The
use of psychoactive drugs is common in Ireland,
however, accurate estimates of prevalence
rates during pregnancy are hindered by issues
such as guilt and denial by the drug user
and prejudice and stigma by society, all of
which can act as barriers to a comprehensive
assessment of a pregnant woman and her effective
engagement with addiction and obstetric services.
This applies to a pregnant woman who uses
both legal and illegal drugs. We will highlight
some of the problems associated with drug
use in pregnancy, focusing on opiates, stimulants,
and benzodiazepines, and offer some guidelines
to best practice.
At
present in Ireland, according to the most
recent National Advisory Committee on Drugs
(NACD) population survey, the estimated lifetime
prevalence rates for any illegal drug is 18.5
per cent (see Table 1 for details).
Much
higher rates are found for alcohol and tobacco
use, both of which have well documented harmful
effects on the developing foetus, neonate,
and child. The European Monitoring Centre
for Drugs and Drug Addiction (EMCDDA) 2002
estimated that about 5.7/1,000 of the population
aged between 15 and 64 engage in “problem
drug use”, which they define as injecting
drug use or long duration use of opiates,
cocaine, and/or amphetamines.
Ireland
has one of the youngest treated populations
of opiate abusers in Europe. In the Dublin
area, prevalence rates in the 15-to-24 age
groups are estimated to be as high as 32/1,000
for males and 17/1,000 for females. This study
also showed that while prevalence rates for
males in general decreased compared to earlier
studies, the number of female opiate users
increased significantly across all age bands.
More of a concern is the evidence to suggest
that the number of young female injectors
may be increasing.
While
examing this study, keep in mind that population
surveys tend to miss marginalised groups such
as the homeless and travellers, it is likely
that these figures underestimate the problem
of drug abuse in pregnancy. The central treatment
list is a register of all people prescribed
methadone in the Irish republic. As of January
2006, there were 7,933 on this list; 2,450
of these were women (30.9 per cent), the majority
of whom are of childbearing age. In 2005,
193 infants were born in the three Dublin
maternity hospitals to women on methadone
treatment.
Pregnancy
is a potential time of anxiety for any woman,
as relationship, financial, and housing issues
become more prominent; some can be snowed
under by an unexpected pregnancy. Drug-taking
women, especially those using heroin, may
have menstrual irregularities, and early pregnancy
signs and symptoms may be misinterpreted as
withdrawals. It is not unusual for pregnancy
to cause a female drug user to seek treatment
for the first time.
Psychological
dependence on drugs usually leads to the prioritising
of drugs over other needs and limited finances
are often by necessity supplemented by crime
and/or sex-work, both of which pose further
risk to the pregnant drug user. If using intravenously
and in an unsafe manner, the woman puts herself
at risk of blood-borne viral diseases. Maternal
infection, poor self-care, malnutrition, and
smoking all contribute to the observed low
birth weights, pre-term delivery, and the
poor nutritional status associated with babies
born to drug users.
Though
some studies have identified evidence of irreversible
chromosome damage in foetuses exposed to drugs,
so far there is only evidence of teratogenicity
specifically related to benzodiazepines and
cocaine, and not opioids. There is, however,
strong evidence that exposure to heroin directly
causes foetal growth retardation and low birth
weight; drugs in general can contribute to
preterm delivery, stillbirth, and sudden infant
death syndrome and neonatal abstinence syndromes.
Harm can be due to the direct effects of drugs,
maternal infection, malnutrition, poor self-care,
and smoking, all of which are made worse by
inadequate antenatal care; these women often
present late, if at all, to the obstetric
services, and for various reasons, may not
engage adequately engage with their antenatal
care.
Opiates
Heroin
use in pregnancy may lead to low birth weights,
premature delivery, stillbirth, and neonatal
death. Ideally, when an opiate-dependant woman
becomes pregnant, she should abstain from
further opiate use. However, many cannot do
this fully due to the nature of addiction.
So, they should be prioritised into substitution
treatment, where the first step is a comprehensive
assessment (see Box 1).
Even
in treatment continued heroin use can occur,
creating fluctuating blood opiate levels as
the patient cycles between intoxication and
withdrawal; these erratic blood opiate levels
similarly effects the developing foetus leading
to foetal distress. If the patient is using
intravenously, she and her baby are at risk
to the effects of blood-borne diseases, septicaemia,
blood clots, and abscesses.
Many
women request detoxification when they discover
they are pregnant, but this is often not practical
due the risks this poses to the foetus, and
the likelihood of relapse. The ability of
methadone to promote stability is well documented
at this stage. In Ireland, in light of this
evidence, methadone is the main substitute
medication used for the treatment of opiate
dependence. The outcomes for the mother and
her infant are better if she is stable on
methadone. If the pregnant women opts for
detoxification, this is usually done relatively
safely in the second trimester, as miscarriage
is a risk in the first trimester, and premature/stillbirth
delivery in the third trimester.
After
delivery, between 48-to-94 per cent of neonates
exposed to opioids during pregnancy develop
signs of withdrawal. This neonatal abstinence
syndrome (NAS) usually begins in the first
24-to-72 hours, but with methadone, can begin
later and last longer.
The
signs of this include: high-pitched cry; rapid
breathing; hungry but ineffective sucking;
excessive wakefulness; tremor; vomiting and
diarrhoea; hypertonicity; sweating; and rarely,
seizures. When these occur, how long they
last, and how severe they become depend on
many factors including: the type of drug(s)
used; the amounts used; when taken in relation
to delivery; and the condition of the infant
after birth. While research carried out in
our own service indicated that higher maternal
methadone dose is associated with an increased
risk of NAS, debate about this exists in the
literature.
The
balance of evidence suggests that the benefits
of substitution outweigh the risk of NAS.
As pregnancy advances, many pregnant women
may require higher doses of methadone to maintain
stability because of weight gain and physiological
changes associated with pregnancy. In some
select cases were the patient is well motivated,
supported, and stable, the option of dividing
the daily dose is a possibility, but for practical
reasons related to service delivery, this
is often not possible. The most important
treatment issue is the promotion of stability
of drug use and lifestyle, and many methadone-maintained
pregnant women can refrain from heroin use
when provided an appropriate methadone dose,
psychological, social, and medical support.
However, if poly-substance misuse persists,
methadone dose may have to be reduced for
safety reasons. In very recent times in Ireland,
buprenorphine, a partial opiate receptor agonist
is being used as a substitution/detoxification
medication, but it is not yet licensed in
Ireland for use in pregnant women. There is
accumulating evidence that infants borne to
women on buprenorphine may be at a lower risk
of NAS and this option will exist in the future.
Stimulant
use
Amphetamine
use has been a problem in Ireland for many
years, but cocaine use has become much more
common in recent years (see Table 1). Cocaine
use in pregnancy is associated with premature
birth, foetal growth retardation, low birth
weight, and smaller head circumference. Stillbirth
rates and congenital defects may also be increased.
Though teratogenic evidence is preliminary
and inconsistent, mothers should still be
advised that cocaine may increase the risk
of congenital malformations. The neonate does
experience difficulties when cocaine is used
near term such as irritability, hypertonia,
and sleep/appetite disturbance. These effects
only last a few days, and generally do not
require treatment; these are thought to be
due to direct toxic effects of cocaine rather
than reflecting withdrawal. The use of cocaine
and heroin in pregnancy has been reported
to increase the risk of NAS. Unlike for people
using opioids, there is no substitution medication
for stimulants. The only option for the pregnant
user is abstinence; cognitive-behavioural
therapy and motivational enhancement therapy
have been shown to be able to promote and
maintain this.
Benzodiazepines
The
use of sedatives in pregnancy is an under-studied
area. However, there is evidence to suggest
that their use in pregnancy, especially in
higher doses, is associated with low birth
weight and cleft lip/palate. Use of these
near term can lead to the “floppy baby syndrome”’
and benzodiazepine withdrawal in the neonate.
Because of the longer half-life of these drugs,
onset of withdrawal can be delayed and duration
prolonged. This can often complicate the problem
of opioid withdrawal and, in addition, sedatives
are more likely to cause respiratory depression
and seizures. The combined use of opiates
and sedatives is particularly dangerous for
both the expectant mother and her infant.
There are places in the two Dublin drug detoxification
units specifically for people in need of stabilisation,
and these pregnant women are encouraged to
avail of these. In some circumstances, therapeutic
doses of benzodiazepines may be prescribed
to discourage illicit use.
Treating-doctors
and society have a duty of care to the pregnant
substance misusing woman and her infant. This
is best done with a multidisciplinary team
approach that liaises effectively with the
obstetric services.
Throughout
this process it must be remembered that most
pregnant women remain stable in their drug
use and, as mothers, can care adequately for
their children, especially if offered non-
judgemental support.
Dr
John Fagan is a Research Registrar and Dr
Eamonn Keenan a Clinical Director in the HSE
Dublin/Mid-Leinster Addiction Services |
