Background/Purpose

It is believed that pregnant women with SLE face an increased risk of stillbirths, although there are few precise or recent estimates of the magnitude of the effect. As well, no one to date has investigated the causes of stillbirths in SLE pregnancy. Using the “Offspring of Systemic Lupus Erythematous Registry (OSLER)”, we examined stillbirths and the cause of their death in SLE mothers versus those without SLE.

Methods:

OSLER is a large population-based cohort, which includes all women who had one or more hospitalizations for delivery after SLE diagnosis, identified through Quebec’s healthcare databases (1989-2009). OSLER also includes a randomly selected control group of healthy women, matched at least 4:1 for age and year of delivery. We identified stillbirths (defined as intrauterine deaths occurring at or after 20 weeks of gestational age) from SLE mothers and their matched controls and ascertained the cause of death as indicated on the death certificate. We performed a multivariate logistic regression analysis, using generalized estimating equations, to estimate the risk of stillbirths in SLE offspring versus controls, adjusting for maternal education, comorbidities (i.e. hypertension, diabetes, asthma, depression), and multiple births.

Results:

509 women with SLE had 729 births, including 9 stillbirths (1.4%), while 5829 matched controls had 8541 births including 47 stillbirths (0.6%). Compared to controls, women with SLE had an increased risk of having a stillbirth (adjusted OR 2.16, 95% CI 1.05, 4.44). Among women having a stillbirth, median maternal age was identical for both SLE and control mothers [respectively 31.0 years (IQR 29.0, 32.0) and 31.0 years (IQR 26.5, 30.5)]. There was a trend for more female stillbirths born to women with SLE (6 of nine stillbirths were female) compared to controls (22/47) (OR 2.27, 95% CI 0.54, 9.41). In addition, stillbirths in SLE mothers occurred at a younger median gestational age compared to controls [29 weeks (IQR 28, 31) versus 35 weeks (IQR 27, 38)].

Causes of death in SLE and control stillbirths are illustrated in Table 1. We observed a trend for higher risk in SLE mothers versus controls for stillbirths due to maternal hypertensive disorders and placental abruption [respectively OR 6.43 (95% CI 0.8, 53.3) and OR 4.19 (95% CI 0.59, 29.72)].

Conclusion:

Compared to women from the general population, women with SLE appear to have an increased risk of stillbirths, although it must be emphasized that most pregnancies in SLE are not complicated by this event. Stillbirths in mothers with SLE might be more often caused by maternal hypertensive disorders and placental abruption compared to stillbirths in mothers without SLE.

Table 1. Causes of death among SLE and control stillbirths

^aReference for classification of causes of death: Stillbirth Collaborative Research Network Writing Group. Causes of death among stillbirths. JAMA. 2011 Dec 14;306(22):2459-68.