Delayed transitions to adulthood and assisted reproduction: A study of educational differences in Spain.

Transitions to adulthood are increasingly delayed in low-fertility countries, particularly among highly educated women, with significant implications for the timing of attempts to conceive and parenthood. Delayed childbearing increases the risk of infertility and the reliance on assisted reproductive technologies (ART). Spain has experienced pronounced delays in transitions to adulthood alongside a substantial rise in ART use over recent decades. This research adopts a life course approach to examine the association between delayed transitions to adulthood, the likelihood of using ART, and the chances of achieving a live birth following ART, accounting for variations by age and educational attainment. Based on a sample of 12,930 women aged 24-55 from the 2018 Spanish Fertility Survey (SFS 2018), event-history analyses reveal that late first stable employment is associated with a lower likelihood of using ART, particularly for women without university education. Conversely, late housing independence and late coresidential partnership - up to the mid-30s - are linked to a higher likelihood of using ART. Among ART users, the likelihood of achieving a live birth decreases markedly with age, but declines less sharply for university-educated women. The timing of transitions to adulthood and the likelihood of achieving a live birth after ART are not related, except among women who left the parental home or entered a partnership particularly late, who are less likely to succeed. Overall, the findings suggest that ART offers limited capacity to mitigate the effects of delayed transitions to adulthood and fertility, especially for less educated women.