• Alcohol;
  • pregnancy;
  • substance use

The work by Friguls et al. [1] addresses two issues of great clinical importance: drug use during pregnancy and the reliability of self-report for such use. The use of psychoactive substances during pregnancy has potentially serious clinical sequelae for fetal development [2,3]. Clearly, accurate reporting of such use during gestation is a vital component of clinical management during pregnancy.

In the broader drug field, self-report among illicit drug users has been demonstrated repeatedly to be highly reliable in research conditions, where there is no motivation to lie, and in clinical settings where there are no negative consequences attached to truthful reporting [4,5]. In the case of pregnancy, however, there is clear motivation to conceal substance use, due to the stigma associated with such use. Friguls et al. report that 2% of their sample reported recent illicit substance use, while 16% tested positive in hair analyses [1]. The clinical importance of these positive cases is unclear, however, as the intensity or frequency of use was not measured. We do not know if a detected substance was deposited from a single-use episode, sporadic use or high-frequency use. The clinical implications of these different use patterns are markedly different. We should also be careful in assuming that detected drugs were consumed after the women were aware that they were pregnant. Despite these uncertainties, there were some observed differences between the newborns of illicit drug-using mothers and others: shorter birth length for newborns of mothers who had had illicit drugs detected, and smaller head circumference for babies of cocaine-positive mothers.

While the focus of this study was on illicit drugs, it is the high levels of alcohol and tobacco use reported by these women that stands out. Approximately two-thirds were smokers, and a third reported alcohol use during their pregnancy. These substances, in and of themselves, may affect fetal development [5,6]. Not surprisingly, given all we know of polydrug use patterns, the use of these substances was associated strongly with the use of illicit drugs. Unfortunately, no multivariate analyses were performed, so we are unable to determine the role of illicit substances themselves upon birth characteristics after taking into account the effects of alcohol and tobacco.

Studies of maternal drug use raise ethical questions concerning what are appropriate clinical responses. Do we mandate hair testing for all mothers? Even if this were feasible, hair analysis is affected adversely by agents such as hair dyes and bleach. Given that a 1-cm length of hair roughly measures use during a month, short hair could well become extremely fashionable among pregnant women. Friguls and colleagues recommend voluntary screening during pregnancy. The question must be asked: who would have a screen performed voluntarily: illicit users or those who have ‘nothing to hide’? Indeed, what do we do if a test is positive? There is no point in conducting tests if there is no clinical follow-up.

The use of biomarkers can never be a substitute for good clinical rapport and management. Clinicians should be aware that illicit use is likely to be under-reported, particularly when admitting such use may lead to opprobrium or negative consequences. In the area of pregnancy these consequences are indeed far-reaching, with separation from one's children a real possibility. Most importantly, as this study demonstrates, we must not ignore licit substance use, which will occur among far more expectant mothers than will illicit use. Despite the focus on illicit drugs, it is alcohol that is associated most clearly with harm, now recognized as responsible for fetal alcohol spectrum disorders [7]. The association between licit and illicit use may well provide clinicians with a means to discuss illicit substance use with their patients. Those who smoke, for instance, are more likely to use other drugs, and these could be discussed within the broad context of substance use and maternal health. The key is to create a clinical environment in which honesty is not punished, but used a means to discuss the potential harms of maternal use upon the fetus.


  1. Top of page
  2. Declarations of interest
  3. References