Multimorbidity and Risk of Adverse Pregnancy Outcomes in a Safety-Net Hospital Cohort

It is well documented that single chronic conditions increase the risk of adverse pregnancy outcomes, but less is known about the impact of multiple chronic conditions in pregnancy. We assessed the association between multimorbidity and adverse pregnancy outcomes, including hypertensive disorders of pregnancy, gestational diabetes, intrapartum hemorrhage, placental abruption, prolonged length of hospital stay, stillbirth, preterm birth, and low birthweight.

We conducted a retrospective cohort study of 6,455 births using medical record data at a safety-net hospital (2015-2019). Multimorbidity was defined as having at least two diagnosis codes before or during pregnancy. Pregnancy outcomes were ascertained using clinical data and diagnosis codes. Log-binomial regression models using generalized estimating equations were fit to assess the association between multimorbidity and each outcome. We additionally stratified results by body mass index (BMI; <30 and ≥30 kg/m²) and describe the prevalence of adverse pregnancy outcomes by multimorbidity across racial and ethnic subgroups.

Multimorbidity affected more than one in three births (35.2%) and was associated with greater risks of hypertensive disorders of pregnancy (adjusted risk ratio [aRR], 1.26; 95% confidence interval [CI], 1.12, 1.41), preterm birth (aRR, 1.68; 95% CI, 1.47, 1.93), low birthweight (aRR, 1.61; 95% CI, 1.24, 2.09), stillbirth (RR, 1.84; 95% CI, 0.94, 3.60), placental abruption (aRR, 1.90; 95% CI, 1.00, 3.60), and prolonged hospital stay for cesarean (aRR, 1.40; 95% CI, 1.11, 1.77) and vaginal (aRR, 1.26; 95% CI, 1.07, 1.48) births, compared with individuals without multimorbidity. Further, greater risks of hypertensive disorders of pregnancy (aRR, 1.64; 95% CI, 1.37, 1.96) and gestational diabetes (aRR, 2.58; 95% CI, 1.86, 3.59) were found among those with multimorbidity and a co-occurring BMI of ≥30 kg/m² compared with those with multimorbidity with a BMI of <30 kg/m². Most adverse pregnancy outcomes were more frequent among patients with multimorbidity who identified as non-Hispanic Black and Hispanic/Latine and less frequent among white patients with multimorbidity.

The high prevalence of multimorbidity and its association with adverse pregnancy outcomes highlight the importance of collaborative approaches for preconception and pregnancy care to optimize perinatal health.