Late fatherhood - fathering a child later in life
Do men's biological clocks 'tick' too, and are there any risks in becoming an older father?
Whilst the average age of fathering a child is 32, recent figures from the UK's Office for National Statistics show that in 2004 more than 75,000 babies were born to fathers aged 40 and over - more than one in ten of all children born. Further, around 6,489 children a year are born to fathers aged fifty-plus.
According to US-based National Center for Health Statistics, in 2004 about 24 in every 1000 men aged 40 - 44 fathered a child. This is up almost 18% from a decade ago. Meanwhile, only 3 out of every 1,000 men aged 55 and older are fathers to live births.
Whilst the topic of "older fathers" is increasingly making headlines, what is perhaps less well-known is that there can be risks - both physical and mental - associated with fathering offspring later in life.
Recent research revealed that compared to younger dads, fathers in the older age group were more inclined to be less tolerant of their children's physical activities, perceiving them to be more impulsive and overactive. Older dads apparently also show less affection and warmth towards their partner. [Read about this study]
In July 2008, French scientists reported on a study of over 12,200 couples having fertility treatment and said they had found more evidence that men as well as women have biological clocks, and that they start to tick in their mid-30s.
They said that their eveidence suggested that the chance of a successful pregnancy falls when the man is aged over 35, and the chance is significantly lower if he is over 40.
Couples who had sought treatment for infertility at the Eylau Centre for Assisted Reproduction in Paris between January 2002 and December 2006 were the basis for the study. [Read more about this study]
Risk of autism in children born to older dads
A study recently published in the Archives of General Psychiatry concludes that the offspring of older fathers have a significantly increased risk of autism. The team of UK and US researchers said that children born to men over 40 had a six times higher risk than those born to men under 30. They also said the study was further proof men also had "biological clocks".
The mother's age did not appear to influence the chances a child would have autism, although previous studies into this have produced mixed results.
Rare birth disorders, schizophrenia & bipolar
The incidences of certain rare birth disorders, such as Dwarfism, or achondroplasia (a genetic disorder that affects bone growth and is the most common growth-related birth defect. It occurs in about one in every 25,000 births, affects all races, both males and females and limits their growth to about four feet), are more common amongst births to older fathers. Some of these defects, thought to be new mutations, are only detectable later in life, e.g. schizophrenia.
Researchers at Columbia University College of Physicians and Surgeons found that men aged 50 or over are three times more likely to father a child with schizophrenia compared to men of 25 or under, and men aged between 45 and 49 are twice as likely to have a child with the illness. The researchers estimated that as many as one in four cases of schizophrenia may be caused by the father being old.
The study, published in the Archives of General Psychiatry, looked at records of almost 88,000 people born in Jerusalem between 1964 and 1976, and compared them to data from the Israel Psychiatric Register (part of the Israeli Ministry of Health).
Apert syndrome, which afflicts one in every 70,000 children who are born with fused bones in their heads, hands, and feet, is also linked to the father's age. Men in their 50s and 60s are 10 times as likely to carry and pass along the mutation as men under 30.
In a study carried out by the Karolinska Institute in Sweden, it was noted that the older an individual's father, the more likely he or she was to have bipolar disorder. Children of men 55 years and older were 1.37 times more likely to go on to be diagnosed with bipolar disorder than those of men aged 20 to 24. [Read more about this study].
A study published in the March 2005 issue of Epidemiology, revealed that the risk of preterm birth increases with paternal age. The authors studied couples and their first children, using nationwide registers in Denmark between 1980 and 1996.
Genetic abnormalities & limb defects
Because of the increased risk of genetic abnormalities in the offspring of older fathers, The American Society for Reproductive Medicine has set an upper age limit of 40 years old for semen donors, whilst UK fertility clinics only accept sperm donations from men aged 39 and under.
Research published in November 2005, reveals that men aged 50 and above were more than four times more likely to have a child with Down syndrome and that older men are more likely to have babies with a variety of limb defects. Epidemiologist, Dr Jorn Olsen and his team from the University of California, Los Angeles, used the Danish Fertility Database, which holds information on 70,000 couples and their first born child, to look for differences in children with older fathers.
The finding caused concern among some fertility specialists, who saw the age of sperm donors increase with the government's abolition of sperm donor anonymity earlier this year. "With the change in the law, donors tend to be men who have already had their families," said Allan Pacey, a fertility expert at Sheffield University.
"But about a third of all births in the UK are from men who are older than 35 and, frankly, that's not the best sperm to use in fertility treatment. You want sperm from young, healthy guys that hasn't had time to build up defects."
Dr Olsen reported to New Scientist magazine that whilst the medical risks of starting families older are smaller for older fathers than for women approaching the menopause, the trend of couples starting families later in life means the issue of male age should be taken into consideration.
Research shows that old fathers are three times more likely to take regular responsibility for a
Jack O'Sullivan, Fathers Direct
Sperm quality deteriorates
A study published in June 2006 by Dr Andrew Wyrobek, of the Lawrence Livermore National Laboratory in Livermore, California, found that the genetic quality of sperm deteriorates as a man gets older, becoming steadily more fragmented the older a man gets. DNA fragmentation is associated with greater infertility and a reduction in the chance of conceiving.
Each successive fragmentation introduces a slight risk of error in the genetic material of the new sperm, and this is then passed on to the child. These mutations are tiny and difficult to spot without knowing what mutations to look for. Abnormalities in women's eggs can be picked up more easily, as almost all divisions in a woman's eggs occur before she is born.
Dr Brenda Eskenazi, a co-author of the report, said: "Our research suggests that men, too, have a biological time clock - only it is different. Men seem to have a gradual, rather than an abrupt change in fertility and in the potential ability to produce viable, healthy offspring."
The study included at least 15 men from each age decade spanning 20 to 60 years, and 25 aged 60 to 80. Smokers and men who had fertility problems, or a history of cancer were excluded.
Higher risk of miscarriage
Research published in August 2006 suggests that women who become pregnant by older men are at far greater risk of having a miscarriage. The researchers, from the Columbia University School of Public Health in New York and led by Dr. Karine Kleinhaus, noted that the risk of miscarriage appeared to rise along with the father's age, regardless of how old the mother was. Even after a range of other risk factors which contribute to miscarriage were taken into account, such as smoking during pregnancy and maternal diabetes, the risk was still higher.
The study's authors analysed data from a survey of nearly 14,000 pregnant women undertaken in Jerusalem between 1964 and 1976. 1,500 of those women suffered miscarriages, whilst 12,000 carried their babies to term. The findings were reported in the Journal of Obstetrics & Gynecology.
The risk of losing a baby was 60 per cent higher when the father was aged 40 or over, compared to when he was 25 to 29 years old. It was also about three times greater when the man was aged between 35 and 39 years of age, than if he were younger than 25.
Dr Kleinhaus commented, "As child-bearing is increasingly delayed in Western societies, this study provides important information for people who are planning their families." However, researchers pointed out that despite this generally higher miscarriage rate, older paternal age may only slightly raise the risk to any one couple.
Longer to conceive
A study reported on in July 2000 in Human Reproduction and based on research carried out by teams at Bristol and Brunel universities in the UK, discovered that the older a man is the longer it may take his partner to conceive, regardless of her age. Women with partners five or more years older have less chance of conceiving within a year of trying than those whose partners are the same age, or younger. The odds of conceiving within 6 months of trying decrease by 2% for every year that the man is older than 24 years, and for conception within a year decrease by 3% for each year.
Lower Apgar score
A study published in the July 2006 issue of Epidemiology indicates that new fathers in their 40s and 50s are slightly more likely to have an infant with a low Apgar score than fathers in their 20s. The Apgar score, which was first created in 1952, rates the newborn on five parameters: respiratory effort, heart rate, reflex irritability, muscle tone, and skin color with a value of 0 to 2 (worst to best) for each. Thus, a total score of 10 is optimal. The score is calculated at 1 and 5 minutes after birth.
Statistics on older fathers
Since 1980, there has been about a 40 per cent increase in the number of men between 35 and 50 fathering children and a 20 per cent decrease in the number of fathers under 30. Data from the UK's Office For National Statistics (ONS) reveals that in 1971 the mean age of a father at birth was 27.2 years, but by 1999 this had risen to 30.1. Statistics from 1997 show that whilst the majority of fathers (151,162) were in the 30-34 age group, there were 41,459 fathers aged 40 to 65+ years.
Average age of fathers in Australia now 32.9 years
Australian fathers were an average of 32.9 years old - 2.8 years older than dads with newborns in 1985.
Labels: Late fatherhood - fathering a child later in life