~25 between ages 20 to 30: <10 after age 35 %
||Human Homo sapiens
||George K, Kamath MS. Fertility and age. J Hum Reprod Sci. 2010 Sep3(3):121-3. Introduction, 1st paragraphPubMed ID21234171
||Spandorfer SD, Avrech OM, Colombero LT, Palermo GD, Rosenwaks Z. Effect of parental age on fertilization and pregnancy characteristics in couples treated by intracytoplasmic sperm injection. Hum Reprod. 1998 Feb13(2):334-8.PubMed ID9557833
||"Naturally, there is an age-related decline in fecundity, the decrease usually starting at the age of 32 with a dramatic fall after the age of 37. Spelt differently, the natural monthly fecundity rate which is about 25% between 20 and 30 years of age decreases to below 10% above the age of 35 (primary source)."