Mississippi House and Senate members must work out differences on a bill to ban abortion after 20 weeks' gestation.
The Senate passed House Bill 1400 unanimously Tuesday, changing the bill to require more work.
Senators rejected an exemption for terminating pregnancies that occurred through rape or incest.
Twenty weeks is halfway through a full-term pregnancy of 40 weeks. Exceptions to the 20-week ban would be made to prevent permanent physical damage or death of a pregnant woman, or in cases of several fetal abnormalities.
Health Department statistics show 2,176 abortions in Mississippi in 2012. Two were reported at 21 weeks or later, and 382 were listed as unknown gestational age.
Diane Derzis owns Mississippi's only abortion clinic and says abortions stop there after 16 weeks.