341: Non-communicable diseases and the risk of hypertensive disorders of pregnancy

Abstract

The non-communicable diseases of pregnancy, mainly pre-existing Diabetes (D), Obesity (O) and Hypertension (H) are a growing concern and associated with perinatal morbidity. We determined the relation between D-O-H, alone, and in combination, and hypertensive disorders of pregnancy (HDP). This population-based cohort study comprised all singleton hospital births in Ontario, Canada, occurring at > 20 weeks’ gestation, from April 2012 to March 2016. Data were collected in a standardized manner within the Better Outcomes Registry & Network information system. Rates of preeclampsia (PE), PE < 32 weeks (for D,O and H) and gestational hypertension (GH) (for D and O) were calculated according to various combinations of D-O-H. Multivariable Poisson regression with robust error variance was used to calculate crude and adjusted relative risks (RR) and 95% confidence intervals (CIs). Population attributable fractions (PAF) and 95% CIs for HDP were also calculated, to estimate the proportion of HDP that could be potentially prevented if D, O and/or H were hypothetically eliminated. Of 497,535 singleton deliveries > 20 weeks, 94,009 (18.89%) had pre-existing diabetes, obesity or hypertension (DOH) in isolation or combined. There were a total of 21,823 pregnancies complicated by HDP, 9597 (44.0%) of which occurred in the DOH group. Relative to women without D, O or H, the risk of HDP was significantly higher in women with D-O-H, with the highest risk found in H (aRR=47.55; 44.23-51.12) and DOH combined (aRR=65.11; 56.82-74.6). Amongst the individual components of DOH, the risk of PE was highest in H (aRR = 47.55; .81; 44.23 - 51.12) and D [aRR =4.69; 3.79-5.8) and lowest in O (aRR = 2.13; 1.98-2.28). For PE < 32 weeks, D was not associated with increased risk but O and H retained significance (Fig. 1). D-O-H, in any combination, had a PAF of 35.36% (95% CI 34.61-36.1) for all HDP, and an even higher PAF of 42.75% (95% CI 41.21-44.24) for PE. Pre-pregnancy D-O-H significantly increases the risk of HDP and disproportionately contributes to hypertensive morbidity in pregnancy.