The Safety of Maternal and Fetal MRI at 3 T.

OBJECTIVE. The purpose of this study was to evaluate the effects of clinical 3-T MRI during pregnancy on fetal growth and neonatal hearing in neonates at low risk of congenital hearing impairment or of brain or chromosomal abnormalities. MATERIALS AND METHODS. This single-center retrospective case-control study included consecutively born healthy neonates exposed in utero to 3-T MR during MRI for maternal or fetal indications and born between January 2008 and March 2015. Each exposed neonate was randomly matched 1:2 by birth date to healthy control neonates who had not been exposed to MR. Infant birth weights were compared by unpaired t test. Hearing impairment between groups was compared by Fisher exact test. RESULTS. There was no significant difference in mean birth weight between the MR-exposed (3398 g) and control (3510 g) neonates (p = 0.06). There was no significant difference in prevalence of hearing impairment (p = 0.55) between the MR-exposed (0% [0/81]) and control (1.8% [3/162]) groups. CONCLUSION. This study showed no adverse effects with regard to neonatal hearing or fetal growth in healthy neonates who were variably exposed to 3-T MR in utero during MRI for various clinical maternal or fetal indications at any gestational age.