NEW YORK – There is an 18% risk for congenital heart block in the subsequent pregnancy of a woman who has already had one child born with the condition, judging from registry data on outcomes of 136 such subsequent pregnancies, according to Dr. Jill P. Buyon.
In the absence of neonatal cardiac involvement, the risk for congenital heart block in the subsequent pregnancy of a woman who gave birth to a previous child with malar rash (a manifestation of neonatal lupus) is 13% if only data collected prospectively are utilized, or 18% if all data are evaluated. These risks are substantially higher than the 2% risk of congenital heart block for primigravid women with anti-SSA/Ro antibodies. The occurrence of cutaneous disease in a child born subsequent to the birth of a child with cutaneous disease is even higher, approaching 30%, Dr. Buyon said at a rheumatology meeting sponsored by New York University.
Because neonatal lupus is so uncommon, physicians have little information on which to base their advice to these concerned women. The data from the NYU Research Registry for Neonatal Lupus is a starting point for advice. To date, the NYU registry (sponsored by the U.S. National Institute of Arthritis and Musculoskeletal and Skin Diseases) has collected information on 442 families, with a total of 484 pregnancies involving neonatal lupus. Among the 484 pregnancies recorded in the registry, outcomes included 280 cases of congenital heart block, 150 cases of rash, and 38 cases involving both manifestations of neonatal lupus. The remaining 16 cases comprised 7 newborns with isolated cardiomyopathy, and another 9 with isolated hepatic/hematologic involvement.
The underlying mechanism of neonatal lupus is passively acquired autoimmunity. Although some of the mothers have symptomatic lupus or Sjögren’s syndrome, most have been asymptomatic when their unborn child developed heart block at 18-24 weeks’ gestation, or their neonate developed rash at 6 weeks post partum. Long-term follow up of the registry participants has shown that 50% of the women remain asymptomatic 4 years after the birth of their first child with either congenital heart block or cutaneous neonatal lupus. Some of the women have remained asymptomatic for up to 15-20 years of follow-up, said Dr. Buyon, professor of medicine at New York University.
Specifically, in follow-up of 51 mothers, half remained asymptomatic at a mean of 4 years. Half developed symptoms of a rheumatic disease, including four cases of Sjögren’s syndrome and five of systemic lupus erythematosus, two of which involved lupus nephritis. Mothers with anti-SSA/Ro and anti-SSB/La were twice as likely to develop an autoimmune disease as were mothers with anti-SSA/Ro only (Ann. Rheum. Dis. 2009;68:828-35).
Neonatal lupus is relatively rare and involves the fetus’s passive acquisition of autoantibodies. Affected children come to clinical attention when they either develop congenital heart block at about 20 weeks’ gestation or are born with a cutaneous rash. The mothers often are asymptomatic. The problems in their unborn or newborn child often are the first sign of their own health risks. The mother is likely to hear conflicting and confusing advice from her obstetrician and/or pediatrician.
The fetal heart block can be first, second, or third degree. Mortality in affected pregnancies is about 20%, and more than 65% of the surviving neonates required pacing. There is no equivalent adult-onset counterpart to neonatal lupus that presents as heart block. The cutaneous presentation, which involves annular or elliptical lesions on the face, scalp, trunk, and/or extremities, resembles the presentation of adult-onset systemic cutaneous lupus erythematosus. In infants, the condition is transient.
Despite being exposed to the same circulating antibodies as the fetus, the maternal heart is unaffected.
Dr. Buyon noted that she had no relevant financial relationships to disclose with regard to the study of neonatal lupus except for support from the U.S. National Institute of Arthritis and Musculoskeletal and Skin Disease, the American Heart Association, the Kirkland Center, and the Alliance for Lupus Research.