Certolizumab (Cimzia) During Pregnancy: Placental Transfer

What does the evidence say about certolizumab pegol during pregnancy?

1. MotherToBaby reports more than 2,000 certolizumab-exposed pregnancies without a higher rate of birth differences in the available data, while noting that active autoimmune disease itself can affect pregnancy outcomes. 1
2. In CRIB, 13 of 14 evaluable infants had no quantifiable certolizumab in plasma at birth and one had 0.042 micrograms per milliliter; no infant had a quantifiable level at weeks four or eight. 2
3. MotherToBaby reports that studies have not found a higher miscarriage rate with certolizumab. This clinical-outcome evidence is separate from the small CRIB study of drug transfer and does not rule out every individual risk. 1
4. CRADLE found 77 of 137 breast-milk samples had no measurable certolizumab and estimated a median relative infant dose of 0.15%; it measured milk exposure, not long-term infant outcomes. 3
5. CHERISH modeled maternal certolizumab concentrations during pregnancy and found substantial overlap with simulated nonpregnant concentrations, supporting established maternal regimens; it did not measure fetal concentrations, placental transfer, or birth outcomes. 4

Is certolizumab pegol safe in each trimester?

• First trimester. More than 2,000 reported pregnancy exposures have not shown a higher overall rate of birth differences, but these observational data cannot rule out uncommon outcomes or fully separate medicine effects from the underlying inflammatory condition.
• Second trimester. Keeping inflammatory disease controlled remains part of the risk-benefit decision. Certolizumab lacks the Fc region used by intact IgG antibodies for active placental transfer, but that structural distinction does not replace clinical monitoring.
• Third trimester. CRIB directly measured maternal, cord, and infant concentrations after late-pregnancy dosing and found minimal transfer. Its 14 evaluable infant samples were too few to establish uncommon birth or long-term developmental outcomes.