The primary purpose is to assess whether there is transfer of Certolizumab Pegol (CZP) from pregnant women receiving treatment with Cimzia® across the placenta to infants by evaluating the concentration of CZP in the plasma of infants at birth.

Inclusion Criteria:

• An IRB/IEC approved written Informed Consent form for the maternal subject and her infant(s) is signed and dated by the subject. Where applicable, the written Informed Consent form with respect to the infant(s) is also signed and dated by the holder of parental rights as designated by the maternal subject
• Subject is considered reliable and capable of adhering to the protocol and visit schedule according to the judgment of the Investigator
• Subject is female ≥18 years at the time of informed consent
• Subject is ≥30 weeks pregnant with a singleton or twins at the time of informed consent
• Subject is being treated with Certolizumab Pegol (CZP) per the current approved prescribing Information
• Subject started or decided to continue treatment with CZP independently from and prior to participating in this study and in accordance with the treating physician
• Subject expects to receive CZP until at least 35 days prior to expected delivery (date of injection counted as Day 1)

Additional criteria to be confirmed prior to first sample from infant at Visit 2 (delivery/birth):

• Subject delivers a live born infant(s) at or near term (≥34 weeks gestation )
• Subject received CZP within 35 days before delivery (date of injection counted as Day 1)
• Subject has not received contraindicated medication

Exclusion Criteria:

• Subject has participated in a study of an investigational medicinal product (IMP) or medical device within the previous 30 days or 5 half-lives (whichever is longer) prior to Screening or is currently participating in another study of an IMP or medical device - unless the study is UCB UP0016 [NCT02154425] or a registry study
• Subject has any obstetrical or psychiatric condition, or she or her infant(s) has any medical condition that, in the opinion of the Investigator, could jeopardize or would compromise the subject's ability to participate in this study or the outcome of the pregnancy
• Subject has history of chronic alcohol abuse or drug abuse during pregnancy
• Subject has any pregnancy-related clinically significant abnormality noted on obstetric ultrasound, or other imaging assessment, or the subject has significant laboratory abnormalities during her pregnancy, as judged by the Investigator
• Subject is taking or has taken any medication with strong positive evidence of a human fetal risk of teratogenicity (e.g., methotrexate or leflunomide) during pregnancy
• Subject has evidence of a condition suggesting chronic or acute uteroplacental insufficiency such as intrauterine growth restriction, severe maternal hypertensive disorders of pregnancy, or abruption
• Subject has a documented history of primary or secondary antiphospholipid syndrome or hypercoagulable state
• Subject has received treatment with any biological therapeutic agent, including anti-TNFs other than certolizumab pegol (CZP), during pregnancy
• Subject has previously participated in this study
• Subject has a positive or indeterminate QuantiFERON®-TB GOLD In Tube test at Screening. In case of indeterminate result, a retest is allowed if time permits; 2 results of indeterminate require exclusion of the subject
• Subject with known tuberculosis (TB) infection, at high risk of acquiring TB infection, or latent TB infection (LTB). If tested within the 6 months prior to Screening and the test was negative for TB, and there is no change in the subject's clinical status, nor social, family, or travel history, there is no need for an additional TB testing at Screening