Parents of newborn girls are more likely to refuse lifesaving vitamin K and hepatitis B vaccine shot, researchers find

by Sanjukta Mondal, Medical Xpress

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edited by Sadie Harley, reviewed by Robert Egan

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A simple shot given shortly after birth can protect babies from a rare but potentially life-threatening condition known as vitamin K deficiency bleeding (VKDB). When newborns don't have enough vitamin K, their blood can't clot effectively, putting them at risk of severe internal bleeding in the intestines or the brain, which can cause organ damage or even prove fatal.

A recent study has uncovered a concerning pattern: parents of female newborns are twice as likely to decline vitamin K prophylaxis as parents of male newborns. After observing more than 93,000 newborns, researchers found that for every 1,000 babies born, about eight missed the vitamin K shot, while nearly 101 went without the hepatitis B vaccine.

One possible reason for the gender gap comes down to circumcision. Since vitamin K is essential for blood clotting, many hospitals refuse to perform a circumcision unless a baby boy has first received the vitamin K shot. Unlike boys, girls do not undergo circumcision. Parents who are hesitant about the vitamin K shot face less pressure to accept it, which may contribute to the higher refusal rates among daughters. The findings are published in JAMA Network Open.

Sex disparity in parental decline

Hepatitis B is a highly contagious virus that targets the liver and remains the world's leading cause of liver cancer. For infants, the stakes are particularly high because, without vaccination, as many as 90% of babies infected in their first year of life will develop a chronic infection, putting them at risk of liver failure, liver cancer and premature death.

Similarly, skipping the vitamin K shot at birth leaves infants vulnerable to VKDB for the first six months of their lives, a condition that can cause lasting damage and in some cases prove fatal.

Despite how crucial these shots are, studies are finding an alarming rise in parents refusing this prophylactic care for infants. To investigate this trend, researchers conducted a retrospective study, reviewing past medical records to examine the decisions parents made regarding their babies' preventive care and the factors that may have influenced those choices.

They analyzed the records of 93,163 newborns born between January 2018 and December 2025, including only babies born at 35 weeks or later who were healthy enough for regular nursery care.

They found that more parents are saying no to these newborn treatments, but not all babies are affected equally. Girls were twice as likely as boys to miss the vitamin K shot, and nearly two-thirds of babies who did not receive it were female. The same pattern showed up with the hepatitis B vaccine, although the gap between girls and boys was smaller.

Another trend that stood out was that parents who said no to one treatment often said no to the other, with 83% of babies who missed the vitamin K shot also going without the hepatitis B vaccine. These results also highlight how cultural practices like circumcision can influence more than the procedure itself: It shields boys from the effects of parental hesitancy, leaving girls more likely to miss out on preventive care.

The data also revealed that a family's background shaped these decisions in telling ways. Parents with private insurance and those who identified as Asian, Hispanic or Latina were more likely to accept the treatments, whereas those with public insurance or who identified as American Indian or Alaska Native were more likely to decline them.

The researchers also flagged a troubling development: As of late 2025, the Centers for Disease Control and Prevention stopped recommending routine hepatitis B vaccination for newborns. This move directly conflicts with American Academy of Pediatrics guidance and could leave families confused and more vulnerable to vaccine misinformation.

Further research into both the importance of these shots and the sex-based differences in refusal rates could help shape smarter awareness campaigns and evidence-based public health policies.

Written for you by our author Sanjukta Mondal, edited by Sadie Harley, and fact-checked and reviewed by Robert Egan—this article is the result of careful human work. We rely on readers like you to keep independent science journalism alive. If this reporting matters to you, please consider a donation (especially monthly). You'll get an ad-free account as a thank-you.

Publication details

Sarah A. Coggins et al, Parental Decline of Newborn Vitamin K and Hepatitis B Vaccine Administration by Newborn Sex, JAMA Network Open (2026). DOI: 10.1001/jamanetworkopen.2026.18410

Journal information: JAMA Network Open

Key medical concepts

Hepatitis B VaccineHepatitis BRetrospective Studies

Clinical categories

PediatricsChildren's healthPreventive medicineCommon illnesses & Prevention Who's behind this story?

Sanjukta Mondal

Master's in Chemistry. Freelance science journalist and communicator. Published in Chemistry World, BioSpace, and The Hindu. Full profile →

Sadie Harley

BSc Life Sciences & Ecology. Microbiology lab background with pharmaceutical news experience in oil, gas, and renewable industries. Full profile →

Robert Egan

Bachelor's in mathematical biology, Master's in creative writing. Well-traveled with unique perspectives on science and language. Full profile →

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Citation: Parents of newborn girls are more likely to refuse lifesaving vitamin K and hepatitis B vaccine shot, researchers find (2026, June 17) retrieved 17 June 2026 from https://medicalxpress.com/news/2026-06-parents-newborn-girls-lifesaving-vitamin.html This document is subject to copyright. Apart from any fair dealing for the purpose of private study or research, no part may be reproduced without the written permission. The content is provided for information purposes only.