Maternal opioid use disorder and neonatal abstinence syndrome in northwest Ontario: a 7-year retrospective analysis.

INTRODUCTION

Opioid use in pregnancy is increasing globally. In northwest Ontario, rates of neonatal abstinence syndrome (NAS) are alarmingly high. We sought to document the increasing rates of opioid exposure during pregnancy and associated cases of NAS over a 7-year period in northwest Ontario.

METHODS

We conducted a retrospective chart review at the Sioux Lookout Meno Ya Win Health Centre catchment area (population 29 000) maternity program in northwest Ontario of mother-infant dyads of live births from Jan. 1, 2009, to Dec. 31, 2015. The Integrated Pregnancy Program provides maternal, neonatal and addiction care for obstetrical patients at the health centre. We collected data on prenatal opioid exposure due to illicit and opioid agonist therapy (OAT) from patient/prescription histories and urine toxicology reports. Rates of NAS (diagnosed as a Finnegan score > 7) were recorded retrospectively from neonatal hospital charts.

RESULTS

There were 2743 live births during the study period. Opioid exposure occurred in 672 pregnancies (335 OAT, 337 illicit). The incidence of prenatal opioid exposure increased significantly between 2009 and 2012 (11.1% to 28.5%, < 0.001) but remained relatively constant at around 30% thereafter. Despite this, absolute rates of NAS remained relatively stable, with an average of 22.2 cases per 1000 live births over the study period. In comparison, the North West Local Health Integration Network (LHIN) experienced an average of 52.8 cases of NAS per 1000 live births in 2009-2012. The incidence of NAS in our centre decreased significantly over the study period (17.6% of opioid-exposed pregnancies in 2009 v. 4.0% in 2015, = 0.001). There was a gradual transition toward a preponderance of OAT- versus illicit-exposed pregnancies, increasing from 0% in 2009 to 76.9% in 2015 ( < 0.001).

CONCLUSION

Despite our continually increasing rates of opioid exposure in pregnancy, rates of NAS decreased annually and were substantially lower than those of our regional LHIN. In contrast to 2009, most opioid exposure in our region is now iatrogenic as a result of OAT. These improvements may be attributable in part to the rural community-based prenatal and addictions services developed in our catchment area.