No link between TNF-alpha therapy and preterm delivery, SGA

Last Updated: 2018-03-30

By Anne Harding

NEW YORK (Reuters Health) - Women with autoimmune disease who use biologics before and during pregnancy do not appear to be at increased risk of preterm delivery or having a small-for-gestational-age (SGA) infant, according to a new population-based study.

"These results are fairly reassuring that problems like preterm delivery and small for gestational age aren't huge concerns when we're looking at balancing risks and benefits," lead author Nicole W. Tsao of Arthritis Research Canada in Richmond told Reuters Health by phone.

Tumor necrosis factor (TNF)-alpha is involved in the abnormal immune response that occurs in autoimmune disease, and also plays a role in pregnancy and delivery, Tsao and her colleagues note in the Annals of the Rheumatic Diseases, online March 1. At the same time, women with autoimmune disease are at increased risk of poor pregnancy outcomes, especially if their illness is poorly controlled.

Tsao and her team reviewed data on 6,218 women with autoimmune disease who had a total of 8,607 pregnancies in 2002-2012. There were 109 women exposed to biologics three months before or during pregnancy, who had 120 pregnancies in all. Each exposed pregnancy was matched to five unexposed pregnancies using high-dimensional propensity scores (HDPS).

Most biologics-exposed women had rheumatoid arthritis or inflammatory bowel disease, and more than 90% were on infliximab, etanercept or adalimumab.

Eighteen percent of the infants in the exposed group were born preterm, versus 16% of the unexposed infants. Rates of SGA were 9% and 10%, respectively.

The odds ratios associated with biologic exposure after HDPS matching were 1.13 (95% confidence interval, 0.67 to 1.90) for preterm delivery and 0.91 (95% CI, 0.46 to 1.78) for SGA.

While the study did include some women who were on non-TNF-alpha biologics, the numbers were too small to conduct a separate safety analysis on these medications, Tsao said.

Dr. Christina Chambers, a professor of pediatrics at the University of California San Diego, also called the findings "reassuring." Dr. Chambers is president-elect of Mother to Baby (mothertobaby.org), which provides free counseling to women in the United States and Canada on the safety of medications in pregnancy and during lactation.

"They showed, and we've shown it as well, that although most of these diseases are associated with an increased risk of preterm delivery and small for gestational age, treatment with a biologic medicine in itself doesn't seem to increase that risk," she told Reuters Health by phone.

Physicians struggle with whether to keep patients on biologics during pregnancy, Dr. Chambers added, and perception of the risks and benefits can vary by specialty. For example, she noted, gastroenterologists often prefer to keep their patients with inflammatory bowel disease on biologics during pregnancy given the risk of a flare-up.

Use of biologics is increasingly common, and the drugs are being prescribed for a wider variety of indications, Dr. Chambers noted. "The whole idea of understanding the safety of these medications in pregnancy and the converse, if you don't use them what's the downside of that, what are the alternatives, that I think is the really important issue that's only going to get more important going into the future."

The study was funded by The Arthritis Society.

SOURCE: http://bit.ly/2pdwWI3

Ann Rheum Dis 2018.