OTTAWA--The maker of the birth-control pill Alysena 28 has issued an urgent recall Monday after it was discovered that one lot of the contraceptive may have been incorrectly packaged with only two weeks of drug-containing tablets instead of three.

Women taking the incorrectly packaged pill would not receive the proper amount of contraceptive, raising the possibility of an unplanned pregnancy.

In a recall notice distributed by Health Canada, Apotex Inc. said the product's 28-day blister packs should include 21 active birth-control pills plus seven placebo tablets that contain no drug.

Apotex said blister packs in the affected lot — LF01899A — may instead contain 14 placebo pills and 14 active contraceptive tablets.

Alysena 28 is sold in British Columbia, New Brunswick, Newfoundland and Labrador, Nova Scotia, Ontario, P.E.I. and Quebec.