Government safety regulators say more than 2.1 million drop-side cribs by Stork Craft are being recalled, the biggest crib recall in U.S history.

The Consumer Product Safety Commission says the recall involves 1.2 million cribs in the United States and almost 1 million in Canada, where Stork Craft is based.

Nearly 150,000 of the cribs on recall carry the Fisher-Price logo.

The agency is aware of four deaths of young children who suffocated in the cribs, which have a side that moves up and down to allow parents to lift children from the cribs more easily.

The Stork Craft cribs have had problems with their hardware, which can break, or with assembly mistakes by the crib owner.

The danger is that a child's head can get caught between the mattress and the side railing, if it separates from the crib.

This is not the first time cribs have been recalled due to such fears. Nearly 5 million cribs by several manufacturers have been recalled over the past two years, including half a million from Stork Craft earlier this year, and the CPSC has considered banning drop-down sides altogether.

"Drop-side cribs, because of the amount of hardware that's involved, because it weakens the structure of the crib itself have been involved in numerous deaths and injuries, crib failures where the side may come loose or come off," said Nancy Cowles, of the advocacy group Kids in Danger.

Stork Craft is one of the most widely purchased brand names in baby cribs, with products sold at some of the biggest retailers in the country, including Target, WalMart, Sears and Kmart.

CPSC urges parents and caregivers to immediately stop using the recalled cribs, wait for the free repair kit and avoid attempting to fix the cribs without the kit. They should find an alternative, safe sleeping environment for their baby. Consumers should contact Stork Craft to receive a free repair kit that converts the drop-side on these cribs to a fixed side.

The cribs’ drop-side plastic hardware can break or deform, or parts can become missing. In addition, the drop-side can be installed upside-down, which can result in broken or disengaged plastic parts. All of these problems can cause the drop-side to detach in one or more corners. When the drop-side detaches, it creates space between the drop-side and the crib mattress. The bodies of infants and toddlers can become entrapped in the space, which can lead to suffocation. Complete detachment of drop-sides also can lead to falls from the crib.

CPSC, Health Canada and Stork Craft are aware of 110 incidents of drop-side detachment; 67 incidents occurred in the United States and 43 in Canada. The incidents include 15 entrapments, 12 in the U.S. and three in Canada. Four of the entrapments resulted in suffocation: a 7-month-old in Gouverneur, N.Y.; a 7-month-old in New Iberia, La.; a 6-month-old in Summersville, W.Va.; and a 9-month-old in Bronx, N.Y.  Another 20 babies have fallen from their cribs.

Meanwhile, safety experts caution that cribs often stay in homes for generations. If you have one of the cribs in your basement that's been recalled in recent years, fix it or get rid of it. The full list of crib recalls is on the CPSC Web site.