American Equity Investment Life Holding Co. (AEL) on Wednesday reported first-quarter operating income of $29.8 million, or 46 cents per share, compared with of $30.6 million, or 47 cents per share, in 2011.

The West Des Moines-based insurer’s annuity sales for the first quarter were $979 million, down from $1.3 billion in the year-ago quarter. AEL attributed the relative decrease to larger-than-usual sales last year due to higher annuity purchases in advance of an interest rate decrease on the products.

Total invested assets grew 15 percent to $24 billion as of March 31, compared with $20.8 billion on March 31, 2011.