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Chapter 1: Background
In this chapter current evidence on parental substance misuse and its effects on infants is summarised. This information provides the background to the study.
Effects of Maternal Substance Misuse on the Pregnancy and the Foetus
Mechanisms by which harm is caused
Substances misused by the mother are present in her circulation and cross the placenta to the foetus in approximately the same concentration as that in the maternal blood stream. The effects on the pregnancy and the baby depend on the particular substance misused, on the presence of multiple substance misuse, on periods of maternal intoxication and withdrawal and on the effects of substance misuse on the mother's general nutrition and health. It is important to be aware that a mother may be unwilling to give an accurate substance misuse history, because of the perceived risks of stigmatisation, and criminal or child protection proceedings.
There are several effects of maternal substance misuse on the pregnancy and foetus and, as described below, the consequence is an unpredictable outcome for the individual infant. Pre-term infants are exposed to substances for a shorter time than are those born at full term. Drug withdrawal is therefore less common in the pre-term infant, reflecting not only a differing degree of central nervous system maturation but also a shorter exposure to the total intake of drugs, although there are other effects of premature birth which are undesirable. Other effects on the pregnancy and foetus include the following.
1. Viability of pregnancy
The consequences for the pregnancy include increased miscarriage and stillbirth rates. Slattery and Morrison (2002) estimated that about 25% of women who misuse multiple substances have a preterm delivery, with cocaine being especially implicated.
2. Socio-economic associations of substance misuse
Hidden Harm (2003) (p10, 30-33) highlights that the infants of substance misusing mothers are frequently exposed to other unfavourable circumstances, which may lead to pregnancy complications e.g. poor health and nutrition, smoking, alcohol misuse, and injury from violence to the mother. The developing foetus is also at added risk from infection from maternal septicaemia secondary to infected injection sites and from the transmission of Hepatitis B, C and HIV, from the mother sharing injecting paraphernalia or from unsafe sexual intercourse.
3. Neonatal Abstinence Syndrome
At birth, with the separation of the foetal and maternal circulations, the baby's supply of misused substances stops abruptly. In the case of opiates such as heroin this may then be followed by signs of withdrawal in the infant. The progress of this withdrawal suggests that it is not a simple pharmacological process, and in addition there may be further effects of substances on the growing brain. There is some evidence to show that higher levels of substance misuse and polydrug use increase the risk and severity of withdrawal (Fulroth et al, 1989). Newborn infants may start to withdraw within 12 hours of birth, but signs may not appear until the second week of life or, occasionally, even later.
The signs of withdrawal are collectively named neonatal abstinence syndrome ( NAS). The signs include fever, irritability, high-pitched cry, disruption of normal sleep pattern, sweating, stiffness, diarrhoea, sneezing, insatiable appetite, weight loss, fast breathing and skin excoriation from constant movements (Finnegan et al, 1975). In a severe case a baby may develop seizures (Herzlinger et al, 1997). In 30% to 80% of cases of infants exposed to opiates in utero, the symptoms are sufficiently severe for the newborn baby to require treatment (van Baar et al, 1989) dependant on the extent of maternal drug use. Untreated there is a 20% risk of infants dying from NAS (Lam et al, 1992).
Maternal methadone treatment has advantages to the foetus over heroin misuse, in that it may stabilise substance misuse, decrease injecting and promote access to appropriate health care. However, it is associated with longer withdrawal, lower birth weight and smaller head circumference in the newborn (Johnson et al, 2003a; Kaltenbach and Finnegan, 1989; Wilson et al, 1981). Heroin may be associated with shorter withdrawal but it cannot be prescribed in pregnancy and therefore its intake cannot be controlled or titrated (as happens with methadone). If injected, the use of heroin increases the risk of maternal thrombosis, and septic and viral complications. Many mothers who enrol in the methadone programme top up with heroin, either by injecting or smoking.
A discussion of the effects of maternal misuse of cocaine and other substances is beyond the scope of the present study, as they do not cause well defined abstinence syndromes. However, although maternal cocaine misuse does not cause withdrawal in the newborn, it may cause significant damage to the developing brain because of its ability to constrict blood vessels (King et al, 1995; Delaney-Black et al, 1996; Napiorkowski et al, 1996).
Many infants with NAS require admission to a neonatal unit ( NNU) for medication, observation and expert medical and nursing care. Recommended treatment for opiate (including heroin) withdrawal is with morphine (Osborn et al, 2002; Greene et al, 2003; Johnson et al, 2003b), although some infants will need additional drugs. The aim of treatment is to moderate the signs of withdrawal, with a gradual controlled reduction in medication. The duration of stay may be several weeks (from 4-10 weeks on average). This frequently causes stress to parents, disrupts family life and places significant demand on NNU services (Kelley, 1992; Kelly et al, 2000).
Continuing and delayed onset NAS
NAS resolves slowly. Some infants will still need medication when discharged home, and are described as having "continuing NAS." Others have no signs initially and then develop NAS. Where this occurs after eight days of age, this is defined as "delayed onset NAS." These continuing or delayed signs are important because irritability, feeding difficulties and failure to sleep place additional burdens on carers. Medication can be helpful but little evidence exists to direct the choice of medication for community use. Phenobarbitol is used by the services in Grampian; its side effects include drowsiness, lethargy, hyperactivity and possible long term behavioural and developmental problems, (The British National Formulary for Children 2005, p247-248). However, these potential side-effects of phenobarbitol, which in practice are seldom troublesome, are outweighed by its benefits in terms of efficacy, ease of administration, lack of 'street' value, and value in treating infants exposed to polydrug use.
4. Visual problems
Poor visual responsiveness has been reported in infants exposed to stimulant drugs (Hansen et al, 1993). Its prevalence is unknown. There can be delayed visual maturation that completely resolves (known medically as Delayed Visual Maturation subtype 1b), however some of the infants in this subgroup will show neurological and developmental problems (Russell-Eggitt et al, 1998).
The consequence of this poor visual responsiveness is that infants with NAS may show impaired "fixing and following". These are developmental skills normally seen in the early weeks of life. The infant fixes his eyes and looks at an object of interest e.g. a face or a bright light. If the object is moved, the infant continues to look at it, following it with his eyes. Reduced social responsiveness may be another manifestation of impaired visual development. Infants will, by about the age of eight weeks make good eye contact and smile in response to an adult's smile. These responses may be impaired in infants with NAS, so that the mother may have to care for an irritable, poorly feeding baby who neither looks at her nor smiles, thus incurring the risk of impaired parent-child attachment. In addition to this lack of visual response there is an increase in squint (another eye problem); Gill et al (2003) found a ten-fold increase in squint in a selected group of infants with NAS. If these findings are confirmed in a total population study, there are important implications for service development.
5. Sudden unexpected death in infancy
Kandall et al (1993) found a three-fold increase in the incidence of Sudden Unexpected Death in Infancy in substance-misusing mothers compared to controls. This complication, although devastating for the families affected, is rare.
6. Child development
Studies of the affects of maternal substance misuse on longer-term child development have produced conflicting results that are difficult to interpret because of the multiplicity of adverse influences, such as child neglect and under-stimulation, to which these children can be exposed (Kaltenbach & Finnegan, 1989).
Generalised developmental delay may present in the first 6-9 months of life, and thereafter appears to improve. Van Baar et al (1989) found that there were no significant differences in motor, cognitive or behaviour developments at 6-18 months age, although early language development was impaired at 24-30 months (van Baar & de Graaf, 1994). Wilson et al (1979) reported that children aged 3-5 years showed impaired cognitive skills. Ornoy et al (2001) studied schoolchildren born to heroin dependent mothers and found an excess of attention deficit disorder with hyperactivity . Impaired language, and deficits in attention control, may also reflect poor parenting skills and under stimulation.
7. Social effects
The social effects of parental substance misuse are extensively described by Barnard and McKeganey (2004). They describe the children in their study as being subject to multiple disadvantages, such as varying parenting capacity dependent on the "status of the substance misuse" (McKegany 2004), poor parental education, poverty, chaotic household routines, child neglect and abuse, confirming numerous previous findings (Ammerman et al, 1999; Famularo et al, 1992; Fraser and Cavanagh, 1991; Jaudes et al, 1995; Murph y et al, 1991). These problems are aggravated as family size increases. Family support is complex when more than one generation misuse substances.
Children of substance misusing parents: The size and the scope of the national problem
There is growing public and professional awareness of the profound effects of parental substance misuse on the wellbeing of Scotland's children. The extent and severity of the problem was recognised in a publication from the Home Office in 2003: "Hidden Harm, The Report of the Inquiry by the Advisory Council on the Misuse of Drugs".
The Scottish Executive's Good Practice Guidance for Working with Children and Families affected by Substance Misuse "Getting our Priorities Right" (2003) emphasised the importance of agencies and individual professionals working together. This guidance document recommended the development of new procedures and practice, allowing sharing of information about parents, in order to support children. "The Scottish Executive Response to " Hidden Harm" published in 2004, describes both the issues and proposed actions concerning parental substance misuse in the Scottish context.
These government guidelines are essential in directing and supporting new interventions in care for children. The published guidance (and this study) focuses primarily on infants of heroin misusing mothers, and includes those who take additional substances such as cocaine, amphetamines, ecstasy, and methadone. Infants of mothers who used cannabis or benzodiazepines alone are usually excluded because of the complex overlap between occasional substance use and problem substance misuse.
Based on three separate data sources, Hidden Harm (2003) estimated that there are between 41,000 and 59,000 children of problem drug users in Scotland. This represents 4-6% of all children in Scotland under the age of 16 years. Many of these children are in alternative care: the report estimated that between 10,000 and 19,000 children in Scotland are living with a problem drug misusing parent i.e. 1-2% of all children under the age of 16 years. Data from the Scottish Drug Misuse Database quoted in Hidden Harm (2003) suggests that among problem drug misusers, 42% of women and at least 16% of men were living with at least one dependent child. These figures are important when planning new health interventions for children. Services need to be structured, delivered with consistency to a large number of children, and included within existing core services. Whilst most children will be living with their mothers (rather than their fathers), others will be in the care of other family members or in foster care, and interventions also need to be directed to these other carers.
NAS in Grampian, 2000-2003
An audit of NAS in Grampian was undertaken in the years 2000 and 2001. This was possible as 83% of all infants born in the Grampian Health Board Area, including all with antenatally identified risk factors, are delivered in the Aberdeen Maternity Hospital. The audit included mothers who either attended the 'drop-in' clinic or were known to other agencies. Only mothers who were using heroin or had been enrolled in a methadone programme were included in the audit. In certain cases where drug misuse was not known at delivery, opiate withdrawal was recognised in the first few days of life. These infants and their mothers were included in the audit. Mothers rarely volunteer their use of recreational drugs and unless urine surveillance was being undertaken because of a known opiate habit, polydrug use (cannabis, benzodiazepines, amphetamines, ecstasy, cocaine and crack cocaine) would not be detected.
In the two-year audit period (2000-2001) all infants with NAS were from the Neonatal Unit referred on discharge to Dr Myerscough at the Royal Aberdeen Children's Hospital. There was a high 'failure to attend' rate for this service, despite flexibility in appointments and extensive efforts by health and social work staff to contact parents to support their attendance. The reasons for non-attendance were not formally evaluated, but comments from parents indicated the following factors:
- geographical (families may live up to 60 miles from the hospital and are badly served by public transport);
- socio-economic problems (lack of money for travel);
- imprisoned;
- drugs related (continuing problem use of drugs);
- child protection problems (neglect);
- child staying with carers other than the parents.
The failure to keep appointments and the effect on the waiting list of having to make repeat appointments meant that infants were often not seen until a few months of age. As a result of these delays signs of withdrawal had often resolved by the time of the visit and the opportunity for intervention and support had been missed.
A number of children never attended the service and little was known of their progress. Given the possibility of continuing NAS and the vulnerability of these children and parents, this was highly unsatisfactory and, in view of the known hazards of NAS, potentially dangerous.
Data were available on all these aspects of the previous service from the audits of 2000 and 2001: these will be compared with results from this study. In the years 2000 and 2001, 35 of 61 and 34 of 58 infants born to substance misusing mothers developed NAS. Continuing and/or delayed onset withdrawal was identified in 7 and 17 of these infants for the years 2000 and 2001 respectively. No attempt was made to differentiate between continuing or delayed withdrawal in these two years.
There was concern that the figures from the earlier audit were an underestimate, with more mildly affected children being missed. Most known infants came from Aberdeen city. National figures (Hay et al, 2001) suggest that substance misuse behaviour in rural areas is similar to that in urban areas, and thus the Grampian figures might have been unrepresentative of the population served.
As shown in Figure 1, the number of NAS infants has increased, and in 2002 and 2003 affected almost 1% of all live births in the Grampian Health Board area. However, in the past, substance misusing mothers were often unrecognised by health professionals and there was a lack of awareness of the existence of NAS (Boer et al, 1994).
Figure 1: Prevalence of NAS
There was an upward trend in the numbers of drug-misusing mothers, which did not quite reach statistical significance (trend X_ = 2.953, df = 1, p = 0.0859). However, the trend for NAS was highly significant (trend X_ = 29.307, df =1, p <0.0001). This is attributed to the increased incidence of NAS associated with polydrug use, which increased in mothers during this period.
Summary
- There are various affects of maternal substance use on the pregnancy and the foetus, including increased risk of miscarriage; visual problems; socio economic associations with substance misuse; and Neonatal Abstinence Syndrome ( NAS).
- In Grampian in 2000 and 2001, 35 of 61 and 34 of 58 infants (one of the 58 was lost to follow up) born to substance misusing mothers developed NAS. Continuing and/or delayed onset withdrawal was identified in 7 and 17 of these infants in 2000 and 2001 respectively.
- Signs of infant withdrawal were not always identified (and therefore untreated) due to a high rate of non-attendance at out-patient appointments. Reasons for this included distance from the hospital, lack of money for transport, child protection problems and continuing parental problem use of drugs.
- The number of NAS infants increased in 2002, and this increase might reflect in part an increase in professionals' awareness of NAS.
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