Perinatal outcomes among young donor oocyte recipients

Abstract

Study question: Is the use of donor oocytes in women <35 years of age associated with an increased risk of adverse perinatal outcomes compared to use of autologous oocytes?

Summary answer: Among fresh assisted reproductive technology (ART) cycles performed in women under age 35, donor oocyte use is associated with a higher risk of preterm birth, low birth weight and stillbirth (when zero embryos were cryopreserved) as compared to autologous oocytes.

What is known already: Previous studies demonstrated elevated risk of poor perinatal outcomes with donor versus autologous oocytes during ART, primarily among older women.

Study design, size, duration: Retrospective cohort study using data reported to Centers for Disease Control and Prevention's National ART Surveillance System (NASS) during the period from 2010 to 2015 in order to best reflect advances in clinical practice. Approximately 98% of all US ART cycles are reported to NASS, and discrepancy rates were <6% for all fields evaluated in 2015.

Participants/materials, setting, methods: We included all non-banking fresh and frozen ART cycles performed between 2010 and 2015 in women under age 35 using autologous or donor eggs. Cycles using cryopreserved eggs, donated embryos or a gestational carrier were excluded. Among fresh embryo transfer cycles, we calculated predicted marginal proportions to estimate the unadjusted and adjusted risk ratios (aRRs) and 95% confidence intervals (CIs) for the association between donor versus autologous oocyte use and stillbirth, spontaneous abortion, preterm delivery and low birth weight among singleton pregnancies or births. Stillbirth models were stratified by number of embryos cryopreserved. All models were adjusted for patient and treatment characteristics.

Main results and the role of chance: Among the 71 720 singleton pregnancies occurring during 2010-2015, singletons resulting from donor oocytes were more likely to be preterm (15.6% versus 11.0%; aRRs 1.39: CI 1.20-1.61) and have low birth weight (11.8% versus 8.8%; aRRs 1.34; CI 1.16-1.55) than those resulting from autologous oocytes. With zero embryos cryopreserved, donor versus autologous oocyte use was associated with increased risk for stillbirth (2.1% versus 0.6%; aRRs 3.73; CI 1.96-7.11); no association with stillbirth was found when ≥1 embryo was cryopreserved (0.54% versus 0.56%; aRR 1.15; CI 0.59-2.25).

Limitations, reasons for caution: The data come from a national surveillance system and is thus limited by the accuracy of the data entered by individual providers and clinics. There may be unmeasured differences between women using donor eggs versus their own eggs that could be contributing to the reported associations. Given the large sample size, statistically significant findings may not reflect clinically important variations.

Wider implications of the findings: Risks of preterm birth, low birth weight and stillbirth among singleton pregnancies using donor oocytes were increased compared to those using autologous oocytes. Further study regarding the pathophysiology of the potentially increased risks among donor oocyte recipient pregnancy is warranted.

Study funding/competing interest(s): None.

Trial registration number: N/A.

Keywords: donor oocyte; low birth weight; perinatal outcomes; preterm; stillbirth; young recipient.

Figure 1

The absolute number of donor oocyte cycles and donor oocyte cycles as percent of all US ART cycles among women <35 years old.