Germany drug company Bayer AG says it intends to buy California-based Conceptus to expand its birth control offerings.

Bayer said Monday it would launch a public offer to pay $31.00 per share for all the stock in Conceptus, Inc. That means Bayer would pay $1.1 billion.

Conceptus makes Essure, an irreversible birth control method in which metal and polyester coils are inserted to block a woman's fallopian tubes. The procedure can be done in 10 minutes a doctor's office.

Conceptus CEO D. Keith Grossman was quoted in a Bayer statement as saying Essure "will benefit in new markets from Bayer's global presence."

The deal is subject to approval by antitrust authorities and could be completed by midyear.

Conceptus is based in Mountain View, California and employs about 300 people.