Stillbirth rates and their determinants in a national maternity hospital in Phnom Penh, Cambodia in 2017–2020: a cross-sectional assessment with a nested case–control study

BACKGROUND: In Cambodia, stillbirths and their underlying factors have not been systematically studied. This study aimed to assess the proportion and trends in stillbirths between 2017 and 2020 in a large maternity referral hospital in the country and identify their key determinants to inform future prevention efforts. METHODS: This was a retrospective cross-sectional analysis with a nested case–control study of women giving birth at the National Maternal and Child Health Centre (NMCHC) in Phnom Penh, 2017–2020. We calculated percentages of singleton births at ≥ 22 weeks’ gestation resulting in stillbirth and annual stillbirth rates by timing: intrapartum (fresh) or antepartum (macerated). Multivariable logistic regression was used to explore factors associated with stillbirth, where cases were all women who gave birth to a singleton stillborn baby in the 4-year period. One singleton live birth immediately following each case served as an unmatched control. Multiple imputation was used to handle missing data for gestational age. RESULTS: Between 2017 and 2020, 3.2% of singleton births ended in stillbirth (938/29,742). The stillbirth rate increased from 24.8 per 1000 births in 2017 to 38.1 per 1000 births in 2020, largely due to an increase in intrapartum stillbirth rates which rose from 18.8 to 27.4 per 1000 births in the same period. The case–control study included 938 cases (stillbirth) and 938 controls (livebirths). Factors independently associated with stillbirth were maternal age ≥ 35 years compared to < 20 years (aOR: 1.82, 95%CI: 1.39, 2.38), extreme (aOR: 3.29, 95%CI: 2.37, 4.55) or moderate (aOR: 2.45, 95%CI: 1.74, 3.46) prematurity compared with full term, and small-for-gestational age (SGA) (aOR: 2.32, 1.71, 3.14) compared to average size-for-age. Breech/transverse births had nearly four times greater odds of stillbirth (aOR: 3.84, 95%CI: 2.78, 5.29), while caesarean section reduced the odds by half compared with vaginal birth (aOR: 0.50, 95%CI: 0.39, 0.64). A history of abnormal vaginal discharge increased odds of stillbirth (aOR: 1.42, 95%CI: 1.11, 1.81) as did a history of stillbirth (aOR: 3.08, 95%CI: 1.5, 6.5). CONCLUSIONS: Stillbirth prevention in this maternity referral hospital in Cambodia requires strengthening preterm birth detection and management of SGA, intrapartum care, monitoring women with stillbirth history, management of breech births, and further investigation of high-risk referral cases. SUPPLEMENTARY INFORMATION: The online version contains supplementary material available at 10.1186/s12978-023-01703-y.