LAUSR

OBJECTIVE To determine how a shift in clinical practice along with laboratory changes has impacted singleton perinatal outcomes after autologous in vitro fertilization (IVF) cycles. DESIGN Retrospective cohort. SETTING Single academic fertility clinic. PATIENT(S) Singleton live births resulting from all IVF cycles (n = 14,424) from August 1, 1995 to October 31, 2019. INTERVENTION(S) None. MAIN OUTCOME MEASURE(S) Live birth weight, large for gestational age (GA), small for GA, and preterm birth. RESULT(S) The entire cohort consisted of 9,280 fresh and 5,144 frozen IVF cycles. Maternal age, parity, body mass index, neonatal sex, and GA at delivery were similar in both groups. There was a decrease in adjusted birth weight per year over the study period for the entire cohort of IVF cycles (-4.42g, 95% confidence interval [CI]: -6.63g to -2.22g). Rates of large for GA newborns decreased by 1.7% (95% CI: 2.9% to 0.6%) annually across the entire cohort of IVF cycles. Furthermore, there was a decrease in annual rates of preterm birth before 32 weeks by 3.2% (95% CI: 5.9% to 0.5%) across the entire cohort of IVF cycles. Trends were also seen in annual reduction of rates of preterm birth before 37 and 28 weeks. CONCLUSION(S) With the gradual evolution of clinical and IVF laboratory practices, there has been a decrease in birth weight over 24 years for the entire cohort of IVF cycles. Concurrently, noteworthy practice changes have resulted in an improvement in IVF outcomes with decreased rates of large for GA newborns and preterm birth before 32 weeks for the entire cohort of IVF cycles.