Amazon is limiting how many emergency contraceptives consumers can buy, joining other retailers who put in place similar caps following the Supreme Court decision overruling Roe v. Wade.

Amazon's limit, which temporarily caps purchase of the contraceptives at three units per week, went into effect on Monday, a spokesperson for the e-commerce giant confirmed to The Associated Press. The company did not share further details on what emergency contraceptive products were limited for purchase, but a listing showed the cap applied to Plan B, the popular "morning after" pill.

A similar policy went into effect Monday at the drugstore chain Rite Aid, which has limited the purchase of Plan B pills to three units per customer due to increased demand, a company spokesperson said. The limit applies to both in-store and online purchases.

Emergency contraception is different from abortion pills used to end a pregnancy. Plan B, which can be obtained without a prescription, contains a concentrated dose of the same drug found in many regular birth control pills. If a woman takes Plan B within 72 hours of unprotected sex, she can lower the risk of pregnancy significantly.

Emergency contraception has been attacked by some abortion foes who believe life begins when an egg is fertilized. The federally approved label says it may prevent a fertilized egg from attaching to the womb. But researchers with the American College of Obstetricians and Gynecologists have said its unlikely to have that effect.

A large Missouri hospital chain briefly stopped providing Plan B due to confusion over whether the state's abortion ban could put doctors at risk of criminal charges for providing it. St. Luke's Health Kansas City said Wednesday, however, that it would resume offering the medication.

Retailers limiting purchases is standard practice that helps retailers prevent stockpiling and reselling at higher prices.

"Retailers are being cautious. They are trying to manage it," said Neil Saunders, managing director at GlobalData Retail. "But I don't think there are chronic shortages."

Walmart, Amazon's top competitor, has capped online purchases of Plan B to 10 units, though it's unclear when the purchase limit began. The retailer doesn't have in-store limits at this time, but managers may make changes to help ensure availability based on the demand.

"Many of our products have online purchase limits in place," a Walmart spokesperson said. "During times of fluctuating demand, these limits may change."

Meanwhile, CVS Health said it removed its own caps on emergency contraceptives after it installed a temporary limit following Friday's high court ruling. The company said it had been seeking to preserve access to the products following a "sharp increase" in sales, which have since returned to normal levels.

"We continue to have ample supply of emergency contraceptives to meet customer needs," CVS Health spokesman Matthew Blanchette said.

The pharmacy chain Walgreens is still able to meet demand for in-store purchases and curbside pickup of over-the-counter emergency contraception pills. But spokeswoman Emily Mekstan said the company is restocking its ship-to-home business, which saw a jump in demand. CVS Health and Walgreens are the two biggest U.S. drugstore chains. They run around 19,000 locations combined.

Spokespeople for Target and Kroger said they didn't have anything to share on potential limits on contraceptive purchases.

Haleluya Hadero reports for the Associated Press. AP staff writers Anne D'Innocenzio in New York and Tom Murphy in Indianapolis contributed to this report.

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