Background
Hepatitis B virus (HBV) immunisation is the first vaccine of infant life and one of the most commonly refused immunisations on the Australian Immunisation Schedule.

Aims
To quantify the frequency of declined HBV immunisation birth‐doses, investigate reasons for refusal, and determine information sources used by parents.

Materials and Methods
A cross‐sectional study using a questionnaire was conducted on postnatal women who declined their newborn’s HBV birth‐dose immunisation during December 2016–July 2017 at an Australian tertiary referral hospital. Mothers who were non‐English‐speaking, unwell or medically unstable, or otherwise unavailable were excluded.

Results
One hundred and thirty‐seven of the 1574 (8.7%) eligible reviewed infants had HBV immunisation birth‐doses documented as declined; 113 mothers consented to complete the questionnaire. The most common reasons for declining the dose were: ‘baby too young’ (55.8%); preference for two, four and six‐month HBV immunisations only (56.6%); perceived low risk of contracting HBV (45.1%); and a fear of ‘overloading’ their baby’s immune system (42.5%). General practitioners or nurses/midwives (43.3%) and the internet/media (33.6%) were the predominant information sources consulted, and 58.4% felt satisfied with the information they received antenatally. Eighty‐eight of 113 mothers (77.9%) would still consider future immunisations for their infant.

Conclusions
The majority of postnatal women decline HBV birth‐dose immunisation for their newborns citing age‐related safety concerns and vaccine misconceptions. Informal information sources such as the internet and media are often consulted. Addressing the need for antenatal and health professional education toward the birth‐dose may be instrumental in improving uptake.