Vitamin K: The reasons and results
(Editor’s note: the following are excerpts from a lengthy article published in Midwifery Today magazine. For fuller understanding of the complex topic, we recommend you read the article, which lists 40 references, in its entirety. This issue also contains two other excellent, referenced articles about vitamin K. Article by Jennifer Enock, “Babies and vitamin K”, Midwifery Today Issue 56 www.midwiferytoday.com, Winter 2000)
The recommended daily intake (RDI) of vitamin K is 10 mcg for infants. Human milk does not provide this much vitamin K to the breastfed baby at any stage of lactation, despite the fact that mothers on average consumed 670% of the adult RDI, In fact, nursing babies received on average only 7 – 13% of the RDI. Giving the mothers a modest daily supplement of 88 mcg/ day did not increase breast milk concentration of the vitamin. A large daily supplement, 5000 mcg, taken by breastfeeding mothers increased the amount of vitamin K in their milk to the same level with which formulas are fortified.
Whether or not the RDI represents the amount of vitamin K that babies truly need is a matter that can be debated. The small qualities of vitamin K in human milk are adequate for most babies, as evidenced by the fact that vast majority of breast fed babies do not develop vitamin K deficiency bleeding (VKDB).
A single IM dose results in extremely high levels of vitamin K in the newborns’ blood soon after injection: the peak median plasma concentration at 12 hours is 9000 times the normal adult level, and from one to four days after the injection the level are about 100 times higher than in a normal adult. It is unknown what risk there is in exposing the newborn to these high concentrations of vitamin K. Cancer was suggested as a potential risk as early as 1983, but the evidence to date is inconclusive.
Golding et. al. found that intramuscular vitamin K supplementation given to newborns was associated with an increased risk of certain childhood cancers ( B J Cancer 62: 304-308) This unexpected result occurred in a national cohort study done in Britain. The authors found similar results in a second study. Several subsequent studies showed no evidence of risk. However, the most recent studies have been unable to excludes the possibility that intramuscular vitamin K given to newborns may raise their risk for developing acute lymphoblastic leukemia in childhood. The evidence does not prove that intramuscular vitamin K is carcinogenic, and the risk, is any, is likely to be low. The evidence does not suggest that oral vitamin K poses a risk.
Intramuscular vitamin K prevents late VKDB in almost all babies. Although late VKDB does sometimes occur after a single oral dose, and to a lesser extent after a series of three doses, these oral dosing regimens do confer some degree of protection.
A recent study, using data from Britain, estimates that among breastfed babies not given vitamin K, the risk of late VKDB is 19.1 per 100,000, or almost one in 5,000. This risk can be considered low because the vast majority of babies will not develop the disease. A midwife could practice for many years and never see a single case.
Recommendations:
Do research during pregnancy so you can make an informed decision about whether of not you want vitamin K prophylaxis and if so, which type, IM or oral.
Your baby’s health care provider should be made aware of whether or not the baby received vitamin K, and if so, in what form. Knowing the baby did not receive prophylaxis can improve the chances of early diagnosis and treatment in the rare event of VKDB.
For parents who decide not to give vitamin K, give a hondout explaining the symptoms of VKDB and advise them to obtain immediate care for a baby who develops symptoms.
If jaundice is present after two weeks, bilirubin should be evaluated to see which type of jaundice is present. Conjugated hyperbilirubinemia may indicate cholestasis, which puts a baby at higher risk of developing VKDB.
We suggest that it is extremely unlikely that the relationship between vitamin K levels and hemorrhagic disesase of the newborn (HDN) is a simple one. I can think of several birth-related factors that might affect this issue. For instance, we should ask a woman what happened during the third stage of her labor. Was the cord cut quickly, or was the baby allowed as much time as she needed to regulate the amount of clotting factors and other relevant components in the baby’s blood? What impact does the woman’s diet during pregnancy on the situation? And what are the possible reasons that nature intended babies to have low levels of vitamin K?
I worked in a community midwifery practice at a time when the decision was made to increase from one to three doses of the (oral) vitamin K given to breastfed babies. The first dose was given at birth and the second on the seventh day postpartum. While we would generally stop seeing women on the tenth day postpartum, the other midwives and I noticed that almost as soon as this new policy become practice, we suddenly had moderate numbers of women who were not discharged from midwifery care until the twelfth or thirteenth day. Analysis of the records showed that the majority of these women had babies who were becoming jaundiced on the eighth or nineth day following their second dose of vitamin K. Another midwife had suggested that perhaps babies cannot handle the increased prothrombin that comes about as a result of receiving vitamin K. Perhaps this would explain why babies are born with their relatively low levels.
Von Kries (BMJ 316: 161-62) summarizes some of the recent history of vitamin K, which in some areas was not given until the early 1980’s because late-onset HDN had not been a problem until then. This in itself should raise concerns. If all babies were pathologically deficient in vitamin K, surely someone would have noticed in these areas sometime before 1980’s. How does the increase (in some areas) of late onset HDN relate to the changes in the practices women experience during childbirth? Did the “need” for routine vitamin K increase alongside increasing medicalization of birth?
Sara Wickham, “Vitamin K: A Flaw in the Blueprint?” Midwifery Today Issue 56