The Influence of Advanced Paternal Age on Sperm Chromatin Integrity and Early Embryo Morphological Development during ICSI

Abstract

The study determined the impact of advanced male ageing (≥50 years) on sperm chromatin integrity and early embryo morphological development in intra-cytoplasmic sperm injection (ICSI) technique cycles. Six hundred sub-fertile men were age-grouped; X 1 (50 to 59 years), X 2 (60 to 69), and X 3 (≥70), were compared with 600 fertile males of known fertility (Y, age 25-35 years). Oocytes from 254 women, aged ≤ 30 years, were included. Sperm were analyzed using acridine orange fluorescence test (AOT) and categorized: "low", "intermediate" and "high" damage. After ICSI, embryos were evaluated and categorized as "good", "fair" or "poor" quality. Embryonic morphological development was assessed at three stages: fertilization, early and late paternal effect. The AOT results were: X 1 : low = 29, intermediate = 53 and high = 118; X 2 : low = 11, intermediate = 42 and high = 147; X 3 : low = 8, intermediate = 24 and high = 168; Y: Low = 486, intermediate = 71 and high = 43. The fertilization rate was: X 1 , 329/350 (93.7%); X 2 , 298/350 (85.1%); X 3 , 225/350 (64.1%) and, Y, 350/350 (100%). Associations between increasing age and sperm chromatin damage (χ 2 (723.249, 6) p < 0.0001), increasing age and inability to fertilize (χ 2 (210.990, 3) p < 0.0001) were observed. Associated with increasing age was the significant proportion of morphologically poor quality embryos over the five days after fertilization. Male age ≥ 50 years, is highly associated with abnormal sperm chromatin organization, an inability to adequately fertilize with ICSI methodology, an increase in the number of poor quality embryos and, a corresponding decrease in the number of good quality embryos five days after fertilization.