FatCamera/GettyBabies aren’t born with enough vitamin K, which is essential to clot blood. This is why it’s recommended in Australia that all newborns receive a vitamin K injection at birth.Without it, they’re at risk of vitamin K deficiency bleeding, a rare but life-threatening condition. However, two large studies from the United States and Sweden have found a rising proportion of newborns with no record of receiving the shot. Neither study recorded why.Australia has no comparable national data, and a surveillance project that monitored vitamin K deficiency bleeding in infants ended in 2017.Two states do keep count, though, and both show a decline. Queensland Health figures obtained by the ABC show 98.3% of babies received vitamin K in 2016, falling to 95.5% by 2025 – meaning more than 2,500 babies went without last year alone.Tasmania’s rate fell from 99% to 97% over the same period. No other state or territory publishes the figures.What is the vitamin K injection?First, it’s not a vaccine, it’s a vitamin preparation.Newborns have low stores of vitamin K because very little crosses the placenta during pregnancy. In newborns, the gut bacteria that produce vitamin K are not yet well-established. Levels in human milk are also low.For healthy newborns, Australia’s guidelines recommend a one milligram injection at birth – usually in the thigh muscle.There is also an oral option. This has three 2mg doses: at birth, at 3–5 days, and in the fourth week after birth. The final dose is not required for babies who mainly drink formula, as it contains vitamin K.However, the injection is the preferred option because it is more reliable and requires only one dose. As with other injections, it can cause brief pain and occasionally some redness, swelling or bruising at the injection site. Serious reactions are very rare.What can happen without it?Babies can develop vitamin K deficiency bleeding in the first week of life, but the most dangerous form appears later, from eight days to six months old, typically at 1–3 months.This condition is rare. Across 25 years of Australian surveillance, there were 0.84 reported new cases for every 100,000 live births, roughly two or three reported cases a year. However, this number could be higher, as the data relies on voluntary reporting.In 30–50% of cases that develop after the first week, the bleeding is inside the skull, which can be life-threatening.Underlying liver disease, which can impair babies’ absorption of vitamin K, was confirmed in 43% of the late Australian cases.What we know about past casesA 2019 surveillance study looked at how many vitamin K deficiency bleeding cases Australian paediatricians reported between 1993 and 2017.During this period, there were 58 cases. Among these, 33 babies had received no vitamin K at birth – in 28 cases because their parents had declined it. In the other five cases the reason wasn’t recorded or there was no clinician present.Of the 58 babies, six died, all from bleeding inside the skull. Three of those deaths followed a home birth where vitamin K had been refused.Parents declined at 11 of the 13 home births in the study, and 11 of the 28 refusals were in northern New South Wales and Southeast Queensland.It’s important to note this study counted only reported cases of vitamin K deficiency bleeding, not vitamin K injections and refusals across all births.But among affected babies, there was a clear increase in parental refusal. In 1993–2005, 32% of cases involved parents refusing the injection. In 2006–17, the proportion rose to 63%.Injection rates are falling overseasA 2025 US study looked at the electronic health records of more than 5 million newborns across 403 hospitals. It found the proportion with no record of a vitamin K injection rose from 2.92% in 2017 to 5.18% in 2024.The study measured cases where the newborn did not receive the injection, not confirmed refusal: parents’ or clinicians’ reasons were not recorded. But unlike Australia, there is no approved oral vitamin K for newborns in the US, so babies without a recorded injection were unlikely to have had drops instead. In Sweden, a recent study looked at more than 2 million newborns between 2003 and 2021. The proportion of cases where the newborn didn’t receive a vitamin K injection actually fell between 2003 (1.32%) and 2006 (0.66%), but then more than doubled to 1.5% in 2021.Why do some parents decline it?There is no published Australian research on why parents decline.International evidence suggests there’s no single reason. US research has identified concerns about perceived injection risks, ingredients, dose and side effects; a preference for a more “natural” approach; mistrust of medical or pharmaceutical advice; and information encountered online or through social networks.In 2015, a New Zealand study found parents who declined newborn vitamin K were more likely to decline later childhood immunisation.One enduring concern followed a 1992 study reporting a link between the then-used formulation and childhood cancer. Better-quality studies did not confirm the finding. This older formulation is no longer used in Australia.If you’re expecting a babyGiving birth can be a difficult time to weigh up new medical information. So it’s a good idea to think about the vitamin K injection ahead of time.Ask your midwife, doctor or obstetrician for more information during pregnancy about what the injection involves, and make the decision before the birth. If you choose the oral version, remember it’s three doses, not one. It’s that final dose that protects against the late bleeding that can cause brain haemorrhage.The authors do not work for, consult, own shares in or receive funding from any company or organisation that would benefit from this article, and have disclosed no relevant affiliations beyond their academic appointment.