Interpregnancy interval and hypertensive disorders of pregnancy: A population‐based cohort study. Issue 4 (19th March 2020)

• Record Type: Journal Article
• Authors: Gebremedhin, Amanuel T.; Regan, Annette K.; Ball, Stephen; Betrán, Ana P.; Foo, Damien; Gissler, Mika; Håberg, Siri E.; Malacova, Eva; Marinovich, Michael Luke; Pereira, Gavin
• Other Names: Ahrens Katherine guestEditor.; Hutcheon Jennifer guestEditor.
• Is Part Of: Paediatric and perinatal epidemiology. Volume 35:Issue 4(2021)
• Page Start: 404
• Page End: 414
• Publication Date: 2020-03-19
• Subjects: birth spacing -- hypertensive disorders of pregnancy -- interpregnancy interval -- pregnancy complications -- within‐mother; Pediatrics -- Periodicals; Perinatology -- Periodicals; Pediatric epidemiology -- Periodicals; Infants (Newborn) -- Diseases -- Periodicals; 618.92
• DOI: 10.1111/ppe.12668
• Languages: English
• ISSNs: 0269-5022

Abstract

Abstract: Background: Despite extensive research on risk factors and mechanisms, the extent to which interpregnancy interval (IPI) affects hypertensive disorders of pregnancy in high‐income countries remains unclear. Objectives: To examine the association between IPI and hypertensive disorders of pregnancy in a high‐income country setting using both within‐mother and between‐mother comparisons. Methods: A retrospective population‐based cohort study was conducted among 103 909 women who delivered three or more consecutive singleton births (n = 358 046) between 1980 and 2015 in Western Australia. We used conditional Poisson regression with robust variance, matching intervals of the same mother and adjusted for factors that vary within‐mother across pregnancies, to investigate the association between IPI categories (reference 18‐23 months), and the risk of hypertensive disorders of pregnancy. For comparison with previous studies, we also applied unmatched Poisson regression (between‐mother analysis). Results: The incidence of preeclampsia and gestational hypertension during the study period was 4%, and 2%, respectively. For the between‐mother comparison, mothers with intervals of 6‐11 months had lower risk of preeclampsia with adjusted relative risk (RR) 0.92 (95% confidence interval [CI] 0.85, 0.98) compared to reference category of 18‐23 months. With the within‐mother matched design, we estimated a larger effect of long IPI on risk of preeclampsia (RR 1.29, 95% CI 1.18, 1.42 for 60‐119 months; and RR 1.30, 95% CI 1.10, 1.53 for intervals ≥120 months) compared to 18‐23 months. Short IPIs were not associated with hypertensive disorders of pregnancy. Conclusions: In our cohort, longer IPIs were associated with increased risk of preeclampsia. However, there was insufficient evidence to suggest that short IPIs (<6 months) increase the risks of hypertensive disorders of pregnancy.