency far more common than the silence around it would suggest.
The Study That Measured It Directly
Researchers at a Beijing maternity hospital drew blood from 197 pregnant women one to two days before delivery, then tested umbilical cord blood from their newborns at birth (Liu et al., 2025). Using the deficiency cutoff of below 0.1 ng/mL, 38.6% of the mothers tested vitamin K2-deficient in late pregnancy. In that deficient group, both maternal and newborn osteocalcin, a bone protein that depends on vitamin K to function, came back significantly higher (a sign it wasn’t being properly activated), along with newborn parathyroid hormone. Maternal vitamin K2 levels also correlated significantly with the newborn’s vitamin D status, and both maternal K2 and newborn calcium levels independently predicted whether a newborn’s vitamin D came back insufficient. The authors called it the first study to link maternal K2 levels directly to newborn bone chemistry.
Why the Placenta Doesn’t Solve This on Its Own
Babies can’t simply draw on their mother’s vitamin K reserves. Transport of vitamin K across the placenta is poor, which is a well-documented contributor to newborns starting life with very low vitamin K stores of their own (Office of Dietary Supplements, National Institutes of Health, 2021). That’s the reason nearly every newborn in a hospital birth receives a vitamin K injection shortly after delivery typically vitamin K1, given directly to the baby, precisely because so little of the mother’s supply reaches the baby on its own. A mother’s K2 status doesn’t automatically become her baby’s K2 status; the transfer is limited by design.
What Supplementation Trials Have (and Haven’t) Shown
A 2018 systematic review pooling six older trials and more than 21,000 mother-newborn pairs found that vitamin K supplementation during pregnancy reliably raised maternal plasma vitamin K1 levels (Shahrook et al., 2018). What it didn’t find was a statistically significant reduction in neonatal bleeding from supplementation alone, and the certainty of that evidence was rated very low, with several relevant outcomes never measured at all. Read plainly, that’s not a null result so much as an evidence gap as the trials show supplementation changes maternal vitamin K status, but haven’t been designed well enough yet to say what that changes for the baby beyond what’s already being addressed by the standard newborn injection.
Why Form Matters As Well
As with other applications of vitamin K2, the specific form affects how long it stays useful in circulation. A bioavailability study found that after a single dose, MK-7 stayed detectable in serum for up to 48 hours, while MK-4 at the same dose wasn’t detectable at any point measured (Sato et al., 2012). Pregnancy is a nine-month state, not a single event, which is part of why MK-7 shows up more often than MK-4 in the newer research on maternal vitamin K status.
Where TerraQuino Fits In
TerraQuino produces MK-7 through a controlled fermentation process, delivering the long-chain, allergen-free vitamin K2-7 associated with the sustained blood levels documented above.
It’s formulated for tablets, capsules, softgels, sachets, and liquids, and pairs cleanly with vitamin D3, calcium, and other nutrients already standard in prenatal formulations.
TerraQuino doesn’t make pregnancy-specific therapeutic claims for its ingredient as the clinical case is still developing but it gives formulators a bioavailability-tested K2 source to build toward that research as it matures.
FAQs
Is vitamin K2 deficiency actually common during pregnancy?
In the one study that measured it directly, yes — 38.6% of the 197 women tested were deficient in late pregnancy (Liu et al., 2025). It’s a single study from one hospital population, so it’s a strong signal rather than a settled national statistic.
If I take vitamin K2, does my baby still need the vitamin K shot at birth?
Yes. The newborn injection is typically vitamin K1, given directly to the baby because so little vitamin K crosses the placenta regardless of the mother’s own status (Office of Dietary Supplements, National Institutes of Health, 2021). Maternal K2 intake and the newborn injection address different parts of the same gap, not the same one.
Should I start taking a vitamin K2 supplement during pregnancy?
That’s a conversation for your OB or midwife, not a call to make from a blog post. The research here is real but still early, and pregnancy supplementation decisions should account for your individual health history and current prenatal regimen.
Is vitamin K2 the same as the vitamin K my doctor might mention?
No. Vitamin K1 (phylloquinone) is the form used in the newborn injection and most older pregnancy research; vitamin K2 (including MK-7) is a related but distinct form studied more in the newer maternal bone-metabolism research described above (Liu et al., 2025).
References
Liu, X., Wang, S., Chen, H., Qian, N., Wu, L., Liu, Y., Hou, Z., Bai, Y., & Jiang, H. (2025). Association between maternal vitamin K2 levels in late pregnancy and newborn bone metabolism. Food Science & Nutrition, 13(6), Article e70363. https://doi.org/10.1002/fsn3.70363
Office of Dietary Supplements, National Institutes of Health. (2021, March 29). Vitamin K: Fact sheet for health professionals. U.S. Department of Health and Human Services. https://ods.od.nih.gov/factsheets/VitaminK-HealthProfessional/
Sato, T., Schurgers, L. J., & Uenishi, K. (2012). Comparison of menaquinone-4 and menaquinone-7 bioavailability in healthy women. Nutrition Journal, 11, Article 93. https://doi.org/10.1186/1475-2891-11-93
Shahrook, S., Ota, E., Hanada, N., Sawada, K., & Mori, R. (2018). Vitamin K supplementation during pregnancy for improving outcomes: A systematic review and meta-analysis. Scientific Reports, 8, Article 11459. https://doi.org/10.1038/s41598-018-29616-y
