To explore the relationship between sperm DNA fragmentation index (DFI) and clinical outcomes of intracytoplasmic sperm injection (ICSI) cycles due to male factors.

We used a retrospective cohort to analyze the clinical data of 387 ICSI cycles in Reproductive Medicine Center of First Affiliated Hospital, Nanjing Medical University from January 2016 to December 2017. All patients were undergoing their first ICSI cycle, using a flexible antagonist protocol. Patients were divided into three groups according to sperm DFI, including group A, DFI≤15% (n=167), group B, 15%<DFI<30% (n=145) and group C, DFI≥30% (n=75). Laboratory and clinical outcomes were compared among the three groups.

There were no significant differences in maternal age, body mass index (BMI), anti-Müllerian hormone (AMH), follicle-stimulating hormone (FSH) and antral follicle count (AFC) among the three groups (P>0.05).The males in group C [(32.56±5.70) years] were older than those in group A and group B [(30.27±4.04) years，P=0.002； (30.22±4.81) years， P=0.003]. The fertilization rate (86.7%) and the rate of transplantable embryos (88.3%) in group A were significantly increased compared with group B (83.8%, P=0.024 5; 84.9%, P=0.012 1) and group C (82.1%, P=0.005 6; 84.4%, P=0.022 7). There was no significant difference in good-quality embryo rate and abortion rate (P>0.05). The cumulative live birth rate was decreased in group C (74.7%) compared with group B (78.6%) and group A (82.0%), but there was no statistical difference (P>0.05).

Sperm DFI is an important indicator for assessing male fertility, it may affect embryonic development and assisted reproductive outcomes. An increase in the age of the man may lead to an increase in DFI. DFI≥30% may reduce the cumulative live birth rate of ICSI, but a larger sample study is still needed.

Sperm DNA fragmentation index; Cumulative live birth rate; Intracytoplasmic sperm injection; Sperm DNA integrity; Fertility rate; Rate of transplantable embryos