Women who take biologics for autoimmune disorders either three months before or during their pregnancy are not at higher risk of a preterm birth or having a smaller than normal child, a Canadian study reports.
It applied to a range of autoimmune disorders, including inflammatory bowel disease (IBD).
Researchers published their study in the journal Annals of the Rheumatic Diseases. The title is “Risk of preterm delivery and small-for-gestational age births in women with autoimmune disease using biologics before or during pregnancy: a populationbased cohort study.”
Autoimmune disorders are characterized by dysfunction of pro-inflammatory molecules called cytokines and chemokines, which regulate immune activity. Tumor necrosis factor (TNF)-alpha is one of the key cytokines in this process.
Abnormally high levels of TNF-alpha have been associated with pregnancy complications, including preterm births, slower fetus growth, and miscarriages. Overall, the evidence suggests that higher autoimmune disease activity at conception or during pregnancy may increase the risk of a problem in a mother who gives birth or her newborn.
Pregnant women with autoimmune diseases have been increasingly using medications that target crucial inflammatory cytokines — including TNF-alpha — that could affect births.
But studies on whether these treatments can cause birth problems have used small samples and have had control-group design limitations. In addition, most did not adjust for differences in participants’ diseases before the research started.
This prompted a Canadian team to look at whether biologics that women with autoimmune diseases take before or during their pregnancy can lead to birth problems. They focused on the risk of preterm births and delivering newborns of smaller than normal stature — conditions associated with infant disease and death.
The team combed through a healthcare database in British Columbia for patients for the study. They found 6,218 women with an autoimmune disease who became pregnant between Jan. 1, 2002, and Dec. 31, 2012.
Doctors prescribed at least one biologic three months before or during pregnancy to 109 women and no biologic to 584. The most prescribed medications were the TNF-alpha inhibitors Remicade (infliximab, Janssen Immunology), Enbrel (etanercept, Amgen) and Humira (adalimumab, AbbVie).
The key finding was that biologics did not change the women’s risk of having a preterm birth or a smaller than normal newborn. Since TNF-alpha inhibitors accounted for 94 percent of the biologics used, the results apply mostly to this type of medication, the researchers wrote.
Another finding was that a fetus’s mean age at delivery was 38 weeks, regardless of whether the mother was taking an anti-TNF-alpha inhibitor.
Among the study’s strengths, the researchers said, was the high quality and broad coverage of the population-based databases they used. This allowed the team to match the timing of medications with pregnancy milestones.
Another strength was using newborns’ size at birth as an outcome measure. Still another was having controls who had not taken biologics for comparison.
“Our findings suggest that biologics may be a safe treatment option for women with certain autoimmune diseases who, as previous research suggest, are at higher risk of adverse pregnancy outcomes due to their disease,” the team wrote.
“Our study represents an important contribution to the accumulation of evidence on the safety of the use of biologics in pregnant women, which may lead to increased prescriber comfort and patient acceptance, decreased uncertainty and improved maternal and neonatal [birth] outcomes in this population,” they added.