Obstetric Anaesthesia Annual Scientific Meeting 2026

Introduction:

•Pregnancy Associated Cancer (PAC) is cancer diagnosed from conception to 1 year post-delivery

•PAC incidence is increasing, but reasons for this are poorly understood

We aimed to:

1.explore trends in PAC over time and by cancer type

2.define risk factors for PAC

Methods:

P: All deliveries from 1981-2023 in Scotland resulting in a livebirth

E: women with PAC

C: women without PAC

O: Crude incidence rate, risk factors

Statistics:

Univariable regression for risk factors.

Multivariable regression for risk factors with p<0.1

Mediation analysis (proportion of risk factors driving the increasing PAC incidence )

Results:

2,174,222 deliveries (2372 cases of PAC)

•228 (25.6%) antepartum, 661 (74.4%) postpartum PAC

•Most prevalent cancers: breast, melanoma, cervical

Crude incidence (Figure 1):1.09 per 1,000 deliveries

•1981: 0.35 per 1,000 deliveries

•2023: 1.41 per 1,000 deliveries

•Annual percentage increase: 2.9% (95% CI: 1.5 – 4.3%)

Risk factors for PAC:

•Univariable modelling: maternal age, least deprived SIMD, non-smoker, black ethnicity, nulliparity, BMI

•Multivariable modelling: maternal age only

•Mediation analysis (Figure 2): 43% of increasing PAC mediated by increasing maternal age.

Conclusions:

Pregnancy Associated Cancer:

•Incidence 1.09 per 1,000 deliveries per year

•Incidence increasing by 2.2% per year over 42 years

•Maternal age identified as a risk factor

•Increasing PAC incidence partially (43%) mediated by increasing maternal age

Pregnancy-Associated Cancer in Scotland (2007-2018): A retrospective population-based cohort study