Abstract
Study question
Is reproductive success measured as CLBR per inseminated oocyte, per embryo transfer and per embryo transferred affected by paternal age in autologous IVF-ICSI cycles?
Summary answer
The number of embryo transfers and embryos transferred until live birth, but not the number of inseminated oocytes, were significantly different among the age groups.
What is known already
In recent years, there has been an increase of the average paternal age at which the first child is conceived. Therefore, there is a growing interest on the study of the impact of male age on the reproductive outcomes in assisted reproduction cycles (ART). Several studies have shown negative effects of advanced paternal age on semen parameters, embryo aneuploidy, miscarriage, male infertility,.... However, other studies have found no association between them. Hence, the impact of paternal age on reproductive outcomes still remains uncertain, leading to a need of more research on this topic, which this study tries to address.
Study design, size, duration
This retrospective observational multicentric cohort study has included autologous IVF-ICSI treatments (n = 6295) performed to couples with etiology of male infertility (non-normozoospermic) in Spain IVIRMA clinics between January 2008 and March 2020 using patients’ own sperm sample. Paternal age ranged from 20 to 75 years. The study population was categorized in 5 groups following the criterion of homogenizing the number of observations between groups: 20–34 (A), 34–37 (B), 37–39 (C), 39–42 (D) and 42–75 (E) years.
Participants/materials, setting, methods
Considering that male age could be a factor affecting reproductive outcomes, we evaluated men with different age that performed an autologous IVF-ICSI treatment with their own semen, etiology of male infertility and known age. Data was exported in order to obtain the clinical database and Kaplan-Meier was used for data analysis. P < 0.05 was considered statistically significant. We measured reproductive success by CLBR per embryo transfer, per embryo transferred and per inseminated oocytes until live birth.
Main results and the role of chance
This study considered approximately 2976 patients and 4385 embryo transfers. The CLBR per inseminated oocyte showed no significant difference between the study groups: A (6.43%, 48.24%, 81.38%), B (5.74%, 52.14%, 82.87%), C (6.14%, 49.83%, 83.69%), D (5.89%, 53.60%, 81.16%) and E (6.61%, 47, 52%, 77.85%) for 4, 13 and 21/22 inseminated oocytes, respectively. In terms of CLBR per embryo transfer, the results obtained for each of the age groups were: A (31.81%, 71.89%, 87.63%), B (28.89%, 67.87%, 82.63%), C (27.10%, 68.87%, 88.17%), D (23.45%, 64.63%, 100.00%) and E (22.88%, 55.48%, 63.31%) for 1, 4 and 7 embryo transfers, respectively. There were statistically significant differences in the CLBR per embryo transfer between the studied age groups (p < 0.0001). CLBR per embryo transferred for each age group was as follows: A (10.85%, 60.53%, 80.88%), B (9.34%, 59.75%, 78.23%), C (11.89%, 57.63%, 74.97%), D (10.25%, 52.71%, 77.76%) and E (11.71%, 51.50%, 71.51%) for 1, 4 and 7 embryos transferred, respectively. As in the case before, there were statistically significant differences in the CLBR per embryo transferred between the age groups (p < 0.05). The findings presented highlight that the increase in paternal age could be affecting the reproductive outcomes in IVF-ICSI cycles using autologous oocytes.
Limitations, reasons for caution
The retrospective nature of this study leads to biases derived from the clinical practice and to the presence of missing data (limiting sample size). Moreover, this study considered autologous cycles, therefore the results were not adjusted for female factors.
Wider implications of the findings: Our study showed that reproductive outcomes measured by CLBR per embryo transfer and embryo transferred until live birth were significantly different between the paternal age groups in autologous IVF-ICSI cycles of infertile males. Hence, paternal age could be affecting reproductive outcomes and it should be considered for improving infertility counselling.
Trial registration number
NA
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