The remains of the woman and unborn child were found in a tomb with three other sacrificed women and several sacrificial llamas, lead archaeologist Carlos Wester La Torre told The Associated Press.
In all, Wester La Torre's team reported finding the remains of seven women in two tombs at the Chotuna Chornancap archaeological site, each showing signs of having been cut at the throat.
The sacrifice of a pregnant woman "is very unusual" in the pre-Inca world, said respected Peruvian archaeologist Walter Alva, who was not involved in the discovery.
"The concept of fertility was well respected, so this could represent a sacrifice for a very important religious event," he said Wednesday.
Chotuna Chornancap is a sacred site of the Lambayeque culture, which flourished in northern Peru between 800 and 1350 A.D. - More