Fetal assessment in buprenorphine-maintained women using fetal magnetoencephalography: a pilot study.

BACKGROUND AND AIMS: In-utero exposure to opioids including buprenorphine (BUP) has been shown to affect fetal activity, specifically heart-rate variability (FHRV) and fetal movement (FM). Our objective was to extract simultaneous recordings of fetal cardiac and brain-related activity in BUP-maintained and non-opioid exposed pregnant women using a novel non-invasive biomagnetic technique.

DESIGN: A pilot study was conducted, recording and analyzing biomagnetic data from fetuses of BUP-maintained and non-opioid exposed pregnant women. Signals were acquired with the non-invasive 151-channel SARA (SQUID-Array for Reproductive Assessment) system. Advanced signal-processing techniques were applied to extract fetal heart and brain activity.

SETTING: University of Arkansas for Medical Sciences (UAMS, Little Rock, Arkansas, USA).

PARTICIPANTS: Eight BUP-maintained pregnant women from UAMS Women's Mental Health Program between gestational ages (GA) of 29-37 weeks who were treated with 8-24 mg of BUP daily. Sixteen pregnant women with no known opioid exposure in the same GA range were also included.

MEASUREMENTS: Outcome measures from the fetal heart and brain signals included: heart rate (FHR), FM, FHR accelerations, FHR-FM coupling, FHRV, fetal behavioral states (FBS) and power spectral density (PSD) of spontaneous brain activity. These measures were analyzed at three GA intervals.

FINDINGS: Fetal heart and brain activity parameters were extracted and quantified successfully from 18 non-opioid and 16 BUP recordings. Overall analysis in both groups show that: FHR and FM ranged from 131 to 141 beats per minute (b.p.m.) and 5 to 11 counts, respectively. In the 35-37 weeks GA, the coupling duration (~9 s) was the shortest, while three of the FHRV parameters were the highest. The PSD of brain activity revealed highest power in 0.5-4 Hz bandwidth. Transitions in FBS from quiet to active sleep were > 50% of sessions.

CONCLUSIONS: This pilot study showed that a novel biomagnetic technique allows simultaneous quantification of cardiac and brain activities of a group of buprenorphine-exposed and non-exposed fetuses in the third trimester.