P-727 The demographic impact of increasing ART use on fertility - the case of Czechia

Abstract Study question What is the contribution of ART usage to the recent fertility trends - the total fertility rate (TFR) and birth timing - in Czechia? Summary answer The results revealed the contribution of the increasing use of ART to the ongoing childbearing postponement process. What is known already The demographic importance of the use of ART has increased substantially over the last two decades in the context of the ongoing fertility postponement process. The use of ART is likely to reduce involuntary childlessness and helps to offset part of the effect of increasing infertility due to fertility postponement. However, its use cannot make up for all births lost by the natural decline in fertility after age 35. The use of ART pushes the age limits of childbearing to extremely late ages. Moreover, ART may serve to create the illusion that childbearing can be postponed until late reproductive ages. Study design, size, duration The study is based on anonymised individual data from national health registers managed by the Institute of Health Information and Statistics and data available from the Czech Statistical Office. A unique database of individual data on each child born in the years 2013-2018 in Czechia allows the construction of detailed demographic fertility indicators in terms of the use/non-use of ART. Participants/materials, setting, methods The study employs demographic indicators characterising the level of fertility and its timing (total fertility rate, age-specific fertility rates, mean age of mothers at childbirth). These indicators are constructed using data for live births and are further disaggregated by whether or not the mother has undergone ART. Main results and the role of chance Both the number and the proportion of live births following ART increased steadily between 2013 and 2018. The proportions of ART-live births increased significantly with the age of the mothers (around 5% of children were born following ART to mothers aged 35-39 years, less than 10% to mothers aged 40-44, almost 40% to mothers aged 45-49 years). The ART-total fertility rate between 2013 and 2018 increased from 0.045 to 0.058 and the relative impact of ART on the TFR increased from 3.1% to 3.4%. Concerning childbearing timing, fertility after ART is significantly shifted towards the age of 39 years when the possibility of the financial contribution of health insurance companies ends in Czechia. The mean age of mothers at childbirth following ART reached 34.5 years in 2018, which was significantly higher than the non-ART mean age at childbirth (30.0 years). The difference in the ART and non-ART mean age at childbirth increased from less than 4 years in 2013 to 4.6 years in 2018. Therefore, the increase in ART usage is, on the one hand, a consequence of the fertility postponement process, but on the other hand, ART can be seen also as one of the “drivers” of fertility postponement. Limitations, reasons for caution Information on the use of ART was estimated based on information on ART cycles performed in Czechia; women who underwent ART abroad were classified as non-ART. Given that Czechia is more likely to be a destination country for cross-border reproductive care, we did not anticipate significant bias in the results. Wider implications of the findings The contribution of the increasing use of ART to the ongoing childbearing postponement process remains significant. Trial registration number not applicable