The Federal Home Loan Bank of Boston turned a $46.8 million profit in the first quarter compared to $23.1 million in the same period a year ago.

Its fourth quarter profit was $64.7 million.

Total investments declined 13 percent to $18.6 billion from $21.4 billion as of Dec. 31. The bank said the decrease was the result of a lack of demand for investments to satisfy liquidity requirements.

The FHLB held $3.2 billion in loans in its portfolio at the end of the quarter, flat with a year ago and a slight increase over the fourth quarter.

The FHLB earned $4.4 million on net prepayment fees from advances and investments during the quarter. The increased profitability led the FHLB to make a $5.2 million contribution to its affordable housing program for the quarter.

Credit-related and "other-than-temporary" charges on certain private label mortgage-backed securities were $3 million during the quarter, $27.6 million less than the $30.6 million recorded in the first quarter of 2011.

Net interest income for the quarter was $69.5 million compared to $66.9 million a year ago and $82 million in the fourth quarter. The bank also reduced its allowance for credit losses on mortgage loans by $1.2 million due to a decline in delinquencies in its portfolio.

Net interest margin was 0.56 percent compared to 0.49 percent a year ago and 0.65 percent in the fourth quarter.

Average earning assets were $48.7 billion compared to $55.3 billion a year prior.

Return on average assets was 0.38 percent compared to 0.17 percent a year ago and 0.51 percent in the previous quarter.