Title : Recurrence risk of preterm birth in successive pregnancies based on its subtypes
Abstract:
Objective: Although a prior history of preterm birth (PTB) is a potential risk factor for recurrence in successive pregnancies, little information is available on whether recurrence risk is modified by race/ethnicity, gestational age at birth, PTB subtypes, and interpregnancy intervals (IPI); therefore, we examined whether PTB recurrence risk is modified by these factors.
Methods: A retrospective cohort study of singleton pregnancies in Kaiser Permanente Southern California (2009-2022) using data extracted from electronic health records (EHR) on first 2 (n= 82,610) and 3 (n=14,925) pregnancies. Data on preterm labor triage extracted from EHRs by implementing Natural Language Processing were used to define PTB subtypes (spontaneous PTB [sPTB] and iatrogenic PTB [iPTB]). Logistic regression models were used to estimate adjusted odds ratios (aOR) and their 95% Confidence Intervals (CI).
Results: A first pregnancy complicated by PTB was associated with 6-fold increased risk of PTB in the second pregnancy compared with a first uncomplicated pregnancy (23.29% vs. 4.98%, respectively; aOR, 5.60, 95% confidence intervals [CI]: 5.23-5.99). Stratified by their subtypes, those with a history of sPTB (aOR: 5.32, 95% CI 4.87, 5.81) and iPTB (aOR: 8.26, 95% CI 7.18, 9.50) had increased risk for the same respective subtype at their second pregnancy. PTB recurrence risk persisted across race/ethnicity and PTB subtypes with the highest risks observed for iPTB. Compared to pregnancies without PTB in the first two pregnancies (4.58%), those with PTB in both pregnancies (40.94%) were associated with significantly increased PTB risk in their third pregnancy (aOR, 14.59; 95% CI, 11.28-18.88). The recurrence of PTB between 1st and 2nd pregnancy was substantially higher for those who delivered in 20-33 weeks of gestation, regardless of PTB subtype. Risk of both sPTB and iPTB recurrence in successive pregnancies were not related to the length of IPI or pre-pregnancy BMI categories. Non-Hispanic Blacks and Asian/Pacific Islanders had a higher recurrence risk in both subtypes of PTB when compared to their non-Hispanic White counterpart.
Conclusion: We observed significant disparities in recurrent PTB by their subtypes and maternal race/ethnicity among a large integrated healthcare system in Southern California. In women with a previous sPTB, a short IPI has a strong impact on the risk of recurrence in the second pregnancy.
Audience Take Away:
- Learn more about the recurrence risk of spontaneous vs iatrogenic preterm birth.
- Use of Natural Language Processing to ascertain preterm birth subtypes.
- Data on health inequities in preterm birth.
