prenatal lethality MP:0002080 survival: prenatal lethality MGI:2173525 MP:0001707 death anytime between fertilization and birth (Mus: approximately E18.5) embryonic lethality MPheno.ontology MP:0001645 Note that the name of this term has previously been embryonic lethality. In many species, the terms prenatal lethality and embryonic lethality are used interchangeably. However, this is not technically correct and we have modified this ontology to define the prenatal period to include the embryonic stages distinctly from the fetal stages. The names embryonic lethality and embryonic death have been retained as a narrow synonyms to aid in searching for those species that may use these terms as synonyms. survival: embryonic lethality embryonic death antenatal lethality preweaning lethality