August 1 marks the day when a key provision of President Obama’s health care reform law goes into effect: private insurance companies now must provide contraception and many women’s preventive services for free.

But because insurance in general can be complicated, there are some things you’ll need to know.

The law requires new insurance plans to fully cover women’s preventive care, including free birth control, yearly wellness visits, breastfeeding counseling and equipment, and screening for gestational diabetes, domestic abuse, HPV, sexually transmitted infections and HIV.

That said, the new requirement doesn’t apply to health plans in effect before March of 2010 — and that includes most employer-sponsored plans (the majority of which already cover contraception). But starting now, new health plans must offer the expanded wellness coverage without a co-pay.

If you have insurance, check its annual start date. If, for example, your plan started on July 1 of this year, you may be responsible for co-pays until your new plan begins on July 1 of next year, although some insurance companies have said they will implement the law early. And of course religious institutions that offer health insurance to employees may choose not to offer free birth control.

There are other stipulations, rules and exemptions (Jezebel did a nice job of breaking them down), but overall, the Obama administration estimates that 47 million women will now be able to get preventive services that they couldn’t before the new law went into effect.

[WebMD]