1 Background

Substance use disorder in pregnancy is a critical public health concern that is linked with several adverse maternal and newborn health outcomes including preterm birth (PTB), low birth weight (LBW), and small for gestational age (SGA) babies. The most widely used substances in pregnancy in high-, low-, and middle-income countries (LMICs) include tobacco, alcohol, cannabis, opiates, cocaine, and other illicit substances. This guidance has been developed to help health-care providers in identifying and managing smoking, alcohol, and substance use disorders in pregnant women and thereby reducing the risks of PTB and other adverse maternal and child health outcomes.

This guideline summarises information from the WHO, other guidance (where available), and recently conducted systematic reviews on the risks of and interventions for antenatal exposure to smoking, alcohol, and substance use for PTB.

2 Evidence Statement

Use of alcohol, tobacco, and other psychoactive substances during pregnancy leads to an increased risk of health problems for mother and child such as spontaneous abortion, stillbirth, low birth weight, birth defects, and prematurity (Table 1). Concurrent use of these substances (i.e. poly substance use) further increases the risk of adverse outcomes in all settings.

Table 1 Summary of evidenced tobacco, alcohol, and other substance use-related risk factors and interventions for PTB
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This guideline proposes interventions (Table 1) for the identification and management of the following:

  1. (i)

    Tobacco smoking and exposure to second-hand smoke (SHS) (protection from SHS in homes and public places, screening, psychosocial, and pharmacological).

  2. (ii)

    Alcohol and illicit substance use (screening and dependency management) in pregnant women during the antenatal period.

Despite gaps in research and knowledge, the potential benefits of the recommended actions may help improve PTB and other birth outcomes.

3 Synopsis of the best Evidenced Risk Factors for Preterm Birth

For a summary of the evidence of tobacco, alcohol, and substance use-related risk factors for preterm birth, please see Table 1, in Sect. 5.

3.1 Smoking and Exposure to Second-Hand Smoke

  1. (i)

    A systematic review and meta-analysis (2000) of prospective studies for any maternal tobacco smoking versus no maternal smoking and preterm delivery found the pooled odds ratio to be 1.27 (95% CI 1.21–1.33, 20 studies, >100,000 participants) [1]. All the studies were conducted in high-income countries (HICs).

  2. (ii)

    A meta-analysis (2016) reported the ORs of PTB for women who were ever exposed to passive tobacco smoking versus women who had never been exposed to passive smoking at any place and at home were 1.20 (95% CI 1.07–1.34, 24 studies, 88,200 participants) and 1.16 (95% CI 1.04–1.30, 11 studies, 73,211 participants), respectively [2]. The associations were statistically significant for studies conducted in Asia (OR 1.26, 95% CI 1.05–1.52) [2]. Several studies were from low- and middle-income countries (LMICs) including China, India, Korea, and Indonesia.

  3. (iii)

    A systematic review and meta-analysis of observational studies in India also indicated that 0.19 million PTB (6% of all PTBs) could be attributed to the use smokeless tobacco (SLT) (pooled OR 1.39, 95% CI 1.01–1.91, 2 studies, 1800 participants) [3].

3.2 Alcohol Use

A dose-response relationship between alcohol consumption during pregnancy and the risks of PTB was observed in a meta-analysis (2011) of 14 observational studies (n = 280,443 pregnant women) primarily in HICs [4]. Compared with mothers who do not drink, the overall dose-response relationships for PTB showed (i) no effect up to 18 g pure alcohol or an average of 1.5 drinks/day and (ii) 23% increase in risk at an average of three drinks or 36 g/day (RR 1.23, 95% CI 1.05–1.44) [4].

3.3 Substance Use

  1. (i)

    Two systematic reviews (2016) were identified that explored maternal cannabis/marijuana use and the risks of preterm birth [5, 6]. No association was demonstrated between in utero exposure to marijuana/cannabis and PTB (pooled OR 1.29, 95% CI 0.80–2.08, 9 studies) compared to non-users [6]. Three studies included in the review showed an increase in odds of PTB, while six showed no association. Only two studies included were from LMICs—Iran and Jamaica [6]. Although marijuana use during pregnancy was associated with an increased risk of PTB in the pooled unadjusted analysis, (15.3% compared with 9.6%, pooled RR 1.32, 95% CI 1.14–1.54), results were found to be insignificant after adjusting for tobacco use and other confounding factors (pooled RR 1.08, 95% CI 0.82–1.43) [5].

  2. (ii)

    Opiate use (heroin, opium) is associated with an increased risk of premature birth and a number of other maternofoetal adverse outcomes. Findings from observational studies show that, compared to cocaine or opiate non-users, opiate users were 2.86 times as likely (95% Cl 1.11–7.36; p = 0.03) to deliver preterm [7]. Similar results were also seen in other observational studies conducted in Iran [8] and low-income, multi-ethnic US population [9].However research is heavily skewed to high-income country settings.

  3. (iii)

    Crack cocaine use during pregnancy was associated with significantly higher odds of preterm delivery (OR 2.22, 95% CI 1.59–3.10) [10]. Eight observational studies were included (n = 5761) in the meta-analysis; only one was from a LMIC (Iran) [10]. Systematic review and meta-analysis of 24 observational studies in HICs (n = 39,860) shows that cocaine use during pregnancy was associated with significantly higher odds of PTB (OR 3.38, 95% CI 2.72–4.21) [11].

  4. (iv)

    A significant increase in unadjusted risks of PTB (OR 4.11, 95% CI 3.05–5.55, 5 studies, n = 62,070) was identified among women exposed to amphetamines in pregnancy. All five studies included in the review were from HICs [12].

4 Practical Clinical Risk Assessment Instructions for PTB

4.1 Health-care providers should ask all pregnant women about their use of alcohol and other substances (past and present) early in pregnancy and at every antenatal visit. WHO recommends the use of validated screening instruments for this purpose [13, 14]. There may be cultural taboos which compound stigma and other difficulties in disclosure of substance use such as fear of judgement by health-care providers, breach of confidentiality, and fear of child removal after the birth.

4.2 All guidance encourages health-care practitioners to explore these issues sensitively, using a non-judgemental approach and in a confidential environment. There may, however, be child safeguarding issues which arise during this assessment which should be dealt with using in-country mechanisms, while optimising maternal physical and mental health. The presence of family members during maternal health checks may also act as a barrier to full disclosure.

4.3 Listed below are screening instruments that have been suggested to be used for prenatal assessment of pregnant women [13, 14]. There are variations in the tools regarding number of items, administration method (paper and pencil, computer), training needed, and location (prenatal clinic/outpatient/inpatient). Although some of the tools were validated, they will need to be further validated before use in an LMIC context.

  • Tobacco, alcohol, and substances: Alcohol, Smoking, and Substance Involvement Screening Test (ASSIST Version 3.0); Pregnancy Information Program (PIP).

  • Alcohol and General Substance Use: 4P’s Plus [15]; Substance Use Risk Profile—Pregnancy (SURP-P) [16].

  • Alcohol: Alcohol Use Disorder Identification Test (AUDIT) [17]; Alcohol Use Disorder Identification Test—Consumption (AUDIT-C) [18]; CAGE [19]; Short Michigan Alcohol Screening Test (SMAST) [20]; Ten Question Drinking History (TQDH) [21]; T-ACE [22]; TWEAK [23].

5 Evidenced Effective Interventions for Risk Factors for Preterm Birth

These are summarised in Table 1.

6 Summary of Interventions for Smoking and Second-Hand Exposure to Smoke (Table 2)

Table 2 Benefits statements of effectiveness of smoking cessation interventions to prevent preterm birth
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7 Summary of Interventions for Alcohol and Substance Use (Table 3)

Table 3 Benefits statements of effective interventions to promote harm reduction to prevent preterm birth
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8 Research and Clinical Practice Recommendation

There is strong consensus within the literature about the negative effects of alcohol, tobacco, and substance use during pregnancy, and all women should receive necessary interventions to stop (preferably) or reduce use. The evidence is of low quality, and further primary research and controlled trials are needed on effective ways to assess exposure and the use of alcohol, tobacco (including second-hand exposure), and substances; measure the effect on maternal and child health outcomes and for determining the effectiveness and cost-effectiveness of recommended interventions in pregnancy. Additionally, there is also a dearth of studies conducted in LMICs. Assessment methods should include and integrate findings from policy, public health, behavioural and implementation science, and trials of interventions where PTB is the primary outcome measure. In addition, longitudinal cohort studies which include consideration of multi-factorial psychosocial factors are needed to assess the risks on women, children, and future generations.