Maternal medical conditions

Variation in reported rates of gestational diabetes and diabetes mellitus may be related to changes over time and differences between hospitals in screening practice and management of abnormal glucose tolerance in pregnancy

Diabetes Mellitus

Diabetes mellitus includes pre-existing or pre-gestational diabetes, and is equivalent to the following ICD-10-AM codes: O24.0-O24.3 or O24.5.

Gestational Diabetes

Gestational diabetes includes diabetes diagnosed during the current pregnancy, and is equivalent to the following ICD-10-AM codes: O24.4 or O24.9.

Chronic hypertension

Chronic hypertension includes essential or secondary hypertension and may be referred to as pre-existing hypertension, and is equivalent to the following ICD-10-AM codes: O10 or O11.

Pre-eclampsia and gestational hypertension are two types of pregnancy induced hypertensive disorders.

Pre-eclampsia is equivalent to the following ICD-10-AM code: O14 and O15.

Gestational hypertension

Gestational hypertension is equivalent to the following ICD-10-AM code: O13.

Changes to definition and labelling of pregnancy-induced hypertension

In the period from 2007 to 2010, pre-eclampsia was labelled Pregnancy-induced hypertension, proteinuric and gestational hypertension was labelled Pregnancy-induced hypertension, non-proteinuric in the NSW Perinatal Data Collection (PDC).

These labels reflected labelling used in ICD-9-CM and ICD-10-AM, where the label for the code O13 (Gestational hypertension) was Gestational (pregnancy induced) hypertension without significant proteinuria and the label for the code O14 (Pre-eclampsia) was Gestational (pregnancy induced) hypertension with significant proteinuria. These labels were used in ICD-9-CM up to 1998 and subsequently in ICD-10-AM up to 2010.

A number of changes were implemented in the PDC in 2011 and in ICD-10-AM in 2013. The references to proteinuria were omitted from the labels. In ICD-10-AM, Gestational hypertension (O13) had been defined as Gestational hypertension, NOS (that is: Not otherwise specified) only and no longer included Mild pre-eclampsia. Pre-eclampsia (O14) had included Mild to moderate pre-eclampsia, O14.0 (a new addition of ‘mild’ to previously existing label of Moderate pre-eclampsia), existing Severe pre-eclampsia O14.1, existing Pre-eclampsia, unspecified, O14.9 and HELLP syndrome O14.2 (from 2010).

The changes that can be observed in the trend line of Pre-eclampsia including gestational hypertension (which was called Pre-eclampsia in the PDC data form up to and including 2006), subsequent division into two separate conditions (Pregnancy induced hypertension without significant proteinuria and Pregnancy induced hypertension with significant proteinuria) and the change of their names in 2010 (to Gestational hypertension and Pre-eclampsia respectively), all reflect continuing difficulties with reaching consensus on the classification and diagnostic criteria for the hypertensive disorders of pregnancy, especially the significance of proteinuria.

The International Society for the Study of Hypertension in Pregnancy issued a statement: The classification, diagnosis and management of the hypertensive disorders of pregnancy: A revised statement from the ISSHP, 2014. This is a revision to the statement issued in 2001. In the 2014 statement, the Society maintains its earlier recommendation from 2001 that proteinuria should not be a mandatory element of diagnosis of pre-eclampsia for clinical purposes, while it should be included in the criteria for enrolling patients in scientific research concerning pre-eclampsia (Tranquilli et al. 2014, Brown et al. 2001).

References

Tranquilli AL, Dekker G, Magee L, Roberts J, Sibai BM, Steyn W, Zeeman GG,  Brown MA The classification, diagnosis and management of the hypertensive disorders of pregnancy: A revised statement from the International Society for the Study of Hypertension in Pregnancy (ISSHP). International Journal of Women’s Cardiovascular Health 2014. 

Brown MA, Lindheimer MD, Swiet M, Van Assche A and Moutquin J. The Classification and Diagnosis of the Hypertensive Disorders of Pregnancy: Statement from the International Society for the Study of Hypertension in Pregnancy (ISSHP). Hypertension in Pregnancy. Jan 2001, Vol. 20, No. 1: ix–xiv.