ICD-10-CM > O00-O9A > O30-O48 > O31 > O31.3 > O31.31 O31.31 Continuing pregnancy after elective fetal reduction of one fetus or more, first trimester Non-Billable/Non-Specific Codes O31.31X0..., not applicable or unspecifiedO31.31X1..., fetus 1O31.31X2..., fetus 2O31.31X3..., fetus 3O31.31X4..., fetus 4O31.31X5..., fetus 5O31.31X9..., other fetus