National survey data from Papua New Guinea (PNG) suggest that women are having almost 1.5 times the number of children they desire. Women’s ability to space and limit the number of children could have a significant impact on the country’s high infant and maternal mortality rates.

To determine the prevalence and demographic associations of unintended pregnancy in women presenting for antenatal care to Port Moresby General Hospital.

From November 2011 to February 2012, we administered a structured questionnaire to women attending antenatal clinics covering pregnancy intention, contraceptive use and demographic information.

Amongst the 1198 respondents, 49.4% of the pregnancies were reported as unintended with significantly higher proportions amongst women with no education or education only to primary school level (OR:1.46, CI: 1.10–1.92), unmarried women (OR:7.16, CI: 4.08–12.58), women whose first sexual encounter was under the age of 20 (OR 1.55, CI: 1.20–1.99) and women with three or more children compared to those having their first child (OR: 2.70, CI:1.86–3.93). Amongst multiparous women, a short birth interval of less than two years was significantly associated with unintended pregnancy (P < 0.001). Conclusions Unintended pregnancy was common and occurred more frequently amongst women who already had three or more children, often leading to birth spacing of under two years. There is a need for effective programs and strategies to increase access to contraceptive information and services. Immediate provision of long‐acting reversible contraceptive methods in the postnatal period could facilitate such access and reduce unplanned pregnancy amongst multiparous women.