Vitamin K injections for newborns are being omitted more frequently in Sweden, according to a nationwide study that found a higher risk of bleeding among children who did not receive the routine treatment. The proportion remained low but more than doubled between 2006 and 2021.
The study published in JAMA Pediatrics examined more than two million children born in Sweden between 2003 and 2021. It found that 1.50 percent of newborns had no recorded intramuscular vitamin K injection in 2021, compared with 0.66 percent in 2006.
In numerical terms, the total rose from 667 newborns in 2006 to 1,619 in 2021.
Why newborn vitamin K injections are given
Newborn children have naturally low levels of vitamin K, which the body needs to activate proteins involved in blood clotting. The vitamin passes only in limited quantities through the placenta, is present at low concentrations in breast milk and cannot initially be produced sufficiently by an infant’s gut bacteria.
This temporary deficiency can lead to vitamin K deficiency bleeding, a rare condition that can cause internal or intracranial haemorrhages and may be life-threatening.
Sweden introduced intramuscular vitamin K prophylaxis nationwide in 1961. An oral regimen introduced in 1986 was followed by the return of deficiency-related bleeding, and the country resumed routine injections in 1989. Newborns are now normally offered a single injection in the thigh shortly after birth.
Bleeding risk was higher without the injection
Researchers identified 2,020,302 eligible births, of which 24,089 had no record of an intramuscular vitamin K injection.
Children without a recorded injection had around 52 percent higher adjusted odds of receiving a bleeding diagnosis during their first six months. Their adjusted odds of bleeding in or around the brain were almost three times higher than among children who received the injection.
The research establishes an association rather than proving that the absence of the injection caused every recorded bleeding episode. The authors used diagnoses from Swedish health registers and included all non-traumatic bleeding, not only clinically confirmed cases of vitamin K deficiency bleeding.
Documentation errors may also account for some missing records. The researchers excluded data from Värmland in 2021 after more than 80 percent of records lacked documentation, a level considered unlikely to represent actual non-administration.
Researchers cannot directly identify parents’ reasons
The registers did not record why the injections were omitted. Parental refusal is considered the most likely explanation in most cases because medical contraindications are rare, but the study could not directly establish individual parents’ decisions.
According to Sweden Herald, researcher Eleni Simatou, a doctoral student at Karolinska Institutet and paediatric neurologist at Astrid Lindgren Children’s Hospital, said parents may fear pain or side effects, believe dietary changes during pregnancy are sufficient, or distrust healthcare interventions more broadly.
“We find this worrying, especially because we know that vitamin K can protect children from bleeding related to vitamin K deficiency,” Simatou said.
Previous international research has also linked refusal of newborn vitamin K with later rejection of childhood vaccinations, although the Swedish study did not examine vaccination decisions.
Oral vitamin K offered as an alternative
When an injection cannot be given, Swedish healthcare services may offer vitamin K orally. The regimen requires an initial dose after birth followed by one dose every week for 12 weeks.
About ten percent of the children without an intramuscular injection received at least one oral dose. This group also showed a higher bleeding risk than children given the injection, although the researchers warned that the number of oral cases was limited and that the registers could not establish whether families completed the full course.
Missed doses and conditions affecting absorption can make oral prophylaxis less reliable than a single injection.
The authors concluded that Swedish healthcare professionals should continue explaining the purpose of vitamin K prophylaxis during prenatal care and after birth. Although the proportion of newborns missing the injection remains small, its gradual increase could expose more children to a preventable risk during their first months of life.
