Abstract
Objective Among patients ≥45 years, the birth rate in the United States continues to increase. As fertility declines with age, this cohort often utilizes assisted reproductive technology, specifically in vitro fertilization (IVF). While both advancing maternal age and IVF are independently associated with adverse maternal outcomes, data regarding their additive effect are scant. This article aims to determine if patients who conceive via IVF are at increased risk for preterm birth (PTB) compared to patients with non-IVF pregnancies in a very advanced maternal age (vAMA) cohort (≥45 years).
Study Design Retrospective cohort study of all pregnant patients ≥45 years old who delivered at a single institution (2014–2021). Those with incomplete delivery/neonatal records or multiples beyond twins were excluded. We compared individuals who conceived via IVF to those who conceived without IVF. The primary outcome was preterm delivery <37 weeks gestation. Secondary outcomes included other adverse perinatal outcomes. Using multivariable logistic regression, we adjusted for multiple gestation as well as confounders found to be significantly different in the univariable analysis and other known risk factors for PTB.
Results In our study cohort of 420 vAMA patients, individuals who underwent IVF were more likely to be older, privately insured, nulliparous, and with a twin gestation. The PTB rate in vAMA patients who underwent IVF was 24.4 compared to 8.4% in patients who did not use IVF (p < 0.001). After adjusting for confounders, IVF was an independent risk factor for PTB <37 weeks in vAMA patients (adjusted odds ratio {aOR] = 4.3, 95% confidence interval [CI]: 1.7–10.4, p = 0.001). In vitro fertilization was also associated with a composite of adverse maternal outcomes (hypertensive disorder of pregnancy, postpartum hemorrhage, blood transfusion, and unplanned hysterectomy) (aOR = 1.7, 95% CI: [1.1–2.9], p = 0.03).
Conclusion In the vAMA population, conception via IVF is associated with an increased risk of PTB <37 weeks.
Key Points
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This study examines IVF as an independent risk factor for PTB in patients ≥45 years at delivery, which has not been specifically addressed in prior studies.
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In vAMA patients, use of IVF is associated with an increased risk of PTB <37 weeks. These patients also have higher rates of cesarean delivery. Neonates from IVF pregnancies are more likely to be very low birth weight or low birth weight.
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Bodies of research exist for both advanced maternal age and assisted reproductive technology, there is a paucity of data specifically in parturients of vAMA who conceive via IVF.
Keywords
advanced maternal age - assisted reproductive technology - in vitro fertilization - preterm birth - very advanced maternal age
