Age and infertility
Effect of women's age on Unexplained Infertility:
With the advancing age of a woman, the egg quality and reserve declines. This is seen particularly after the age of 35 - 37 years. Due to a decline in egg quality, there is an increase in the aneuploidy (presence of an abnormal number of chromosomes in a cell) in the embryos. Chromosomal abnormality in the embryo leads to failure of implantation and an increase in the rate of miscarriage. Hence women over 35 years of age are more likely to have unexplained infertility compared to their younger counterparts.
Those <35 years can also sometimes have a low ovarian reserve. However, the egg quality remains good for them. Hence a young woman (<35 years) with low ovarian retains good fertility (so long they have a regular menstrual cycle).
Effect of men's age on Unexplained Infertility:
Age has an impact on the fertility potential of men as well. Though there is no clear threshold like women, sperm quality is found to decline after 40-45 years of age.
However, unlike women, men do not become infertile with age, as sperm production continues throughout life and it is possible to father a biological child at any age for men. However, it might take longer to achieve a pregnancy (even if the female partner is younger). In addition, the increased age of the male partner poses a greater risk to the fertility, pregnancy and the child with increased risk of miscarriages, birth defects, pregnancy complications like pre-eclampsia, preterm birth and stillbirth and increased risk of schizophrenia, autism in children.