Definition of maternal chronic diseases

A woman was considered as having diabetes mellitus if she had either at least one diagnosis of diabetes mellitus (ICD-9 codes 250 and 648.0) or a prescribed antidiabetic drug dispensed at least one year before conception, or at least one diagnosis of diabetes mellitus or gestational diabetes (ICD-9 code 648.8) or a prescription dispensed during pregnancy and a diagnosis of diabetes mellitus between four and 12 months after pregnancy. A woman was considered as having chronic hypertension if she had either at least one diagnosis of chronic hypertension (ICD-9 codes 401 to 405, 642.0, 642.1, and 642.7) or a prescription for an anti-hypertensive drug dispensed at most one year before conception or at least a diagnosis of chronic hypertension or a prescription for an antihypertensive drug dispensed during the first 20 weeks of gestation, or at least one diagnosis of chronic hypertension or of pregnancy induced hypertension or a prescription for an antihypertensive drug dispensed after 21 weeks� gestation followed by a diagnosis of chronic hypertension between four and 12 months after pregnancy.