Century Bancorp boosted net earnings slightly in the first quarter of the year and increased its total assets a little more than 4 percent during that same period, the company said today.

The Medford-headquartered bank posted $4.9 million in net income, representing a year-over-year increase of 0.5 percent. Total assets increased 4.1 percent to $3.8 billion from $3.6 billion at year-end 2014.

Net interest income declined 0.6 percent to $16.4 million, compared with $16.5 million in the first quarter of 2014. Century attributed that decline to compression of the net interest margin, which decreased from 2.27 percent last year to 2.12 percent in this quarter, largely the result of a decrease in rates on earning assets.

During the first quarter, Century boosted total loans slightly, from $1.33 billion at year-end 2014 to $1.34 billion at March 31. Total deposits increased to $2.9 billion from $2.7 billion during that same period.

As loan balances remained stable and charge-offs low, the company decreased its provision for loan losses to $400,000 from $600,000 a year ago.

The company’s allowance for loan losses totaled $22.5 million or 1.68 percent of loans outstanding at the end of the first quarter, compared with $22.3 million or 1.68 percent of loans outstanding at year-end 2014, and $21.3 million or 1.68 percent of loans outstanding in the year-ago period. The increase in the allowance for loan losses was due to the increase in the size of the loan portfolio. Non-performing assets totaled $4.3 million on March 31, compared to $4.1 million at year-end 2014 and $1.6 million in the first quarter of last year.

Century Bancorp’s board of directors also declared a quarterly dividend of 12 cents per share on the company’s class A common stock and 6 cents per share on its class B common stock. Those dividends will be paid May 15 to shareholders of record on May 1.