Dynamic view of assisted reproduction in Turkey from 1996 to 2020.

Research Question: What are the trends and changes in patient demographics and practices in treatment with assisted reproductive technology (ART) in Turkey over 25 years?

Design: Data on patient demographics, cycle characteristics and clinical outcome of 29,541 cycles in 22,867 women who underwent treatment with ART between 1996 and 2020 were analysed according to calendar years. Regression and interrupted time series analysis were used to assess changes in patient characteristics, trends and effects of interventions on outcome.

Results: From 1996 to 2020, the average age of women undergoing treatment with ART increased from 32.1 to 36.0 years (r = 0.96), the proportion of women over 40 more than tripled (9% versus 28.7%; r = 0.97) and the average duration of infertility at presentation dropped from 8.4 to 4 years (r = -0.98) (P < 0.0001, for all). Diminished ovarian reserve became the major indication by 2015. Gonadotrophin-releasing hormone antagonists dominated ovarian stimulation by 2009. The average number of oocytes retrieved decreased from 11.5 to 7.8 (r = -0.86, P < 0.0001). Blastocyst-stage transfers gradually increased, comprising 51% of all transfers in 2020 (r = 0.86, P < 0.0001). The mean number of embryos transferred decreased from 3.9 to 1.5. Clinical pregnancy rates (CPR) per embryo transfer remained stable for fresh transfers (range: 31.6-43.9%) but increased from 13% to 30.3% in cryopreserved transfers. The estimate of effect of blastocyst vitrification was significant (P = 0.001). The multiple birth rate declined from 30.4% to 7.1%.

Conclusions: Remarkable changes were seen in patient demographics, treatment indications, and clinical and laboratory practices. Increased use of single embryo transfer and improvements in cryopreservation techniques helped maintain high CPR while reducing multiple births.