Paternal age effect is the relationship between paternal age at conception and biological effects on the child. That can relate to birth weight, congenital disorders, life expectancy and psychological outcomes. A review suggested that while severe health effects are associated with higher paternal age, the total increase in problems caused by paternal age is low. Though growing evidence shows that the offspring of older fathers have reduced fertility and an increased risk of birth defects, such as cancers, and schizophrenia.
Evidence for the paternal age effect has been seen in a number of conditions, diseases and other effects. In many of these, the statistical evidence of association is weak, and may be related by confounding factors and behavioural differences.
Pregnancy effects and Birth outcomes
Several studies have reported that advanced paternal age is associated with an increased risk of miscarriage caused by chromosome abnormalities in the sperm of aging men. An increased risk for stillbirth has also been suggested for pregnancies by men over 45.
A systematic review published in 2010 concluded that the graph of the risk of low birthweight in infants with paternal age is “saucer-shaped” or U-shaped; that is, the highest risks occur at both low and at high paternal ages.Compared with a paternal age of 25–28 years as a reference group, the odds ratio for low birth weight was approximately 1.1 at a paternal age of 20 and approximately 1.2 at a paternal age of 50. There was no association of paternal age effect with preterm births or with small for gestational age births.
Illness associated with paternal age effect
Schizophrenia- It is thought by some to be associated with advanced paternal age but it is not proven.
Cancers- Paternal age effect may be associated with an increased risk of breast cancer,but the association is weak and there are confounding effects.
Down syndrome- It appears that a paternal-age effect might cause an onset to Down syndrome, but it is very small in comparison to the maternal-age effect.
Intelligence- If fathers are younger than 25 and older than 44 tended to have children with lower IQs.
Fertility of the father- A review suggested older men have decreased pregnancy rates, increased time to pregnancy, and increased infertility at a given point in time.
An evaluation of various scenarios may help to determine an optimal time period of fatherhood that balancing the social and economic advantages for the offspring of delayed paternity against the corresponding small, but increasingly well reported, genetic disadvantages. Now-a-days, couples have begun to push the limits of conception to the point that children are commonly born to parents of advanced maternal and paternal age. Possible interventions might include health promotion advising people about the risk of delaying childbearing or changes at a societal level (for example, family benefits, flexible working) that encourage couples to have children earlier rather than later and discourage paternal age effect on pregnancy.