Background/Purpose: Dermatomyositis (DM) and polymyositis (PM) are autoimmune inflammatory myopathies that frequently affect females of child-bearing potential.  Small studies have indicated that active disease during pregnancy may result in intra-uterine growth restriction (IUGR) and fetal loss.  We sought to assess pregnancy outcomes of adult DM and PM patients compared with the general obstetric population using a U.S. hospitalization dataset.

Methods:

We used the Nationwide Inpatient Sample (NIS) (1993-2007) to estimate the number of obstetric hospitalizations and deliveries among women > 18 years of age with DM and PM.  Controls were from the general obstetric population hospitalized in 2007.  Pregnancy outcomes included length of hospital stay (LOS), hypertensive disorders including preeclampsia and eclampsia (HTN), premature rupture of membranes (PROM), IUGR, and cesarean delivery (C-section).  Multivariate regression analyses were performed using maternal age, race/ethnicity, antiphospholipid antibody syndrome (APLA), diabetes mellitus, renal failure, and interstitial lung disease (ILD) as covariates.

Results:

We compared 4.1 million deliveries in the general obstetric population to 459 that occurred in women with DM and 404 in women with PM.  Patients with DM and PM were slightly older than controls (28±6 years vs 27±6 years, p<.0001), and more were African American than controls (DM 30% vs 15%, p=.002; PM 46% vs 15%, p <.0001).  Renal failure and ILD were more common in both the DM and PM groups, while diabetes and APLA were more common in DM compared with controls.  In univariate analysis, LOS was significantly longer in the DM and PM groups compared with controls (3.8±3.5 in DM and 4.9±6.3 in PM vs. 2.7±2.7 days in controls, p<.0001 for both) (Table).  In multivariate analyses, DM (OR 1.6, 95%CI 0.9-2.9) and PM (OR 2.4, 95%CI 1.5-3.9) were associated with an increased odds of HTN compared with controls, though this did not reach statistical significance in the DM group.  Interestingly, DM was associated with a decreased odds of IUGR (OR 0.7, 95%CI 0.6-0.9).  There were no differences in rates of PROM or C-section in the DM or PM patients compared with controls.

Conclusion:

Our data suggest that patients with DM and PM may be at increased risk of preeclampsia and eclampsia.  We did not find an increased risk for IUGR in these patients.  Vigilant monitoring of blood pressure may be advisable in pregnant patients with DM and PM.

Table 1. Obstetric Outcomes by Diagnosis

Group	LOS (d, mean±SD)	p-value vs. control	HTN (%)	p-value vs. control	PROM (%)	p-value vs. control	IUGR (%)	p-value vs. control	C-section (%)	p-value vs. control
DM	3.8 ± 3.5	<.0001	17.3	0.0004	5.3	0.37	1.7	0.92	25	0.33
PM	4.9 ± 6.3	<.0001	24.2	<.0001	4.6	0.55	4.6	0.02	27.3	0.7
CONTROL	2.7 ± 2.7		8.8		3.6		1.8		28.9

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ACR Meeting Abstracts - https://acrabstracts.org/abstract/pregnancy-outcomes-in-adult-patients-with-dermatomyositis-and-polymyositis/