For a young woman with active seropositive, erosive rheumatoid arthritis who is planning to have children, it’s essential to ask when the pregnancy is desired. When Dr. Soh asks patients this question, she is frequently surprised to learn that the timeframe the patient has in mind is over the subsequent two to three years. This may provide a window of opportunity to quickly escalate therapy, treating the disease aggressively and then allowing for a period of drug washout prior to an intended pregnancy after the disease is stable.
In a second case, a young woman with previously well-controlled axial spondyloarthritis on NSAID therapy alone became wheelchair-bound due to acute worsening of back pain in her first trimester of pregnancy. Treatments beyond acetaminophen—or paracetamol, which is used in New Zealand—ought to be strongly considered. These treatments can and should include tumor necrosis factor (TNF) alpha (α) inhibitors and secukinumab.
Biologic Therapy
Dr. Soh expanded on the topic of biologic therapy in pregnancy and its possible effects on the fetus. She explained that fetal immunoglobulin G1 (IgG1) levels reach 50% that of maternal levels between 28 and 32 weeks of gestation. These levels increase exponentially thereafter because there is maximal placental immunoglobulin transfer from mother to baby in the final four weeks before delivery.2
Cord blood levels of biologic medications have been studied and depend on several factors:
- The point in gestation when the drug was used (i.e., the later in pregnancy, the higher the level);
- The structure of the Fc receptor because medications lacking an Fc portion, such as certolizumab, are less efficiently transported across the placenta; and
- The half-life of the drug because the longer its half-life, the more likely there will be placental transfer.3
One reason to be cautious with biologics during pregnancy is because of the potential for the fetus to develop immunosuppression. Such immunosuppression may have practical implications, including the risk of infection for the fetus in utero or after delivery.
Dr. Soh said that, in newborns with in utero biologic medication exposure, live vaccines should be avoided for the first six to eight months of life. The only potential exceptions are rotavirus vaccination and Bacillus Calmette-Guérin vaccination in newborns not exposed to TNF inhibitors.
Dr. Soh said that one of the most joyous parts of her practice is to help a patient have a healthy & successful pregnancy as they seek to start or grow their family.
