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Maternal methadone opioid maintenance therapy may be tied to smaller postnatal head circumference



Opioid maintenance therapy with methadone during pregnancy may be associated with a significantly smaller postnatal head circumference percentile, compared with opioid maintenance therapy with buprenorphine, according to a study presented at the Pregnancy Meeting.

Dr. Jay Davis, of Stony Brook University in New York Jake Remaly/MDedge News

Dr. Jay Davis

Antenatal ultrasound measurements do not differ by treatment, however, the researchers said. A separate study suggests that serial ultrasound examinations of fetal brain and biometry measurements may not be helpful in patients who receive these medications for opioid use disorder.

To examine the effects of methadone and buprenorphine opioid maintenance therapy on prenatal and postnatal growth parameters, Jay Davis, MD, a maternal-fetal medicine fellow at Stony Brook University in New York, and coinvestigators conducted a retrospective cohort study using medical records from an academic center during 2007-2017. They included women with singleton pregnancies receiving opioid maintenance therapy with methadone or buprenorphine. They compared head circumference percentile, abdominal circumference percentile, head circumference/abdominal circumference ratio, and postnatal head circumference percentile between the two groups. The investigators analyzed the data using the Wilcoxon–Mann–Whitney test, chi-square test, and logistic regression.

Pregnant woman taking large medication pill nd3000/iStock / Getty Images

The researchers studied 282 cases, including 120 patients who received buprenorphine and 162 who received methadone. Patients who received buprenorphine delivered at a later average gestational age (39 weeks vs. 37.8 weeks) and had newborns with greater average birth weights (3,206 g vs. 2,877 g). Compared with patients who received methadone, patients who received buprenorphine were significantly more likely to have a larger postnatal head circumference percentile (39 vs. 30), Dr. Davis and colleagues reported. This difference remained significant after controlling for race, prescriber, gestational age at delivery, and birth weight.

In a separate study presented at the meeting sponsored by the Society for Maternal-Fetal Medicine, Jose M. Perez Yordan, MD, of the University of New Mexico, Albuquerque, and colleagues examined effects of medications for opioid use disorder on fetal brain and body measurements.

They found that maternal medications for opioid use disorder do not have a clinically significant effect on fetal brain and body measurements, compared with controls. “No consistent pattern of decreased fetal growth was identified, since the body measurement affected did not persist with serial ultrasounds,” they said. “Serial ultrasound examinations do not appear to be helpful in patients” who take medications of opioid use disorder, with or without alcohol coexposure, unless other risk factors are present.

Dr. Jose M. Perez Yordan, of the University of New Mexico in Albuquerque Jake Remaly/MDedge News

Dr. Jose M. Perez Yordan

To evaluate the effects of medications of opioid use disorder and alcohol coexposure on fetal brain and biometric measurements at the second- and third-trimester ultrasound measurements, the investigators are conducting a prospective study known as ENRICH-1. The study includes healthy controls, patients taking medications of opioid use disorder (that is, buprenorphine or methadone), and patients taking medications of opioid use disorder with alcohol coexposure.

Ultrasound measurements from the second and third trimesters evaluated biparietal diameter, femur length, frontal lobe width and length, front-thalamic distance, and caval-calvarial distance. Univariate and multivariate analyses assessed differences in measurements adjusting for gestational age and other factors.

The present analysis included data from 171 participants, including 56 healthy controls, 75 patients taking medications of opioid use disorder, and 40 patients taking medications of opioid use disorder with alcohol coexposure. There was no consistent pattern of decreased fetal growth. Affected measurements did not persist over time.

The study presented by Dr. Perez Yordan was supported by a National Institute on Alcohol Abuse and Alcoholism grant. The remaining investigators in both studies had no relevant financial disclosures.

SOURCE: Perez Yordan JM et al. Am J Obstet Gynecol. 2020 Jan;222(1):S110, Abstract 149; Davis J et al. Am J Obstet Gynecol. 2020 Jan;222(1):S430, Abstract 678.

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