The terms “substance” and “drug” are used interchangeably. The term “drug” may be used to cover licit substances (tobacco and alcohol) and illicit substances such as central nervous system depressants (opiates and opioids, e.g. heroin and “street” methadone), stimulants (cocaine, crack, amphetamines and ecstasy), volatile substances and cannabis. It includes prescription drugs (such as benzodiazepines) taken in a manner that was not indicated or intended by a medical practitioner, and failing to use over-the-counter preparations such as codeine-based products (e.g. cough medicines, decongestants) in accordance with instructions. A combination of prescribed medications is known as “polypharmacy.” Combinations of substances may result in “polydrug” “misuse,” “harmful use” or “dependence” (or addiction). All may be associated with physical or psychologic co-morbidity [1].

It should be noted that just one dose of a drug can sometimes be fatal and, therefore, any substance “use” must be considered in detail. A working definition of “substance misuse” is the use of substances that is socially, medically or legally unacceptable or that has the potential for harm.

There is great variability in prevalence rates in different countries and regions of countries, and in different ethnic groups [4]. This may be explained in part by differences in definitions, in patterns and modes of use, in screening, assessment and diagnostic tools, the time window during which use is being measured (e.g. lifetime, previous year or previous month usage), measurement techniques, and study settings, as well as by wider environmental influences such as availability, price, social acceptability, seizure and arrest policies.

Alcohol

Alcohol exposure varies from 0.2% to 14.8% depending upon stage of pregnancy, definition of exposure, diagnostic classification and method of assessment. A recent Swedish study reported risky use of alcohol during the first 6 weeks of pregnancy at 15% [10], where risky drinking was defined as drinking more than 70 g/week (see Box 19.2) during any 2 or more weeks and/or two or more episodes of more than 60 g/episode. A Norwegian study demonstrated similar findings: binge drinking was reported in 25% during the first 6 weeks of pregnancy [11]. The behavioral risk factor surveillance system survey in the USA reported that approximately 10% of pregnant women aged 18–44 used alcohol and approximately 2% engaged in binge drinking (five or more drinks on one occasion) or frequent use of alcohol (seven or more drinks per week). It also showed that more than half of the women in this age group who did not use birth control (and therefore might become pregnant) reported alcohol use and 12.4% reported binge drinking [12]. Other findings in the USA, which reveal that 4.1% of pregnant women aged 15–44 report binge drinking in the past month, are broadly consistent [13,14]. This compares to a rate of binge drinking during the past month of 23.2% among nonpregnant women. Moreover, an Australian national survey revealed that 47% of pregnant and/or breastfeeding women were using alcohol up to 6 months post partum [15].

Illicit substance misuse

In the UK, since 6.1% of women aged 16–24 have used a class A drug and 20.6% have used any illicit drug in the past year, there is clear evidence that substance use in this population is an issue of real and potentially serious clinical concern [8].

There is some consistency from several US and Australian studies that report on substance use in pregnancy. The American National Pregnancy Health Survey found that 5.5% of pregnant women were using any illicit drug (cannabis, cocaine, amphetamines, opiates, inhalants, hallucinogens, nonmedical use of psychotherapeutics) [16]. A study using birth certificate reports of substance misuse showed 5.2% of pregnant women to be using illicit drugs [17]. The Australian National Drug Strategy Household Survey reported any illicit drug use in 6% of those women who stated that they were pregnant and/or breastfeeding in the last 12 months [18].

Opiates/opioids

Opiates/opioids/narcotics are taken orally (often from misuse of prescription medications), intravenously or intranasally. Intravenous heroin is a short-acting drug with a half-life of minutes. Withdrawal may begin in as little as 6–8 hours after the last dose is taken. The reported prevalence of opiate use during pregnancy ranges from 1.6% to 8.5% [19,20]. The Maternal Lifestyle Study in the USA [21] reported a prevalence of 2.3% detected through meconium analysis, though there was considerable variation (1.6–7.2%) in the reported prevalence.

Cocaine

Cocaine can be snorted, injected intravenously or subcutaneously or smoked and inhaled as crack cocaine. It is a short-acting drug with peak levels in 15–60 minutes. It readily crosses the placenta. The reported prevalence varies from 0.3% [22] to 9.5% [21]. Cocaine exposure in the UK was reported as less than 1.1% among pregnant women [23–25]. Based on maternal self-report and meconium analysis, one American study reported 9.5% exposure to cocaine [21] while another reported 1.1% of pregnant women to be using this substance [16].

Cannabis

Marijuana is generally inhaled through smoking. Cannabis use among pregnant women varies greatly, from 1.8% [22] to 15% [23]. Between 8.5% and 14.5% of pregnant women in urban UK samples are smoking cannabis at 12 weeks gestation [24,25]. In a perinatal sample from Glasgow, meconium analysis showed that 15% of mothers had used cannabis in the second or third trimester [23] compared with 7.2% in a multicenter American study [21]. The Australian study reported that 5% of those women who stated that they were pregnant and/or breastfeeding in the last 12 months had used cannabis [18]. Since cannabis was used by 16.6% of women aged 16–24 years and 5.9% of those aged 16–59 years during the last year in the UK, the potential impact on the fetus must be considered [8].

Amphetamine

Methamphetamine use is increasing throughout the world. It is used clinically to treat attention deficit hyperactivity disorder. It comes in different forms that may be smoked, swallowed, snorted or injected and may be known as meth, speed or crank. It can be manufactured from common cough and cold remedies. The effects are similar to cocaine but often accompanied by hallucinations. The half-life is much longer than that of cocaine, ranging from 10 to 20 hours. While data about the use of these agents in pregnancy are still evolving, there appear to be an increasing number of infants in Western countries who were exposed to these agents in utero.

Cigarette smoking

Similar methodologic issues to those described above pertain to smoking estimates. However, in industrialized countries, between 20% and 30% of pregnant women report smoking [26]. Between 11% and 48% of pregnant smokers quit at some stage during pregnancy [27–30]. In the UK, an estimated 27% of pregnant women continue to smoke throughout pregnancy [31]. Up to a quarter of women who smoke before pregnancy are likely to stop before their first antenatal visit without professional help. A further 10% are likely to stop following their first antenatal visit. However, the majority of those who do not quit prior to becoming pregnant continue to smoke [32].

The interactions of substance misuse with health are multiple and complex. The effects may be very rapid or insidious, by a direct pharmacologic or physiologic action or indirectly due to associated behaviors. Substance misuse, which may involve a range of substances, must be seen in the context of social and medical difficulties. These may include poor diet and nutrition and/or chaotic lifestyle, e.g. homelessness, social isolation, social deprivation, and medical and psychiatric complications [41–43].

Practitioners working with substance misusers need to be aware of the relationship of a history of substance misuse to presenting physical or psychologic problems such as coma, confusion, delirium, memory problems, fever, agitation, convulsions, tremor, paranoia or hallucinations. Substance misusers may have vascular, infectious, carcinogenic or traumatic conditions directly related to their misuse. This may connect previous difficulties to a current acute presentation for which life-saving measures could be required. For these reasons, it is obligatory to establish whether recent substance use (including the types, quantities, route and the time course of use) may have a bearing on overt and covert physical and psychologic symptomatology. Even where the incidence of serious adverse effects is low, it is the unpredictability of these events that makes the health consequences significant.

Alcohol, drugs and nicotine affect all organs of the body, but a detailed account of these physiologic effects is beyond the scope of this chapter [1]. The acute effects of intoxication, as well as the impact of chronic use and including the development of withdrawal and dependence, can lead to an array of physical and psychologic problems and social consequences. Dependence on some substances can develop very rapidly, within weeks or months. Intoxication, addiction and perhaps even an underlying tendency to seek out risk may all work together to further increase high-risk behaviors such as injecting drug use, needle sharing, unsafe sex and the repeated use of substances to the point of intoxication (e.g. binge drinking). The psychologic symptoms or psychiatric syndromes may be either cause or effect. These include behaviors such as impulsivity, aggression and disinhibition and disorders including anxiety, depression, psychotic illness, post-traumatic stress disorder, personality disorder and eating disorders. Self-harm may result, with eventual suicide. These difficulties can lead to homelessness, unemployment, poverty and criminality, as well as disengagement from families, communities and services. Patients with co-morbid conditions have a poorer prognosis and place a heavy burden on services because of higher rates of relapse and rehospitalization, serious infections such as hepatitis and HIV, prostitution, violence, arrest and even imprisonment.

It should be borne in mind that co-morbid conditions might constitute up to 75% of some clinical populations [36]. In the National Treatment Outcome Study [37], as in other studies, females were more likely to report a co-morbid psychiatric condition, especially depression or borderline personality disorder, whilst males were more likely to suffer from antisocial personality disorder. Compared with controls, pregnant women with affective disorder or schizophrenia still smoke very heavily [44].

The impact of ethnic and cultural factors must be considered when undertaking an assessment of pregnant women, as their substance-using behavior may be a marker of other attitudes and behaviors that could influence their perceptions of pregnancy and health. In the UK, ethnic minorities use alcohol less than whites, but those of mixed ethnicity use drugs more frequently [45–48].

Long-term developmental neurocognitive, physical and psychosocial effects resulting from in utero exposure to opioids and other drugs are poorly understood. Moreover, it is increasingly common that substance misusers take a combination of different drugs at different times during their pregnancy and, because of the complex psychosocial context in which they use substances, such research can face serious methodologic problems. However, generally, parental substance misuse poses significant risks for children. Child and adolescent mental health services report that a parent’s long-standing drug and/or alcohol misuse is a substantial risk factor for poor mental health in children [92]. Children may also be at high risk of maltreatment, emotional or physical neglect or abuse, family conflict, and inappropriate parental behavior [93–95]. Children may be exposed to, and involved in, drug-related activities and associated crimes [96]. They are more likely to display behavioral problems [97], experience social isolation and stigma [98], misuse substances themselves when older [99], and develop problem drug use [100].

Parents with chronic drug addiction spend considerable time and attention on accessing and using drugs, which reduces their emotional and actual availability for their children. Conflicting pressures may be especially acute in economically deprived, lone-parent households and where there is little support from relatives or neighbors [101]. In the long term, children of substance-misusing parents may have severe social difficulties, including strong reactions to change, isolation, difficulty in learning to have fun and estrangement from family and peers [95]. Despite this, substance misusers should not automatically be stereotyped as poor parents.

Pregnancy may motivate individuals to spontaneously modify their behaviors or to be susceptible to advice for the health of the baby [102]. Indeed, about two-thirds of American women who drank prior to conceiving, as well as up to 40% of those who smoked, stopped spontaneously during pregnancy [103]. In the USA, the 1995 behavioral risk factor survey showed that 51% of women of childbearing age drank prior to pregnancy, but only 16% drank during pregnancy [103]. A telephone survey of pregnant women found that 65.6% were drinking before pregnancy compared with 5.2% during pregnancy [104]. Hispanic ethnicity and younger age were significantly associated with spontaneous alcohol abstinence. The Australian national data [18] showed that women who were pregnant either abstained from alcohol (38%) or drank less (59%). It is encouraging to note that only 3% continued to drink the same amount of alcohol after becoming pregnant.

Among those who smoked prior to pregnancy 39% quit after becoming pregnant, a rate eight times that reported among smokers in the general population [105]. Among low-income, predominantly unmarried American women, spontaneous cessation of smoking and alcohol was reported by 28% and 80% of the women respectively. Factors associated with decreased likelihood of spontaneous smoking cessation in pregnancy such as less education [27,106], less concern about the effects of smoking on the fetus [107], worse mood or emotional well-being [108], having partners who smoke [109,110], and greater severity of addiction [27] could also be relevant to other substances.

Research has also shown that up to 60% of those who stop smoking when pregnant will return to smoking within the first 6 months post partum and 80–90% will have experienced a relapse by 12 months post partum [105,111]. There is some indication that this might be applicable to drugs and alcohol. A longitudinal study of pregnant substance users found that the use of cigarettes, alcohol and marijuana was lowest during pregnancy, increased sharply at 6 months post partum and remained level at 12 months post partum [112]. Although the evidence demonstrates that the proportion of women using substances is less at term compared with in the early stages of pregnancy, which might indicate that use of substances diminishes as pregnancy advances, this has not been studied in a longitudinal design over the long term.

The main objectives of a pregnant drug users (PDU) service are a safe pregnancy with a healthy baby and mother – the welfare of both the unborn child and the mother is a paramount consideration. In order to achieve this, promotion of engagement with substance misuse treatment and antenatal care within a co-ordinated framework is a key concern (Box 19.4). This should involve different phases of reproductive healthcare: preconception, pregnancy, childbirth and postnatal (including parenting) [113]. In this chapter we will focus on management during pregnancy and childbirth.

In order to develop the optimal treatment plan, the substance problem must be recognized by professionals and acknowledged by the patient. It is well documented that a substantial number of women treated in obstetric settings have unrecognized and untreated psychiatric disorders, as well as substance use [114].

All pregnant women should be screened for substance misuse. Questions should be asked in a nonjudgmental manner, beginning with inquiries about legal substances, followed by illegal ones beginning with marijuana. Patients who admit to substance misuse should be asked to quantify their use and about route of administration. As terminology varies by region and changes with time, practitioners should be comfortable asking patients to explain terms with which they are unfamiliar [224, 227].

The most important issue is to be able to determine whether patients are engaging in harmful use or are dependent on one or more substances. This differentiation is critical in terms of decisions around the selection of appropriate treatment interventions (in terms of type and intensity) and suitability of settings. It is also important when designing and assessing research because a range of terms may be used that do not equate to each other, so that the findings are not comparable.

Whatever the available options, they need to be discussed and agreed with the patient, the patient’s partner (if feasible), and the multidisciplinary team. Regular individual monitoring and attendance are a priority. Liaison with other services is essential. Group work has the benefit of providing a social network and group cohesion, and may more efficiently support both health education (about effects of substance misuse on mother and baby, diet and nutrition, health visitors, sexual health), and support with core problems (e.g. housing, benefits). However, some mothers prefer individual treatment.

Available options