Low Birth Weight and Preterm
Multiple Births.
Over the past two
decades, there has been a dramatic rise in the number of multiple births in
Canada. Between 1994 and 2003, the rate of multiples (per 100 total births)
increased 35%. The recent increase has a significant impact on perinatal
health. Although multiples represent only 1 in 34 births, they account for 1 in
5 preterm births, 1 in 4 low birth weight births and 1 in 3.5 very low birth
weight births. Families with twins or higher order multiples have special needs
that are not always fully understood or appreciated. While babies are a special
gift to a family, with multiples there is a greater risk of immediate and
long-term health risks, plus substantial social, emotional and other
consequences for the family. Compared to single born babies, multiple birth
infants are at greater risk of suffering from long term disability,
particularly cerebral palsy and of dying during the first year. Even when the
babies are healthy, many parents experience overwhelming challenges in caring
for, feeding and transporting two, three or more infants. As multiple birth
children grow, they are also more likely to experience slower language
development, behavioural disorders, challenges in school, and relationship
difficulties. It is possible to reduce the risks and associated costs, and to
improve health outcomes and the functioning of families by linking multiple
birth families to a range of appropriate supports and services.
FREQUENCY OF MULTIPLE
BIRTHS
• There are about 120,000
multiple birth children in Canada under the age of 13 and 48,000 multiple birth
children age 5 and under.
• Each year there are
close to 10,000 twin babies and 400 higher order multiple birth babies born in
Canada.
• Approximately 41% of
multiple birth children born in Canada live in the province of Ontario.
TYPES OF MULTIPLES
There are two types of multiples: monozygotic and
dizygotic. Although the expressions “identical” and “fraternal” are commonly
used by the media and general population, experts and parents of multiples consider
these terms to be inaccurate labels that can have a negative impact on the
multiples. For instance, using the term identical to describe monozygotic (MZ)
multiples causes confusion. Although genetically identical, no two children are
the same. Parents distinguish between their MZ babies by identifying their
differences, and strive to foster their children’s individuality. Similarly,
the term fraternal means a close brotherly relationship, and therefore does not
describe boy/girl or all girl dizygotic (DZ) multiples.
• MONOZYGOTIC
(MZ) multiples result from the
splitting of a fertilized egg during the first two weeks after conception.
Monozygotic twins have the same genetic makeup and therefore are of the same
sex.
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• DIZYGOTIC (DZ) twins resulting from the
fertilization of two different eggs.They can be either the same or of different
sex, and genetically they are no more alike than any siblings.
• TRIZYGOTIC (TZ) – Triplets resulting from three
fertilized eggs. No more genetically alike than singleton siblings.
• QUADRAZYGOTIC (QZ) – Quadruplets resulting from
four fertilized eggs. No more genetically alike than singleton siblings.
• HIGHER ORDER MULTIPLE
BIRTHS is the term used for births involving three or more babies (e.g.
triplets, quadruplets, quintuplets). There can be many variations of zygosity
within a higher order multiple set. For example, a set of quintuplets can
consist of two MZ (monozygotic) children and three TZ (trizygotic) children
resulting from four fertilized eggs.
INFLUENCING FACTORS
The odds of having
multiples are influenced by many factors, and multiple birth rates have changed
throughout the years due to some of those factors. The widespread use of
fertility drugs and high-tech procedures such as in vitro fertilization (IVF),
and increased maternal age are considered to be the major contributing factors
to the increase in multiple births.
Multiple
Births by Maternal Age
• Multiple births are
more frequent among women in their thirties and forties. In 2002, approximately
55% of multiple birth babies were born to women age 30 and older. Infertility
Treatments
• Approximately 35% of
multiple pregnancies result from infertility treatments (fertility drugs and/or
reproductive technologies). However, it is estimated that over 80% of higher
order multiples result from these treatments.
• The incidence of
monozygotic multiples is doubled in multiples conceived through the use of
ovulation stimulation treatments.
Maternal
Weight
• Women with a
pre-pregnancy Body Mass Index (BMI) of 30 or greater are at a significantly
increased risk of conceiving dizygotic multiples.
THE
IMPACT OF MULTIPLE BIRTHS
Multiple birth infants
have a disproportionately high risk of preterm birth, perinatal death and
illness which places enormous stress on families as well as health, social and
education services.
Maternal
Health
• Multiple pregnancies
present significant complications for pregnant women, such as gestational
hypertension, preeclampsia, anemia, gestational diabetes, premature rupture of
membranes, and postpartum hemorrhage.
• Reduced activity,
withdrawal from employment, and prescribed bed rest (at home or hospital)
during pregnancy are common for expectant mothers of multiples. Prolonged bed
rest can lead to cardiac and/or respiratory problems and muscular wasting, and
recovery from these problems may take several weeks.
• Cesarean section is
needed for over 50% of twin pregnancies, and is almost always required for
higher order multiples.
Since infection,
prolonged pain, and delayed recovery are more common with caesarean deliveries,
new mothers of multiples frequently have difficulty in holding, carrying and
caring for their infants.
Problems
Unique to Multiple Pregnancy
• Monozygotic multiples
who share one placenta (monochorionic) have a high incidence of umbilical cord entanglement,
Twin-to-Twin Transfusion Syndrome (TTTS)* and fetal death.
* TTTS is a condition in
which blood from one monozygotic twin fetus transfuses into the other fetus via
blood vessels i the placenta. TTTS can also occur between monozygotic multiples
in a triplet or more pregnancy.
• Poor and differing
fetal growth between the babies is common. Perinatal Death
• Occasionally one fetus
dies in early pregnancy and is reabsorbed (Vanishing Twin Syndrome).
• Compared to mothers
expecting a single baby, mothers expecting multiples are nearly three times
more likely to lose one, more or all of their babies before birth.
Preterm
Birth
• The average length of
pregnancy is 36 weeks for twins, 33 weeks for triplets, 31 weeks for
quadruplets, and 29 weeks for quintuplets.
• Most multiple birth
babies are born before full term (40 weeks), and 57% of twins and 98% of higher
order multiples are born preterm (before 37 weeks).
• Multiple births are the
fastest growing segment of the preterm birth infant population,
representing 20% of all
preterm births.
• Due to their
prematurity, multiple birth infants frequently have ongoing health problems
such as respiratory and neuro-developmental challenges, requiring prolonged and
frequent hospitalization.
Infant
Death
• Infant death is 4 to 5
times more likely to occur among multiple births than among singleton births.
• Multiple birth babies
are more vulnerable to Sudden Infant Death Syndrome (SIDS).
Low Birth
Weight
• Low birth weight
(<2500 grams, or 5.5 lbs) and very low birth weight (<1500 grams, or 3.3 lbs)
occur about nine times more frequently among multiple than singleton births.
• Multiples represent
about 25% of all low birth weight infants and 28% of the very low birth weight infant
population.
• The average birth
weight for each multiple birth baby is approximately:
– Twins 2,500 grams
(5-l/2 pounds)
– Triplets 1,800 grams
(4 pounds)
– Quadruplets 1,400
grams (3 pounds)
• Given that multiple
birth infants are more likely to be born with a low birth weight, they often
have short and long term health and developmental problems, require more
feedings during the early weeks or months, and tend to require more care.
Disabilities
• Complications during
pregnancy, delivery and in the early weeks of life may result in one, more or
all of the babies having special needs.
• Compared to
singletons, twins are 1.4 times more likely to have a disability. Similarly,
triplets are 3 times more likely to have a severe disability and 1.7 times more
likely to have a moderate disability.
• Multiples are at a
significantly increased risk of having Cerebral Palsy (CP). In contrast with
single born children, twins are 10 times more likely, triplets 30 times more
likely, and quadruplets 110 times more likely to have CP.
• Since disabilities
and/or developmental delays are more common in multiples, parents often must
commit to intensive and ongoing involvement in therapies throughout the first
few years.
Psychosocial
and Financial Issues
• Since death is much
higher among multiple births than singletons, parents who lose one, more or all
of their babies face extremely difficult situations. In the case of losing all
of the babies, the parents have lost not only their babies but a unique
parenting experience. If there are survivors, the parents find it hard to
celebrate the birth and the anguish of death at the same time. As a result, some
parents find it difficult to attach emotionally with the survivor(s). For those
who have experienced years of infertility, the loss of one or more of the
babies can be particularly heartbreaking.
These
additional issues can make the grieving process more complex.
• Some centres that offer
assisted conception, also offer Multifetal Pegnancy Reduction as an option to
women who conceive higher order multiple pregnancies. Multifetal Pregnancy
Reduction aims to increase a woman’s chance of a near term delivery of a
singleton baby or twins instead of three or more babies.This procedure and
associated decisions are not straight forward and the long term psychological
effects may be profound. In particular, the decision whether or not to undergo
this procedure can be extremely distressing. For many, after experiencing the
emotional and financial strains of infertility, the decision to reduce seems to
be in conflict with the goal of conception.
• The total cost of
raising multiples is higher than the cost of raising the same number of
singletons. Parents must purchase clothing and equipment all at once (e.g.
cribs, special stroller, car seats, high chairs, etc.), preventing an opportunity
to pass along hand-me-downs. The first year “start up” cost for basic
essentials of infants for families with triplets is approximately $12,000
higher than families raising a single baby. This amount does not include: the
cost of disposable diapers; transportation needs when a larger vehicle is
required to accommodate three, four or more infant car seats; the cost of
moving to larger accommodation or renovations to existing accommodation;
childcare costs; or the loss of a second family income if the mother does not
return to the paid labour force.
• Caring for multiples is
more difficult and physically demanding than caring for one child, especially
during infancy and childhood, and with higher order multiples. One Australian
study showed that mothers of triplets spend an average of 197.5 hours per week
(unfortunately there are only 168 hours in a week) between themselves and
paid/volunteer assistance, on caring for their babies and managing the
household. This situation can place extraordinary stress on the couple
relationship.
• Parenting multiples
presents unique situations and experiences yet information, support and advice
regarding multiple births is often difficult to find.
• Compared to a single
baby, the maternal and paternal attachment process takes longer and is more
complex with two, three or more babies.
• Since most new
mothers of multiples suffer from sleep deprivation and chronic fatigue, they
are at higher risk of Post-partum Depression (PPD) than mothers of singletons.
• Parents of multiples
are at risk of maternal isolation, marital stress, financial difficulties and
illness. This stress, in combination with the lack of access to special
information and support, places multiple birth families at an increased risk of
family problems.
• As a result of the
unrelenting parental demands, the associated fatigue, and the attention that
multiple birth babies attract, the birth of twins, triplets or more can have a
negative impact on other children in the family (e.g. behavioural changes).
• Due to the
extraordinary parental stress, multiple birth infants are at a greater risk of
abuse such as Shaken Baby Syndrome.
PREVENTION
In order to avoid short
and long term problems, families with multiple birth children require timely access
to preventative health care and social support that is specifically designed
for parents of multiples.
• Physicians need to inform families who seek
infertility treatments, about the known risks of multiple pregnancy,
multi-fetal reduction, and parenting demands before starting therapy.
• Physicians need to refer patients to appropriate
specialists for infertility management and high-risk multiple gestations.
• To ensure that the pregnancy goes as near to term
as possible, women expecting multiples require:
– Early
diagnosis of the multiple pregnancy (before 16 weeks) in order to :
• Identify monozygotic multiples sharing a single
placenta (monochorionic)
• Put into place an appropriate obstetrical care
management plan
• Allow the mother and her family adequate time to
adjust
– Early nutritional counselling and dietary
resources to support a weight gain of 18-27 kilos (40-60 pound)
– Education regarding
preterm labour
– Obstetrical care
which follows the protocols of best practice for multiple birth
• Multiple birth
families need to receive special support. In particular:
– The primary antenatal
care provider should identify all those involved in the care of the family and
ensure that close links
are sustained throughout the pregnancy and postpartum period;
– Early prenatal
classes designed for parents expecting multiples;
– Practical help and
referral to local resources;
– Multiples-specific
breastfeeding support.
– Links with other
parents who share their unique experience (e.g. Multiple Births Canada, local parents
of multiples support group).
– When the health of
the mother or family circumstances indicates, limited activity, greater work restrictions
and increased bed rest are often recommended. In these situations, mothers may
also require in-home nursing support and household help, especially if there are
older siblings.
• Creation of healthy
public policies must recognize the need for and benefits of additional supports
for multiple birth families. Programming must address barriers to supports and
services for multiple birth families including lack of services, long waiting
lists for services, and the need for service coordination.
