The Safety of Maternal and Fetal MRI at 3 T.

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. 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 test. Hearing impairment between groups was compared by Fisher exact test. There was no significant difference in mean birth weight between the MR-exposed (3398 g) and control (3510 g) neonates ( = 0.06). There was no significant difference in prevalence of hearing impairment ( = 0.55) between the MR-exposed (0% [0/81]) and control (1.8% [3/162]) groups. 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.