Adverse Obstetric Outcomes in Pregnancies With Major Fetal Congenital Heart Defects.

Importance: Understanding the risk profile of obstetric complications in pregnancies with fetal major congenital heart defects (MCHDs) is crucial for obstetric counseling and care. Objective: To investigate the risk of placenta-related adverse obstetric outcomes in pregnancies complicated by fetal MCHDs. Design, Setting, and Participants: This cohort study retrieved data from June 1, 2008, to June 1, 2018, from the Danish Fetal Medicine Database, which includes comprehensive data on more than 95% of all pregnancies in Denmark since the database was instituted in 2008. All singleton pregnancies that resulted in a live-born child after 24 weeks' gestation without chromosomal aberrations were included. A systematic search of the literature was performed in PubMed, Embase, and the Cochrane Library from inception to June 1, 2024, to compile existing knowledge and data on adverse obstetric outcomes among MCHD subtypes. Exposure: Fetal MCHDs including 1 of 11 subtypes. Main Outcomes and Measures: The primary outcome was a composite adverse obstetric outcome defined as preeclampsia, preterm birth, fetal growth restriction, or placental abruption. Secondary outcomes consisted of each adverse obstetric event. Adjusted odds ratios (AORs) were computed using generalized estimating equations adjusted for maternal body mass index, age, smoking, and year of delivery. Meta-analyses were conducted using random-effects models to pool effect sizes for each MCHD subtype and adverse obstetric outcome. Results: A total of 534 170 pregnancies were included in the Danish cohort, including 745 with isolated fetal MCHDs (median [IQR] maternal age, 29.0 [26.0-33.0] years) and 533 425 without MCHDs (median [IQR] maternal age, 30.0 [26.0-33.0] years). Pregnancies with fetal MCHDs exhibited a higher rate of adverse obstetric outcomes at 22.8% compared with 9.0% in pregnancies without fetal MCHDs (AOR, 2.96; 95% CI, 2.49-3.53). Preeclampsia (AOR, 1.83; 95% CI, 1.33-2.51), preterm birth at less than 37 weeks (AOR, 3.84; 95% CI, 3.15-4.71), and fetal growth restriction (AOR, 3.25; 95% CI, 2.42-4.38) occurred significantly more frequently in pregnancies with MCHDs. Except for fetal transposition of the great arteries (AOR, 1.19; 95% CI, 0.66-2.15), all MCHD subtypes carried a greater risk of adverse obstetric outcomes. The meta-analysis included 10 additional studies that supported these results. Conclusions and Relevance: These findings suggest that nearly 1 in 4 women expecting a child with an MCHD, except transposition of the great arteries, may be at high risk of adverse obstetric outcomes.