Risk of Hypertensive Disorders in Pregnancy After Fresh and Frozen Embryo Transfer in Assisted Reproduction: A Population-Based Cohort Study With Within-Sibship Analysis. Issue 2 (26th September 2022)

• Record Type: Journal Article
• Authors: H. Petersen, Sindre; Westvik-Johari, Kjersti; Spangmose, Anne Lærke; Pinborg, Anja; Romundstad, Liv Bente; Bergh, Christina; Åsvold, Bjørn Olav; Gissler, Mika; Tiitinen, Aila; Wennerholm, Ulla-Britt; Opdahl, Signe
• Is Part Of: Hypertension. Volume 80:Issue 2(2022)
• Page Start: e6
• Page End: e16
• Publication Date: 2022-09-26
• Subjects: cryopreservation -- embryo transfer -- fertilization in vitro -- hypertension -- pre-eclampsia -- pregnancy -- siblings; Hypertension -- Periodicals; Hypertension -- Treatment -- Periodicals; 616.132005
• DOI: 10.1161/HYPERTENSIONAHA.122.19689
• Languages: English
• ISSNs: 0194-911X

Abstract

Abstract : Background: Frozen embryo transfer (frozen-ET) is increasingly common because of improved cryopreservation methods and elective freezing of all embryos. Frozen-ET is associated with higher risk of hypertensive disorders in pregnancy than both natural conception and fresh embryo transfer (fresh-ET), but whether this is attributable to parental factors or treatment is unknown. Methods: Using the Medical Birth Registries of Denmark (1994–2014), Norway, and Sweden (1988–2015), linked to data from national quality registries and databases on assisted reproduction, we designed a population-based cohort study with within-sibship comparison. We included 4 426 691 naturally conceived, 78 300 fresh-ET, and 18 037 frozen-ET singleton pregnancies, of which 33 209 sibships were conceived using different conception methods. Adjusted odds ratios (aOR) of hypertensive disorders in pregnancy for fresh-ET and frozen-ET versus natural conception with 95% CI were estimated using multilevel logistic regression, where random effects provided conventional population-level estimates and fixed effects gave within-sibship estimates. Main models included adjustment for birth year, maternal age, parity, and country. Results: Risk of hypertensive disorders in pregnancy was higher after frozen-ET compared to natural conception, both at population-level (7.4% versus 4.3%, aOR, 1.74 [95% CI, 1.61–1.89]) and within sibships (aOR, 2.02 [95% CI, 1.72–2.39]). For fresh-ET, risk was similar to natural conception, both at population-level (aOR, 1.02 [95% CI, 0.98–1.07]) and within sibships (aOR, 0.99 [95% CI, 0.89–1.09]). Conclusions: Frozen-ET was associated with substantially higher risk of hypertensive disorders in pregnancy, even after accounting for shared parental factors within sibships.