Are there regulations that govern the rate or cost of PMI on conventional loans?

PMI is based on your credit score & down payment amount. Rate is determined based on credit score and loan program.

Sarah:PMI is calculated on your credit score and loan to value. Each mortgage insurance company sets their own rates also. Is there a particular question you regarding a PMI rate?Brenda

As stated by my colleagues it is risk based using your loan to value and credit score.

Not directly - there are regulations for the Lenders however that do restrict costs associated with your loan as reflected in your APR. PMI rates are based on risk and can be different from one MI company to the next, but they are all pretty close. This is where it benefits you to use a lender that works with multiple MI companies and can shop your premium.