Received March 21, 2025
Accepted November 25, 2025

Objective: Infertility is a major global health issue, with assisted reproductive technologies (ART) commonly employed as a solution. Although numerous factors related to couple characteristics and ART cycles are implicated in pregnancy outcomes, data on infertile couples in Portugal is limited. The Portuguese Northern and Central Regions Infertility Study 2014-2018 (NORCE-INF 14-18) aimed to evaluate how couple characteristics and in vitro fertilization (IVF) cycle parameters affect the success of the first IVF treatment, specifically through cumulative live birth rate (CLBR). Methods: This multicenter, observational, longitudinal, retrospective cohort study gathered data from six public fertility centers in Northern and Central Portugal, involving couples undergoing their first IVF treatment from January 2014 to December 2018, along with subsequent frozen embryo transfers (FET). Results: The analysis included 5,250 couples, with mean female and male ages of 34.3 and 36.1 years, respectively. The average duration of infertility was 45.88 months, predominantly resulting from male factor infertility. Among 3,767 cycles with fresh embryo transfers, the live birth rate was 29.5%. Additionally, the study found a CLBR of 25.5%, leading to 1,601 live births. Logistic regression identified female age as a key predictor of ART success, showing an inverse relationship with pregnancy rates. Conclusions: The NORCE-INF 14-18 study represents the largest analysis of ART outcomes in Portugal, revealing that approximately 26% of couples achieved live births after their first IVF cycle, emphasizing the importance of demographic factors in treatment success.