TNF Inhibitor Use in Pregnancy & Breastfeeding
When I first started thinking about becoming a mom after being diagnosed with rheumatoid arthritis, one of the biggest challenges was figuring out my options for keeping my RA under control while pregnant and breastfeeding. Obviously, in an ideal world, I wouldn’t expose my baby to any type of medication – but having RA isn’t exactly ideal! Just a few years ago, when I first had to make this type of decision, I felt like there was very little information about the potential risks of using various medications while pregnant or breastfeeding. Luckily, studies are starting to emerge that provide some of this much-needed data! I wanted to share a few examples that focus on TNF inhibitor use during pregnancy and breastfeeding.
Tumor necrosis factor (TNF) is a chemical produced by the immune system that causes inflammation in the body. In healthy individuals, excess TNF in the blood is blocked naturally – but in individuals with RA, higher levels of TNF in the blood lead to more inflammation and persistent symptoms. TNF inhibitors are biologic medications that block the action of TNF to reduce inflammation and treat RA. Examples include Remicade (Infliximab), Enbrel (Etanercept), Humira (Adalimumab), Cimzia (Certolizumab), Simponi (Golimumab – injection), and Simponi Aria (Golimumab – infusion).
TNF inhibitors are increasingly being used to control RA during pregnancy
(I used one myself during my second pregnancy). However, most of these medications are actively transported across the placenta, meaning they reach higher fetal than maternal blood levels. Because TNF inhibitors purposefully suppress the immune system, a study was performed to see if babies exposed to TNF inhibitors in utero had a higher risk of developing serious infections once born compared to the general population. It was the largest study to date to address this important issue. Dr. Evelyne Vinet presented the results at the 2016 American College of Rheumatology (ACR) Annual Meeting session on Reproductive Issues in Rheumatic Disorders.
The results of the large database study showed that prenatal exposure to TNF inhibitors does not significantly increase the risk of a serious infection in infants born to women taking the medication for RA. There was, however, a threefold increased risk of serious infection in infants exposed in utero to infliximab, compared to the other types of TNF inhibitors. Dr. Vinet noted that infliximab is unique among the TNF inhibitors in that it concentrates in cord blood. Thus, it is possible that the risk may be different with each type of medication.
At the same 2016 ACR Session, Dr. Megan Clowse presented the results of the first sponsored study of the potential transfer of a TNF inhibitor into breast milk. This study focused on Cimzia (certolizumab), and found that there is minimal to no transfer of the medication from plasma to breast milk. Despite using highly sensitive testing methods, the medication was completely undetectable in 56% of the milk samples. When it was detectable, concentrations of the drug were less than 1% of the concentration of a regular therapeutic dose (less than 10% is considered unlikely to be of clinical concern). Additionally, Dr. Clowse noted that any amount of medication that did find its way into the breast milk would likely be degraded by the baby’s digestive system – which is why people with RA cannot take this medication orally.
Thus, the findings of this study imply that Cimzia is compatible with breastfeeding.
Of course, these studies are not definitive – more research is certainly needed in these areas. But the fact that this research is starting to happen is very exciting! It will be wonderful for women who depend on these medications to have more data and more options when making difficult decisions about pregnancy and breastfeeding.