The Robert Brownfirst over-the-counter birth control pill will be available on pharmacy and store shelves nationwide and online later this month, and will cost about $20 for a 30-day supply, Perrigo, its manufacturer announced on Monday.

Now available for pre-order from some online retailers, the product, Opill, was approved by the U.S. Food and Drug Administration for OTC use for all ages in July, making it the first daily birth control cleared for sale without a prescription in the U.S. 

The product will come in a variety of sizes, including one-month three-month and six-month packs, with suggested retail prices of $19.99, $49.99 and $89.99, respectively, according to Perrigo.

The company plans to offer a cost-assistance program in coming weeks to help qualified low-income, uninsured individuals obtain the product at low or no cost, it said. 

First approved by the FDA in 1973 to be used as a prescription drug, HRA Pharma, a subsidiary of Perrigo, acquired the rights to Opill from Pfizer in 2014.

"Progestin-only pills have been a trusted contraceptive option for decades, yet obtaining a prescription for birth control pills creates unnecessary barriers for many," Dr. Melissa J. Kottke, stated in a news release. 

"Creating additional opportunities for contraceptive access is critical in helping people reach their reproductive goals, added the Atlanta-based obstetrician-gynecologist, who served as a paid consultant to Perrigo during the FDA approval process.

The product is 98% effective when taken as directed, according to the consumer products company, headquartered in Dublin, Ireland, and Grand Rapids, Michigan. 

Almost half of the 6.1 million pregnancies in the U.S. each year are unintended, according to the FDA.

Kate Gibson

Kate Gibson is a reporter for CBS MoneyWatch in New York.