MOUNTAIN VIEW, Calif. (AP) Conceptus Inc., which develops the Essure permanent birth control procedure, said Tuesday that its first-quarter loss widened on a decline in revenue.

The results sent share plummeting in after-hours trading.

Conceptus lost $2.9 million, or 9 cents per share, compared with a loss of $2.4 million, or 8 cents per share, during the same period a year prior. Revenue fell 21 percent to $21.4 million from $27 million.

Analysts surveyed by FactSet expected a loss of 5 cents per share on $32.4 million in revenue.

The company said the unemployment situation and the loss of insurance coverage by some people partly affected the ability of consumers to pay for Essure.

"Macroeconomic pressures, challenging insurance trends, competitive trialing and our planned strategic focus were the primary factors that impacted our sales this quarter," said President and CEO Mark Sieczkarek, in a statement.

Looking ahead, the company expects sales between $135 million and $150 million in 2011. Analysts expect $142.6 million in sales.

Shares of Conceptus fell $2.09, or 13.9 percent, to $13 in after-hours trading, after gaining 18 cents to close at $15.09 during the regular trading session.