IRBIL, Iraq - A girl strapped with explosives approaches an Iraqi army captain, who dies in the suicide blast. A woman posing as a mother-to-be to disguise a bulging bomb belt strikes a wedding procession as part of a coordinated attack that kills nearly three dozen people.

The attacks last month were among the latest blows by female suicide bombers - and further evidence of shifting insurgent tactics amid an overall drop in bloodshed around Iraq.

U.S. military figures show the number of female suicide attacks has risen from eight in 2007 to at least 16 this year, not including a suicide bombing yesterday near Ramadi that Iraqi police say they believe was carried out by a woman. That compares with a total of four in 2005 and 2006, according to the military.

Some female bombers appear motivated by revenge, such as the woman who killed 15 in Diyala province Dec. 7. She was a former member of Saddam Hussein's Baath party whose two sons joined al-Qaeda in Iraq and were killed by Iraqi security forces.

But activists and U.S. commanders also say al-Qaeda in Iraq is increasingly seeking to exploit women who cannot deal with the grief of losing husbands, children and others to the violence.

"Al-Qaeda is preying on those who don't have jobs, who don't have education, and who are feeling despair," Maj. Gen. Mark Hertling said on the sidelines of a conference this week on women's issues.

The use of women as suicide bombers is a relatively new phenomenon in Iraq, although it has been used by militants elsewhere, particularly in Sri Lanka.

Farhana Ali, a terrorism expert with the RAND Corp. who has studied the issue extensively, said al-Qaeda in Iraq's efforts to recruit women reflected its desperation after recent crackdowns.

"Al-Qaeda and insurgents are now desperate and want to ensure that their cause [and] organization stays alive," she said. "Women's participation in violence keeps the cause alive for many reasons. Women, like men, also share similar grievances, especially women who have suffered a loss."

The rise in female suicide bombings comes as the U.S. military says violence is down to its lowest levels in more than four years. The reasons include last year's U.S. troop buildup, a Sunni revolt against al-Qaeda in Iraq, and a cease-fire by the radical Shiite cleric Muqtada al-Sadr.

American commanders say al-Qaeda in Iraq is seeking out women and children to evade stepped-up security and checkpoints.

Iraqi women often are allowed to pass through male-guarded checkpoints without being searched, and they traditionally wear flowing black robes that make it easier to hide explosives belts.

Hertling, who commands U.S. forces in northern Iraq, said women carried out five of seven suicide attacks in the last three months in Diyala.

They included a double bombing May 17 in which a woman blew herself up outside an office for a U.S.-allied Sunni group and a female suicide car bomber killed one person in an attack on a police patrol.

He said at least two recent suicide bombers were the wives of an al-Qaeda in Iraq leader who was killed in U.S. military operations, although he would not give details.