Pregnancy associated cancer, timing of birth and clinical decision making—a NSW data linkage study

BACKGROUND: The incidence of pregnancy-associated cancer (PAC), comprising cancer diagnosed during pregnancy or within one year postpartum, is increasing. We investigated the obstetric management and outcomes of women with PAC and their babies. METHODS: A population-based observational study of all women who gave birth between 1994 and 2013 in New South Wales, Australia. Women were stratified into three groups: those diagnosed during pregnancy (gestational cancer group), those diagnosed within one year of giving birth (postpartum cancer group), and a no-PAC group. Generalized estimating equations were used to examine the association between PAC and adverse maternal and neonatal outcomes. RESULTS: One million seven hundred eighty-eight thousand four hundred fifty-onepregnancies were included—601 women (614 babies) were in the gestational cancer group, 1772 women (1816 babies) in the postpartum cancer group, and 1,786,078 women (1,813,292 babies) in the no-PAC group. The overall crude incidence of PAC was 132.7/100,000 women giving birth. The incidence of PAC increased significantly over the twenty-year study period from 93.5/100,000 in 1994 to 162.5/100,000 in 2013 (2.7% increase per year, 95% CI 1.9 – 3.4%, p-value < 0.001). This increase was independent of maternal age. The odds of serious maternal complications (such as acute abdomen, acute renal failure, and hysterectomy) were significantly higher in the gestational cancer group (adjusted odds ratio (AOR) 5.07, 95% CI 3.72 – 6.90) and the postpartum cancer group (AOR 1.55, 95% CI 1.16 – 2.09). There was no increased risk of perinatal mortality in babies born to women with PAC. However, babies of women with gestational cancer (AOR 8.96, 95% CI 6.96 – 11.53) or postpartum cancer (AOR 1.36, 95% CI 1.05 – 1.81) were more likely to be planned preterm birth. Furthermore, babies of women with gestational cancer had increased odds of a severe neonatal adverse outcome (AOR 3.13, 95% CI 2.52 – 4.35). CONCLUSION: Women with PAC are more likely to have serious maternal complications. While their babies are not at increased risk of perinatal mortality, they are more likely to experience poorer perinatal outcomes associated with preterm birth. The higher rate of birth intervention among women with gestational cancers reflects the complexity of clinical decision-making in this context. SUPPLEMENTARY INFORMATION: The online version contains supplementary material available at 10.1186/s12884-023-05359-1.