Wait a minute, I just saw numbers in the 60's
Each year, public funding for family planning prevents about 1.94 million unintended pregnancies, including almost 400,000 teen pregnancies. Preventing these pregnancies results in 860,000 fewer unintended births, 810,000 fewer abortions and 270,000 fewer miscarriages. More than nine in 10 women receiving publicly-funded family planning services would be eligible for Medicaid-funded prenatal, delivery, and postpartum care services upon pregnancy. Avoiding the significant costs associated with these unintended births saves taxpayers $4 for every $1 spent on family planning.
Evidence that expanding access to contraception through Medicaid is unequivocal: Increased access saves taxpayer money.
During the 1990s, HHS states:
...many states implemented Medicaid Section 1115 Family Planning Demonstrations. An independent evaluation of the experience of six of these states found that all six Demonstrations yielded savings, with annual state savings ranging between $1.3 million in New Mexico and nearly $30 million in Arkansas.
As of August 1, 2010, 27 states, including States like Pennsylvania, Texas, Florida, and Virginia had expanded Medicaid eligibility for family planning services under waivers that stipulated that these expansions be budget neutral. Based on this experience, the Congressional Budget Office has estimated that expanding family planning to all States would save $400 million over 10 years.
Why would insurance companies provide contraception without a co-pay to their female employees? The answers are clear.
The Cost of Contraception in Insurance Plans: What the Data Say | RH Reality Check
http://www.cluw.org/PDF/ContraceptiveCoverageSavesMoney.pdf
http://www.nwlc.org/sites/default/files/pdfs/contraceptive_coverage_saves_money_fact_sheet.pdf
Disease Management Care Blog: White House: "Covering contraception is cost neutral since it saves money" - The Birth Control Controversy and Using Today's Costs for Tomorrow's Savings
The Cost of Covering Contraceptives through Health Insurance: ASPE Issue Brief
More sources, Facts, and up to date numbers.