Shares fell about 2 percent to $44.35 in extended trading.

Revenue was also weighed down by weaker capital markets in Asia and the impact of the U.S. tax overhaul on the EMEA unit, the company said.

Total revenue fell 1 percent to $15.66 billion (£12.09 billion), missing analysts' average estimate of $15.93 billion, according to IBES data from Refinitiv.

The results capture a quarter that analysts had anticipated would be challenging for many life insurers, whose massive investment portfolios were caught in the whims of tumultuous markets toward the end of 2018.

Life insurers amped up risk taking in recent years, moving away from safer investments like Treasury bonds, as interest rates remained near rock-bottom levels.

The S&P 500 index tumbled about 14 percent during the final three months of 2018, while the MSCI All-World Index dropped 13.21 percent during the period.

MetLife's net investment income slid to $3.46 billion from $4.45 billion a year earlier, driven by changes in the estimated fair value of certain securities. Adjusting for those changes, net investment income rose 7 percent.

Net income fell to $2 billion from $2.3 billion.

Earnings at the company's U.S. retirement business more than doubled, buoyed by volume growth, higher investment margins and lower taxes, helping overall adjusted profits rise 38 percent in the region.

Excluding one-time items, MetLife earned $1.35 per share. Analysts on average had expected earnings of $1.28 per share.

(Reporting by Diptendu Lahiri in Bengaluru; Editing by Sai Sachin Ravikumar and Sriraj Kalluvila)