In medical terms the world of assisted conception and fertility treatment is still relatively new. Research is constantly being conducted to further develop assisted reproductive technology (ART).
Consultant pediatrician Dr Elizabeth Bryan is a leading specialist in the field of multiple pregnancies. She established the first clinic for twins in London in 1987 and works closely with families with multiple births. As founder and medical director of the Multiple Births Foundation UK and a co-founder of the Twins and Multiple Births Association, Dr Bryan is the author of more than 50 medical papers and her widely acclaimed book, Twins and Higher Multiple Births.
In medical terms the world of assisted conception and fertility treatment is still relatively new. Research is constantly being conducted to further develop assisted reproductive technology (ART) and to investigate long-term repercussions for both the children and parents concerned.
Figures indicate that as the use of ART increases, so too does the incidence of multiple births, due to the practice of multiple embryo transferral (involving the transferral of 3-10 embryos in one cycle) being routinely carried out in many countries. In the Czech Republic and Greece, more than 70% of IVF cycles still involve three or more embryos being transferred.
The result, an escalating number of higher order multiple births (triplets or more), is a key issue concerning health professionals throughout the world.
There were 3,900 multiple births registered in Australia in 2000, compared to 2,200 in 1980. Of these, 3,800 produced twins while the remaining 100 resulted in triplets or higher births. According to the Australian Bureau of Statistics, the number of twin births has increased by 71% since 1980, and the number of triplet births has increased by 257%.
“The whole IVF scene has escalated,” said Dr Bryan, during an address at Melbourne’s Royal Women’s Hospital.
Dr Bryan was in Australia speaking about the “emerging epidemic of multiple births” and its costs to all involved. Of greatest concern is the increase in triplet births directly related to multiple embryo transferral, she said.
In her presentation titled, “The Cost of Multiple Births – too high a price?” Dr Bryan addressed several key issues. These included the following:
Perinatal Factors
The term “perinatal” refers to the period from the 28th week of gestation to one week following delivery. Medical professionals are deeply interested in the effect that perinatal factors may have on multiple birth babies.
It has been found that many multiple birth babies suffer from intra-uterine growth retardation. In particular, the prevalence of cerebral palsy dramatically rises with triplets, said Dr Bryan. Research shows that those babies exposed to a “stormy” perinatal period are more likely to have cerebral palsy, she said.
In some cases, if one of the multiple birth babies has died during the pregnancy, there exists an increased risk of cerebral palsy in the surviving baby or babies.
It is common for women giving birth to multiples to experience delivery complications, added Dr Bryan. In many hospitals throughout the world, delivery of multiple babies culminates in a Caesarean Section.
Premature Babies
It is known that multiple birth babies are much more likely to be born pre-term, before 40 weeks. Statistics show that many twins are born around 37 weeks, although some are born much more prematurely.
In one study, 62% of twins were born at 36 weeks and beyond, but only 12% of triplets and 7% of quadruplets, were born beyond 36 weeks gestation. Incidentally, multiple pregnancies extending beyond 41 weeks are known to increase the risk of perinatal problems occurring.
Birth Weight
Another concern is the incidence of low birth weight, prevalent in multiple births, said Dr Bryan. Many multiple birth babies are generally born 1000 grams lighter than single born babies. Figures show that 6% of singleton babies weigh less than 2500 grams. This compares with 50% of twins, 90% of triplets, and almost all of higher multiple birth babies (that is quadruplets or more) being born recording birth weights less than 2500 grams.
Furthermore, figures indicate that 0.7% of single born babies fall below 1500 grams in weight, compared to 9% for twins, 28.4% for triplets and 52.3% for quadruplets. Birth weight discordance, where the babies are growing at different rates, is a great concern and often raises an ethical dilemma.
“What do you do for a foetus that is failing to grow? Do you try and save that one, at the same time risking the pre-term complication in the otherwise healthy baby?”
Perinatal Mortality
Of grave concern is the increase in the incidence of perinatal mortality among births resulting from assisted conception, compared to those of non-ART births.
“If you lose one of your babies, you are a deeply grieving family,” said Dr Bryan.
“There are the added complications of caring for surviving children. Celebrating the birth or births of surviving children while mourning the death of another can be a very complex position to be in – and one that some parents cannot cope with. They may even reject the survivors as they grieve the baby that has died,” she said.
Environmental Factors
Families of multiple births inevitably face environmental factors. It has been found that many multiple birth babies suffer learning difficulties and this is particularly prevalent among monozygotic multiple births, said Dr Bryan. Monozygotic multiples occur when one egg is fertilised by one sperm and then splits into two or more. The embryos produced are always the same sex and are identical.
In assessing the causes, Dr Bryan said we must take into account the following:
The Shared Mother-Infant Relationship
“Some mothers, and indeed some fathers, find it very difficult to fall in love with more than one baby at a time,” said Dr Bryan.
Likewise, children of multiple births may have difficulty in relating to their mother and father and find that the shared relationship inhibits them the access to the attention and the stimulation that a normal single child would receive.
At times the competition can be intense and even aggressive, said Dr Bryan.
This may retard development and as a result, many of these children are more likely to have difficulty in communication and language development. This problem is further compounded if one child has a medical condition requiring more attention.
A study involving 200 pairs of twins found that at the age of four years, the average age of development of twins was 3 1/2 years, six months behind that of single children. Language development is an area particularly affected.
Aspects of communicating as a threesome include:
- Reduced eye contact
- Reduced dialogue with the mother – studies have shown that mothers of twins talk less to their children than mothers of single children, partly because they are busier, partly because they tend to think that the children can entertain each other
- Reduced opportunity to learn – often time is short and many expeditions are near impossible with two children
- Furthermore, it has been noted that single children tend to have an adult as a language role model, whereas multiple infants tend to have a constant exposure to each other’s inferior communicative skills, reinforcing errors, she said.
Concentration
Solitude is important for a child to learn to be comfortable in its own company and is important in developing concentration, she said. Twins often lack solitude.
Research has shown that twins are more likely to suffer from attention hyperactivity distraction syndrome, often partly due to perinatal factors, but reinforced by the fact that they rarely have time on their own, she said.
“Some may never have time alone,” said Dr Bryan.
Premature Babies & Mothers
A study in the United States compared premature twins and premature single babies and how their respective mothers behaved towards them. The babies involved in the study were aged 18 months.
The study found that, in general, mothers of twins showed fewer initiative responses, were less responsive to the positive signals of their babies, and were less responsive to their babies crying. These mothers lifted, held, touched, patted and talked less to their twin babies. “This behaviour was predictive of the cognitive development of these children,” said Dr Bryan.
Behavioural Factors
Domination
The problem of domination is common in multiples, particularly boy-girl twins, especially in the pre-school period when the girl tends to be more socially confident and mature, appointing herself spokesperson.
“She will often look after her brother and he may be happy for her to do so. This is not the way to get the esteem of his peers and should not be allowed to continue, she said. Such domination can have far-reaching effects.
Twin girls, Sophie and Lucy, came to the clinic in London and drew pictures of their family. Lucy drew a picture in which she was vastly smaller in proportion that her sister. Lucy clearly did not feel the same size as her sister although she was the same size and they were monozygotic. It was Lucy’s self esteem that was the problem.
Self Esteem
A study carried out involving pre-school twins linked both birth order and birth weight to self-esteem. The first-born child, and the child recording the greater birth weight, displayed more confidence.
The most important factor of all, however, was the order in which the newborn babies were taken home from the hospital. While this may seem surprising, several cases have highlighted this aspect, said Dr Bryan.
“It should be strongly encouraged, where possible, that twin children are taken home together,” says Dr Bryan.
Collusion
Disciplinary problems, in general, are greater for twins than for single children. And for parents, collusion can be one of the biggest concerns.
As Psychologist Dorothy Birlingham said:
“Twins use each other to accomplish what one cannot do alone. They have the strength of two and are invincible”.
They have each other to encourage unruly behaviour and with their combined skill they do not get bored of being naughty, said Dr Bryan. Disciplinary problems are further compounded with triplets and quadruplets.
The Problem of Exclusivity
Children of multiple births get used to being thought of as special due to the “twinship” and later in life they can find it very difficult when they are separated from their twin. “Often part of their own self-image and confidence was due to their ‘specialness’ as twins and they excluded the world because they themselves were exclusive,” said Dr Bryan.
Practical Problems for Families
Adjustment is always tough for any parents welcoming newborns into the family. With multiples, the pressures are often compounded yet help is not always readily at hand. The Australia Multiple Birth Association asked 74 mothers of six-month-old triplets to calculate how many hours it took to look after the babies and do the housework each week. The mothers calculated that it took 197.5 hours – there are only 168 hours in a week.
Furthermore, many mothers of multiples who have undergone fertility treatment are older women and often have less energy. In 1980, there were 730 multiple births to women aged 30 years and over, constituting 1% of all births to women in that age group. By 2000, this number has increased to 2,300, constituting 2% of births in this age group.
Depression
Not surprisingly it’s been found that depression is more common amongst mothers of twins and higher multiple births, said Dr Bryan. A study in the United Kingdom in 1991 concluded that mothers of twins are more likely to experience depression, indicating the additional and exceptional pressures placed upon the mothers’ emotional wellbeing. The children involved in this study were five years old, disclaiming the possibility of postnatal depression, she said.
Sibling Behaviour
Behavioural problems among siblings in families with twins are considerably higher than siblings of single children. Studies have shown a three-fold increase in the behaviour of siblings in the 2-5-year age group. In the older age group, 8-11 years, the effect of the arrival of twins was even more profound with a six-fold increase in behavioural problems.
Child Abuse
Research in Japan showed a higher prevalence of child abuse among multiple births. There was a ten-throw increase amongst multiples, and it tended to be the disadvantaged child, either the smaller or less responsive or disabled child, that was affected. In the rare cases where both twins were affected, serious psychiatric illnesses were usually present, she said.
Positive Factors
While parenting multiples is clearly more demanding, such a life-changing event can have its up side for all involved.
“Clearly there are positive factors,” said Dr Bryan.
Being a child of a multiple birth is certainly a unique existence. Among the many benefits, Dr Bryan cited the bonds of companionship, affection, co-operation, stimulation, encouragement, security, sympathy and empathy.
“I know many adult twins who regard their twin-ship as their greatest bonus in life,” she said.