644 Early or threatened labor convert 644 to ICD-10
644.0 Threatened premature labor convert 644.0 to ICD-10

644.00 … unspecified as to episode of care or not applicable convert 644.00 to ICD-10

644.03 … antepartum condition or complication convert 644.03 to ICD-10
644.1 Other threatened labor convert 644.1 to ICD-10

644.10 … unspecified as to episode of care or not applicable convert 644.10 to ICD-10

644.13 … antepartum condition or complication convert 644.13 to ICD-10
644.2 Early onset of delivery convert 644.2 to ICD-10

644.20 … unspecified as to episode of care or not applicable convert 644.20 to ICD-10

644.21 … delivered, with or without mention of antepartum condition convert 644.21 to ICD-10