Start Healthy, Stay Healthy Act of 2003

Start Healthy, Stay Healthy Act of 2003 - Amends title XIX (Medicaid) of the Social Security Act (SSA) to: (1) give States the option to expand coverage to certain pregnant women; (2) provide for enhanced matching funds with respect to certain pregnant women if certain conditions are met; (3) pay for such Medicaid expansion costs out of the SSA title XXI (State Child's Health Insurance) (SCHIP) allotment; and (4) no longer require that a newborn child be a member of the mother's household and that the mother remain eligible for Medicaid during the one year period after birth in order for the newborn child to continue to be eligible for Medicaid.

Amends SSA title XXI to give certain States the option of providing pregnancy-related assistance for targeted low-income pregnant women in accordance with this Act, which includes: (1) automatic enrollment for children born to women receiving such pregnancy-related assistance; (2) additional allotments for providing coverage of pregnant women; and (3) no cost-sharing for pregnancy-related services.

Provides for coordination of SCHIP with the program under SSA title V (Maternal and Child Health Services).

Increases the income eligibility for low-income children under SCHIP.

Amends SSA title XVI (Supplemental Security Income) to direct the Commissioner of Social Security to review determinations, made by State agencies in connection with applications for benefits under this title on the basis of blindness or disability, that individuals who have attained 18 years of age are blind or disabled as of a specified onset date.