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Home > Maternal and neonatal health among opiate users.

Long, Jean (2011) Maternal and neonatal health among opiate users. Drugnet Ireland , Issue 38, Summer 2011 , pp. 18-19.

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 Two recent papers present the results of studies on the health of women who had been prescribed methadone for the treatment of opiate dependence and their infants born in the Coombe Women and Infants University Hospital in Dublin. The first paper reported that the services of a liaison midwife were required to encourage pregnant women with opiate dependence to attend drug and maternity services regularly, and to liaise between professionals in both services. The second paper reported that the outcomes for mothers prescribed methadone and their new infants were not as good as those for other mothers and infants attending the maternity service. The key issues addressed in the papers are presented below.

Drug use in pregnancy: challenges for health care workers
This comparative study examined maternal and neonatal outcomes for pregnant women from the case load of a drug liaison midwife over the period 2002–2007,1 compared with outcomes in a similar study carried out in 1999–2000.2   

Of 524 women who attended the drug liaison midwife in the six-year period, 436 delivered a live baby after 32 weeks’ gestation who did not have congenital anomalies. All women were engaged with drug treatment and obstetric services.  
 
The 2002–2007 cohort was older (average age 25.9 years, range 17–32 years) and had marginally more pregnancies than the 1999–2000 cohort (average age 23.8 years, range 16–41 years). The 2002–2007 cohort attended their first antenatal visit earlier (at 15 weeks gestation) than the 1999 to 2000 cohort (at 18 weeks). Three-fifths of both cohorts attended five or more antenatal visits (satisfactory antenatal attendance). There were no maternal deaths among either cohort.
The average age at first heroin use was higher by one year (at 18 years) in the later cohort when compared to the earlier cohort. Opiate stability was marginally lower (50%) in the later cohort than in the earlier cohort (53%). Tobacco (91%), benzodiazepines (66%), alcohol (percentage not reported) and cocaine (71%) were commonly used alongside heroin by the later cohort. The rates of tobacco and benzodiazepine use were marginally lower, and the rate of cocaine use was higher, in the later cohort.
A very high proportion (93%) of the 2002–2007 cohort was taking prescribed methadone, compared to the 1999–2000 cohort (75%). The average dose of methadone at delivery was higher for the later cohort (60mg) than for the earlier cohort (39 mg). The average gestation at delivery was 38 weeks for both cohorts. The average birth weight was higher by 66g in the later cohort. The percentage of babies requiring admission to the special care baby unit had increased from 42% in the earlier cohort to 56% in the later cohort. The proportion of babies requiring treatment for neonatal abstinence syndrome was considerably higher in the later cohort (45%) than in the earlier cohort (29%). The babies’ average length of stay in the special care baby unit increased by over 2 days in the later cohort when compared to the earlier cohort.
The data indicate that opiate-dependent pregnant women and their infants are a very vulnerable group and require special care at both drug treatment and maternity hospitals. 
 
Methadone and perinatal outcomes: a retrospective cohort study
This study examined the relationship between methadone maintenance treatment and maternal characteristics, perinatal outcomes as well as neonatal abstinence syndrome.3 This was a retrospective cohort study of 61,030 singleton births at a large maternity hospital in the period 2000–2007 based on antenatal, delivery and postnatal records and the Central Treatment List (of clients prescribed methadone).
Of the 61,030 singleton births, 618 (1%) were to women who were prescribed methadone at delivery. Methadone-exposed women were more likely to be younger, unemployed, Irish, unmarried, have had previous pregnancies, have an unplanned pregnancy, to book antenatal care later than 20 weeks into pregnancy, to be current smokers and to drink alcohol before pregnancy. In addition, and as expected, a higher proportion of methadone-exposed women were likely to test positive for hepatitis B, hepatitis C and HIV when compared to non-exposed women (Table 1).
Table 1   Blood-borne viral status among the study populations by exposure to methadone
 
Exposed to methadone*
Non-exposed*
Hepatitis B positive serological status
20 (3.5%)
326 (1.0%)
Hepatitis C positive serological status
275 (48.2%)
193 (0.6%)
HIV positive
35 (5.8%)
171 (0.3%)
*The total number tested in each group is not presented in the paper.

 

Methadone exposure was associated with an increased risk of very preterm birth (before 32 weeks’ gestation), being small for gestational age (below the 10th percentile), admission to the neonatal unit, and diagnosis of a major congenital anomaly. There were four cases of Pierre Robin sequence among 618 methadone–exposed babies, compared to eight cases in 60,412 non-exposed infants. Although not statistically significant, the proportion of deaths within the first six weeks of birth was three times higher among the methadone-exposed group (2.4%) than the non-exposed group (0.8%).
There was a dose–response relationship between methadone and neonatal abstinence syndrome. As the dose of methadone increased so did the incidence of neonatal abstinence syndrome (Table 2). Preterm birth and small gestational age also predicted the presence of neonatal abstinence syndrome.
Table 2   Methadone dose and its relationship with neonatal abstinence syndrome (n=615)
 
Neonatal abstinence syndrome
 
Methadone dose in mg
Present
Absent
Adjusted odds ratios (95% CI)*
<21
19 (23.8)
61 (76.2)
1
21–50
73 (33.3)
146 (66.7)
0.9–3.5
51–80
117 (47.4)
130 (52.6)
1.6–6.53
81–100
26 (48.1)
28 (51.8)
1.3–7.5
>100
11 (73.3)
4 (26.7)
2.5–48.0
*Adjusted for preterm birth, gestational age, gender, maternal smoking during pregnancy and alcohol use before pregnancy
After controlling for known adverse socio-demographic factors, methadone exposure was found to be associated with an increased risk of adverse perinatal outcomes. Methadone dose at delivery was one of the important determinants of neonatal abstinence syndrome.
1. Carmody D,Geoghegan N, Sheppard R, Keenan E and O'Connell M (2011) Drug use in pregnancy: challenges for health care workers. MIDIRS Midwifery Digest, 20(4):  447–450.
2. Scully M, Geoghegan N, Corcoran P, Tiernan M and Keenan E (2004) Specialized drug liaison midwife services for pregnant opioid dependent women in Dublin, Ireland. Journal of Substance Abuse Treatment, 26(1): 27–33.
3. Cleary BJ, Donnelly JM, Strawbridge JD, Gallagher PJ, Fahey T, White MJ, Murphy DJ (2011) Methadone and perinatal outcomes: a retrospective cohort study. American Journal of Obstetrics and Gynecology, 204(2): 139.e1–9.

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