Association between preterm birth subtypes and severe maternal morbidity: a retrospective cohort study

Area of Science:

• Obstetrics and Gynecology
• Maternal-Fetal Medicine
• Public Health

Background:

• Severe maternal morbidity (SMM) is a critical complication of preterm delivery.
• Existing research often overlooks SMM variations by preterm birth subtype and postpartum outcomes.

Purpose of the Study:

• To investigate the association between preterm birth subtypes and SMM during delivery hospitalization.
• To examine SMM up to one year postpartum and postpartum readmissions within 365 days.

Main Methods:

• Retrospective cohort study utilizing linked birth/fetal death certificates and maternal hospital discharge data (2008-2020).
• Modified Poisson regression models estimated adjusted relative risks (aRR) for SMM and readmissions, stratified by preterm birth subtype.
• Adjusted for demographic and prenatal care factors.

Main Results:

• Medically indicated preterm births showed significantly higher SMM risks during hospitalization (aRR 6.7-18.0) and postpartum (aRR 2.1-3.4) compared to spontaneous preterm births (aRR 3.1-7.5 and 1.6-2.0, respectively).
• Elevated postpartum SMM risks persisted across all preterm subtypes and gestational ages.
• Increased postpartum readmission risks were observed for both spontaneous and medically indicated preterm births.

Conclusions:

• Preterm delivery, especially when medically indicated, is strongly linked to increased SMM during delivery, postpartum, and readmissions.
• Patients with medically indicated preterm births may benefit from enhanced postpartum monitoring and earlier clinical follow-up.
• Current postpartum surveillance may need expansion beyond the standard 6-week visit for preterm birth patients.