Multifetal Pregnancies in Women with CKD: Risk Assessment and Indications for Counseling

KEY POINTS: CKD carries an increased risk for developing hypertensive disorders of pregnancy in multifetal pregnancies. CKD in multifetal pregnancies is associated with a shorter duration of gestation and an increased risk of having a baby small for gestational age. Multifetal pregnancies are a risk factor for hypertensive disorders of pregnancy compared with singleton gestations in patients living with CKD. BACKGROUND: CKD is a risk factor for adverse pregnancy outcomes in singleton pregnancies. Little is known about multifetal pregnancies in women with CKD. Owing to higher maternal age and the wider use of medically assisted fertilization, multifetal pregnancies are increasing. We aimed to review pregnancy outcomes in the largest multicenter series of multifetal pregnancies in women affected by CKD. METHODS: This retrospective study gathered data from three Italian units with long-standing experience in the follow-up of pregnancy in women with CKD (2000-2023). Propensity score-matched (age, parity, body mass index, year of delivery) multifetal low-risk pregnancies and singleton pregnancies served as controls; multifetal pregnancies were also matched for chorionicity, amnionicity, and mode of conception. Intrauterine death of at least one fetus, given the low number of events, was explored in the overall multifetal cohorts. RESULTS: In this propensity score matched-cohort study, 52 multifetal pregnancies in women with CKD were associated with a significantly lower gestational age compared with 104 low-risk non-CKD controls (median 34.0 versus 36.0 gestational weeks [GWs]) and with lower-term delivery rate (9.6% versus 28.8%). Neonatal intensive care unit admission was more frequent in multifetal pregnancies with CKD (50.9% versus 25.2%, P = 0.003). Cox regression and Kaplan-Meier analyses confirmed the independent effect of CKD on gestation duration. In women with CKD, multifetal pregnancies had a markedly shorter gestation than singletons (median 34 versus 39 GW, P < 0.00001), with significantly higher risk of preterm birth <34 GW (odds ratio [OR], 9.733), small for gestational age (OR, 5.155), and neonatal intensive care unit admission (OR, 8.033). The difference was sharper than in low-risk non-CKD pregnancies (35 and 39 GW, respectively). CONCLUSIONS: This study, the largest assessing the risks of adverse pregnancy outcomes in women with CKD carrying more than one fetus, suggests that multifetal gestation is a strong additional risk. These findings highlight the need for further investigation and demonstrate the importance of careful counseling, particularly in medically assisted reproduction.