Update: Thanks to a downward adjustment in the final Nielsen data, Thursday’s “Reign” settled at the same 0.6 adults 18-49 rating delivered by last week’s broadcast.

Its viewership tally sank to 1.62 million viewers.

Benefiting from an upward adjustment in the finals, The CW’s 8PM staple “The Vampire Diaries” officially clocked in at a 1.1 adults 18-49 rating with 2.42 million viewers.

Update: Despite declining slightly in the overnight metered market ratings, The CW’s “Reign” held steady–and possibly increased–in the pivotal adults 18-49 demographic.

According to Nielsen’s Fast National data, “Sacrifice,” this week’s episode, delivered a 0.7 adults 18-49 rating. Last week’s episode posted the same 0.7 in adults 18-49 but was adjusted down to a 0.6 in the finals.

Highly unlikely to face a larger adjustment this week, “Reign” will either match or beat last week’s adults 18-49 number in the final Nielsen data.

Viewership fell slightly to 1.69 million.

Welcome in any situation, the ratings stability is particularly comforting given rumors that fans were boycotting the episode. It is made further impressive by the fact that “Reign” received weakened lead-in support from “The Vampire Diaries,” which declined to a 1.0 rating with 2.36 million viewers.

After two weeks of steadiness in the overnight metered market ratings, The CW’s “Reign” suffered a slight decline for Thursday’s episode.

One should hesitate before sounding the alarm.

“Sacrifice,” Thursday’s episode, garnered a 1.3 overnight household number. Down from the 1.4 posted by the previous two airings, the number was in line with that drawn by the “Left Behind” episode on December 5.

That December 5 episode, however, posted the same 0.6 adults 18-49 rating as the two that followed it. November 14 episode “A Chill in the Air,” which also garnered a 1.3 overnight metered market rating, actually ended up posting a 0.7 in the coveted young adults demo. To date, no episode that delivered a 1.4 in the overnights scored more than a 0.6 in adults 18-49.

This week’s decline to a 1.3, therefore, makes no guarantee of an accompanying drop in the adults 18-49 demographic. An assessment of this week’s performance–and commentary on whether the rumored boycott had any effect on viewership–must wait until the fast nationals are delivered at 11:30AM.

The CW’s 8PM flagship “The Vampire Diaries” fell by two tenths to a 1.7 metered market rating.