TABLE 1—

Definition of Maternal Morbidities and Risk Behaviors Using ICD-9-CM Codes: California; 1999, 2002, and 2005

Morbidity or Risk Behavior	ICD-9-CM Discharge Codes	Sensitivity, %	Specificity, %
Hypertension	401–405, 642
Chronic hypertension	401–405, 642.0, 642.1, 642.2	44–86	97–100
Pregnancy-related hypertension	642.3, 642.4, 642.5, 642.6, 642.7	49–88	100
Diabetes	250, 648.0, 648.8
Pregestational diabetes	250, 648.0	75–100	99–100
Gestational diabetes	648.8	69–96	100
Asthma	493	12–42	98
Thyroid disordersa	240–246, 648.1	10–97	100
Obesityb	278	11
Mental health conditionsc	290–302, 317–319, 648.4, V11
Substance abused	304, 305.2–305.9, 648.3, 655.5
Tobacco usee	305.1, V15.82	15–66	99

Note. ICD-9-CM = International Classification of Diseases, Ninth Revision, Clinical Modification.²⁶

^aIncludes hyperthyroid disorder (244.9) and hypothyroid disorder (240.9).

^bObesity was defined as a body mass index (weight in kilograms divided by the square of height in meters) of ≥ 30.

^cMental health conditions include dementias, alcohol-induced mental disorders, drug-induced mental disorders, transient and persistent mental disorders resulting from conditions classified elsewhere, schizophrenic disorders, episodic mood disorders, delusional disorders, psychoses, pervasive developmental disorders, anxiety, dissociative and somatoform disorders, personality disorders, sexual and gender identity disorders, mild intellectual disabilities, other specified intellectual disabilities, mental disorders complicating pregnancy and childbirth or the puerperium, and personal history of mental disorder.

^dSubstance abuse includes drug abuse; nondependent cannabis abuse; nondependent hallucinogen abuse; nondependent sedative, hypnotic, or anxiolytic abuse; nondependent opioid abuse; nondependent cocaine abuse; nondependent amphetamine or related acting symphathomimetic abuse; nondependent antidepressant type abuse; nondependent other mixed or unspecified drug abuse; drug dependence complicating pregnancy and childbirth or the puerperium; and suspected damage to fetus from drugs affecting management of mother.

^eTobacco use includes tobacco use disorder and personal history of tobacco use.