The women of the US military will still be wearing trousers, but from now on they might actually fit. In a move which highlights the changing nature of traditional gender roles, the Pentagon is road testing its first ever range of combat uniforms designed specifically for female recruits.

Seven hundred outfits are currently being tested at Fort Belvoir in Virgina. They have shorter arms than the male versions and greater breathing room around the chest and hips. Designers have also repositioned the knee pads, to compensate for the fact that women generally have shorter legs than their male counterparts.

The most important feature, in practical terms, is said to be a redesigned crotch. The camouflaged uniforms no longer boast an old-fashioned zippered fly, but are made in way that allows female soldiers to urinate without the inconvenience of having to disrobe.

Roughly 14 per cent of the members of America's armed forces are women, and 220,000 have served in Afghanistan and Iraq. The move to design uniforms which cater to their particular needs comes at a time when roles on the battlefield are being re-evaluated for the modern era.

In January, Congress recommended to President Obama that female recruits who can pass through training alongside their male counterparts should also be allowed to fully serve in battle alongside them. Previously, their roles in a theatre of war have been restricted to duties like driving trucks and piloting helicopters. For that to work, they will need more suitable equipment. At present, women soldiers are roughly 20 per cent more likely to report musculoskeletal disorders than their male counterparts, a statistic many attribute to the fact that they wear clothing and body armour designed for the male body shape.

Female aviators, meanwhile, face difficulty attending to the call of nature when wearing outfits built around the requirements of male plumbing. Many opt to avoid drinking water before flights, which makes dehydration a hazard. Pilots who get into the habit of waiting for too long to use the bathroom can also experience urinary problems.

The effort to improve their lot has largely met with approval from female combat veterans. Former Army Staff Sergeant Maria Canales told the Associated Press that during her Iraq deployment in 2005 and 2006, her body armour was painfully snug. She later upgraded to a larger suit, but that made her worry about safety.

"Thank God, nothing happened where my body was compromised," she said. "It was looser and I guess that's the disadvantage because if... we have contact, it would be easier for something to happen."