The impact of single-step and sequential embryo culture systems on obstetric and perinatal outcomes in singleton pregnancies: the Massachusetts Outcomes Study of Assisted Reproductive Technology

Objective: To compare the obstetric and perinatal outcomes of deliveries conceived with embryos from single-step vs. sequential culture media systems.

Design: Historical cohort of Massachusetts vital records linked to assisted reproductive technology clinic data from the Society for Assisted Reproductive Technology Clinic Outcome Reporting System and laboratory embryology data from two large academic hospital fertility centers.

Setting: Not applicable.

Patients: Patients with singleton live birth deliveries between 2004 and 2017 conceived with autologous assisted reproductive technology cycles with fresh blastocyst transfer using either single-step (n = 1,058) or sequential (n = 474) culture media systems.

Interventions: None.

Main outcome measures: Associations of single-step vs. sequential culture with obstetric outcomes (mode of delivery, placental abnormalities, pregnancy-induced hypertension, and gestational diabetes) and perinatal outcomes (preterm birth, low birthweight, small-for-gestational-age, and large-for-gestational-age [LGA]) were assessed with multivariate logistic modeling, adjusted for maternal age, race/ethnicity, education, parity, insurance type, protein supplementation, oxygen concentration, fertilization method, and number of transferred embryos.

Results: Compared with sequential culture, single-step culture was associated with increased odds of LGA (adjusted odds ratio 2.1, 95% confidence interval 1.04-4.22). There were no statistically significant differences between single-step and sequential culture media systems in the odds of placental abnormalities, pregnancy-induced hypertension, gestational diabetes, prematurity, small-for-gestational-age, or low birthweight.

Conclusions: Single-step culture is associated with increased odds of LGA, indicating that embryo culture media systems may affect perinatal outcomes.