What Do I Do With a Woman Who Is Pregnant and on Biologics?

Sunanda V. Kane, MD, MSPH


January 04, 2011


I have a patient with Crohn's disease who is taking infliximab. She is now pregnant. How do I manage her biologic therapy while she is pregnant?

Response from Sunanda V. Kane, MD, MSPH
Associate Professor of Medicine, Mayo Clinic, Rochester, Minnesota

This is a question I am asked on a weekly basis. Women of childbearing age may be on biologic therapy for Crohn's disease, ulcerative colitis, rheumatoid arthritis, psoriatic arthritis, and other autoimmune disorders. When treating women who are pregnant or planning to become pregnant, it is important to understand the mechanism for immunoglobin transfer so the risk for exposure of the fetus to the therapeutic monoclonal antibody in utero will be minimized.[1]

Biologics are immunoglobulins, and most cross the placenta. However, they require specific receptors to cross and, thus, do not begin to cross until the second trimester, around week 20 of pregnancy. There is a logarithmic increase in rate of immunoglobulin G (IgG) transfer over time, with maximal IgG transfer between weeks 30 and 38 of pregnancy. Thus, if a pregnant woman is on infliximab, we instruct her to time her last dose around week 30-32 of pregnancy, and then re-dose her after delivery. Women on adalimumab should be instructed to self inject their doses until around week 33-34 of pregnancy. Interestingly, there are data to suggest that certolizumab pegol, because it is a Fab fragment, does not cross the placenta at all. Thus, a woman on certolizumab pegol does not have to hold any doses throughout pregnancy.

Experts do not endorse switching biologics during pregnancy solely for the reasons mentioned above. If a pregnant woman is sick, then we continue her biologic therapy because she needs to control her disease. The above recommendations are for women who are in remission. A common mistake we see is that women stop taking their biologic in the first trimester and end up sick, requiring steroids or re-dosing of the biologic. It is during the first trimester that the risk is the lowest for transfer, and the highest for disease flare. The benefits of controlling disease outweigh the risks to the unborn baby.

There does not appear to be any increased risk for infection following caesarean section if biologics are given right after delivery, as long as there is assurance that no placenta has been retained, which could be a source for infection.

Furthermore, there are data to show that biologics do not cross into breast milk, so breastfeeding is permitted for women on most biologic therapy. Infliximab and certolizumab pegol are compatible with breastfeeding, but safety data for adalimumab are pending.[2]


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