(947) Trends of hypertensive disorders of pregnancy among preterm births in the United States

Friday, February 10, 2023

3:30 PM – 5:00 PM

Objective: Hypertensive disorders of pregnancy (HDP), a common obstetric complication and a leading cause of maternal morbidity and mortality, is also highly associated with preterm birth (PTB). Contemporary data on the prevalence of HDP among patients with PTB is lacking. This study seeks to explore potential association between HDP and PTB.

Study Design: PTBs ( < 37 weeks) were identified from the National Vital Statistics System and stratified by the occurrence of HDP composite (HDP and eclampsia). Trends in HDP by degree of PTB (defined by World Health Organization classification) were investigated using joinpoint regression, estimating an annual average percent change (AAPC). Multivariable logistic regression models were fit assessing the relationship between birth year and outcomes of HDP composite, HDP only, and eclampsia only, adjusting for demographic and clinical factors.

Results: From 2015-2020, 2.6 million PTB cases were identified with 73.9% late moderate preterm (34-36 weeks), 12.1% early moderate preterm (32-33 weeks), 9.4% moderate preterm (28-31 weeks), and 4.6% extremely preterm ( < 28 weeks). HDP prevalence among PTB increased from 13.6% to 19.3% (AAPC 5.9%, 95% CI: 5.3%, 6.4%), with the largest increase among late moderate PTB (12.9% to 18.9%; AAPC 6.5%, 95% CI: 5.9%, 7.1%) followed by early moderate PTB (16.4% to 21.0%; AAPC 4.9%, 95% CI: 4.0%, 5.7%) (Figure). Extreme PTB (11.1% to 14.4%; AAPC 4.1%, 95% CI: 2.9%, 5.4%) and moderate PTB (16.4% to 21.0%; AAPC 3.0%, 4.6%) increased modestly in comparison during the study period. Adjusted analyses noted an increasing likelihood of the HDP composite occurring in recent years (Table). This increased likelihood of the HDP composite with recent years was evident in the HDP only analysis, whereas no trend was noted in the eclampsia only analysis (Table).

Conclusion: Our findings note an upward trend of HDP prevalence among later PTBs, suggesting an increasing burden of HDP on patients with PTB. Improvements in risk stratification and identification in early pregnancy are necessary to better predict and target interventions to decrease these burdens.

Primary & Presenting Author(s)

Anna Buford, BA (she/her/hers)
UT Southwestern Medical School
Dallas, Texas, United States

Coauthor(s)
IF
Isabel Fulcher, PhD
Vice President of Data Science
Delfina Care Inc.
San Francisco, California, United States

AE
Ali Ebrahim, PhD
Delfina Care Inc.
San Francisco, California, United States

SE
Senan Ebrahim, MD, PhD
Delfina Care Inc.
San Francisco, California, United States

Timothy Wen, MD,MPH (he/him/his)
Clinical Fellow
University of California, San Francisco
San Francisco, California, United States