Pregnancy outcome in women who use opiates

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Abstract

Background

Opiate use in pregnancy is on the increase. There are a number of complications associated with this problem but current data from UK centres are sparse.

Design

A retrospective study.

Setting

A North of England Hospital.

Methods

Maternal and neonatal case records were studied and a standard data set completed.

Main outcome measures

Maternal and neonatal outcomes were classified by the woman's drug usage at the end of pregnancy.

Results

One hundred and ten babies born to 108 women were studied and 41% had evidence of previous exposure to the hepatitis C virus.

Women who took heroin in later pregnancy were significantly more likely than women who were stabilised on methadone to have a baby who needed morphine (40% versus 19%), had higher mean maximum neonatal abstinence scores (NAS) (5.8 versus 4.7) and stayed in the neonatal unit significantly longer (mean 17.2 days versus 11.8 days).

There were two neonatal deaths and the overall rate of prematurity was 29%.

Conclusions

The outcome for pregnancy in women who use opiates is complicated by high rates of prematurity and neonatal death. Women who used heroin in later pregnancy had babies who developed more severe NAS and needed a longer hospital stay than women who used only methadone.

Introduction

Substance abuse in the general United Kingdom population has reached a significant level and obstetricians and neonatologists are confronted daily with the effects of drugs on their patients.

Heroin use is common amongst drug users in East Yorkshire and it is usually injected intravenously. Heroin and the opiate often used as substitution therapy, methadone, when used in pregnancy have been associated with an increased risk of perinatal mortality [1], [2], pre-term delivery and low birth weight [1], [3], [4] compared to non-users.

Significant numbers of babies who are exposed to opiates in pregnancy have signs of withdrawal in the neonatal periods [5], [6], [7].

Also these mothers, their babies and the health care workers looking after them are at increased risk of blood-borne infectious diseases such as hepatitis B, hepatitis C and HIV [8], [9], [10].

There are a number of treatment strategies, which can be offered to women who use heroin in pregnancy, of which methadone use is one.

Methadone, a synthetic derivative of opium, is available to treat heroin dependant women and is licensed in the United Kingdom.

A methadone programme theoretically offers the benefit of improving the neonatal outcome, reduces heroin use and improves the overall health of these women. However, these benefits may be obviated if high doses of methadone are employed or where inadequate doses are prescribed and heroin is used on top.

Methadone use results in babies with low birth weight who may develop the neonatal abstinence syndrome (NAS) [11]. The severity of the NAS is scored using a scale of 0–10 as described by Rivers [12] and treatment with triclofos instituted for a score of greater than 2. If the NAS score is greater than 6 morphine treatment is instituted.

In the UK there is an increased uptake of methadone prescribing programmes for heroin addicts and its prescription is available in many general practices.

In Hull pregnant heroin users are offered a multidisciplinary, non-judgemental approach to their care in pregnancy by a dedicated team, which includes obstetricians, paediatricians, midwives and social workers.

Mothers who are actively taking heroin while pregnant are offered a methadone substitution programme with a starting dose based on the quantity of heroin intake per day. Once stabilised on methadone and abstinent from heroin, women are offered either maintenance throughout pregnancy or a slow reduction in methadone dosage of the order of 2 mg/2 weeks’ reduction in the daily dose. Also, women who are already on a methadone programme are offered the above options along with ongoing support and encouragement. Despite this holistic approach some women cannot tolerate the methadone dose reduction and use heroin as a top-up.

Data on pregnancy outcome in women who use opiates in pregnancy in the United Kingdom are still sparse with the introduction of methadone programmes in the country coupled with recent advances in neonatal medicine older data may therefore not represent current practice.

This retrospective study was conducted to assess the pregnancy outcome in women who have used opiates and who were cared for by a multidisciplinary team who use a methadone substitution programme as treatment.

Section snippets

Local audit committee approval was granted

This study was carried out at Hull Maternity Hospital and The Women & Children Hospital, Hull. The study covers a period from January 1997 to September 2003.

With the assistance of the hospital audit facilitator, the antenatal clinic records and those of the multidisciplinary team were searched for patients who were recorded as ‘ever’ used illicit drugs excluding cigarettes, cannabis or alcohol.

A list of such patients was created. The records of these patients were then checked to identify and

Results

One hundred and eight women delivered 110 babies (two sets of twins) therefore the data set refers to 52 women taking methadone and 54 babies exposed to methadone.

Women taking methadone alone (n = 52) and taking heroin either alone or in combination with other drugs including methadone (n = 47) were compared. Nine women could not be categorised and analysed as they were drug free or their drug usage was not known due to persistent defaultment from antenatal care, imprisonment or moving out of the

Discussion

Substance abuse in the United Kingdom is a public health issue, but there is a lack of well-conducted research into opiate use in pregnant women. In this study, a woman's drug usage was characterised by her disclosure to her team of carers and not checked by routine urine testing. There could be errors of disclosure of heroin use in some cases but it is believed that most of the women were categorised accurately and those where there was doubt placed in the unknown group. Methadone, when

Conclusion

Opiate use in pregnancy is associated with premature labour and neonatal complications. With adequate social support, special antenatal care and neonatal care the pregnancy outcome in these patients is only slightly worse from that of the general population.

It is noteworthy that the pregnancy outcome among pregnant opiate users in the United Kingdom compares favourably to other industrialised countries. This possibly reflects the impact of social support and possibly the methadone substitution

References (17)

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    Infants prenatally exposed to illicit opioids (Azuine et al., 2019; Nygaard et al., 2017) and/or MAT (Konijnenberg and Melinder, 2011; Nelson et al., 2020) have lower average birth weights than non-exposed infants. Similarly, prenatal opioid exposure has been linked to shorter gestational age and higher risk for preterm birth among infants whose mothers used heroin (Azuine et al., 2019; Fajemirokun-Odudeyi et al., 2006) and/or MAT (Fajemirokun-Odudeyi et al., 2006; Lejeune et al., 2006; Nelson et al., 2020) than among infants without such exposure. Although neonatal risks are well-established, less is known about neurodevelopmental outcomes of prenatal opioid exposure beyond the first few weeks of life.

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