GlaxoSmithKline (GSK) has paused enrollment in three phase 3 trials evaluating its respiratory syncytial virus (RSV) maternal vaccine candidate in pregnant women.

The pause followed a recommendation from the independent data monitoring committee following a routine safety assessment, GSK said, but it did not disclose what safety signals were observed by the expert panel.

GSK said that the trial stoppages won’t affect an ongoing phase 3 trial evaluating a separate RSV vaccine in adults aged 60 and older. The British drugmaker expects to have results from that trial during the first half of this year.