by Jan Friberg M.D., Ph.D.
Although the baby acquires half of the genes from the father, the father’s preconceptual health has often been considered secondary to the mother who is more intimately involved in conception, pregnancy, and delivery. This is further emphasized when it has become apparent that the medical health of the father is reflected into the sperm developmental process, that started approximately 90 days before the fertilizing sperm was ejaculated. There is a close association between the father’s health and semen quality, time to achieve a conception, pregnancy loss, and preterm birth. In addition, paternal health and disease is involved in maternal development of the pre-eclampsia, pregnancy induced hypertension, and gestational diabetes.
Several demographic shifts in the population has occurred into the last few generations that may account for the changes in the preconceptual health of the father to be. Cardiovascular health has also declined in both men and women, obesity numbers have increased, and general health has declined. In addition, parental age has continued to increase. Over the past 40 years the average father has become 3 1/2 years older in the United States. Today, approximately 1% of all births in the United States are created by fathers older than 50 years. Increased paternal age has also been associated with a higher frequency of schizophrenia, autism, ADHD, and rare birth defects
An abnormal sperm analysis may also be a risk factor for future health problems. A well-known fact is that men with infertility have a higher risk for testicular cancer. The etiologic link between impaired spermatogenesis and intratesticular germ cell cancers may be understandable. There is also a dose response relating so that men with worse semen quality also have the highest cancer risks.
The documented association between poor sperm quality and prostatic cancer, lymphoma, and breast cancer is harder to understand
A recently published and well vetted article from Stanford University illustrates the importance to drug exposure to sperm before ejaculation while the sperm are developing in the testis. Over a million Danish deliveries over a 20-year period were studied covering from 3 months before conception to after birth and 3.3% had one or more major birth defects. The mean age of mother and father were 30- and 33-years babies born to mothers who had hypertension or diabetes were excluded. It was found that 5.3% or 145 babies born to fathers who used Metformin within 3 months before conception had birth defects. Of the birth defects genital malformation were the most common and only seen in boys. Insulin and non-exposed siblings were not affected and fathers who took Metformin before or after sperm development were not at risk to have boys with birth defects. It is not clear how Metformin could be involved in creating birth defects, but the drug has created reproductive damage on testing in mice. Since Metformin is widely used for many indications corroboration of the studies is urgently needed.
When we think about reproductive risks we usually automatically think of the risk to the baby while carried by the mother so the types of studies discussed here makes us more aware of the paternal factor that can make a difference in the baby’s development.