MADISON, NJ -- American Home Products Corp (AHP) is advising women who received Norplant contraceptive implants distributed since last October to use a backup form of birth control because the company can't guarantee its effectiveness. AHP took action after routine quality testing detected lower-than-expected levels of the active ingredient in Norplant lots distributed beginning Oct. 20, 1999. As many as 22,000 women could be effected. While there has not been an unexpected rise in pregnancies in the group, the company said it would reimburse women as much as $100 to cover the cost of alternative-contraceptive costs. For more information visit www.ahp.com.