Association of higher rheumatoid arthritis disease activity during pregnancy with lower birth weight: Results of a national prospective study

Authors

  • Yaël A. de Man,

    Corresponding author
    1. Erasmus MC, University Medical Center Rotterdam, Rotterdam, The Netherlands
    • Erasmus MC, University Medical Center Rotterdam, Department of Rheumatology, Room Ee-965, PO Box 2040, 3000 CA Rotterdam, The Netherlands
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  • Johanna M. W. Hazes,

    1. Erasmus MC, University Medical Center Rotterdam, Rotterdam, The Netherlands
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    • Dr. Hazes has received consulting fees, speaking fees, and/or honoraria from Bristol-Myers Squibb (National Advisory Board), Schering-Plough (advisor on Patient Expectation Project), Roche (National Advisory Board member), UCB Pharma (member National and International Advisory Boards and symposium speaker), and Wyeth (International Summit speaker and recipient of an unrestricted grant for an investigator-initiated study) (less than $10,000 each).

  • Hugo van der Heide,

    1. Erasmus MC, University Medical Center Rotterdam, Rotterdam, The Netherlands
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  • Sten P. Willemsen,

    1. Erasmus MC, University Medical Center Rotterdam, Rotterdam, The Netherlands
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  • Christianne J. M. de Groot,

    1. Medical Center Haaglanden, The Hague, The Netherlands
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  • Eric A. P. Steegers,

    1. Erasmus MC, University Medical Center Rotterdam, Rotterdam, The Netherlands
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  • Radboud J. E. M. Dolhain

    1. Erasmus MC, University Medical Center Rotterdam, Rotterdam, The Netherlands
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Abstract

Objective

To determine the outcome of pregnancy in women with rheumatoid arthritis (RA) in relation to disease activity and medication use during the pregnancy.

Methods

In a prospective study, pregnant women with RA were evaluated before conception (when possible), during each trimester of the pregnancy, and postpartum. Clinical characteristics, disease activity, medication use, and pregnancy outcome were analyzed. To examine the independent influence of prednisone use and disease activity on birth weight, regression analyses were performed, with adjustments for gestational age of the child at delivery, the sex of the newborn, and the mother's smoking status, education level, parity, and use of an assisted reproduction technique. Kaplan-Meier curve analyses were performed to examine the association between medication use and gestational age at delivery.

Results

Data from 152 Caucasian RA patients with singleton pregnancies were available. Both the mean ± SD birth weight (3,379 ± 564 gm) and the mean ± SD birth weight standard deviation score (SDS; +0.1 ± 1.1), which is the birth weight adjusted for the gestational age and sex of the newborn, were comparable with those in the general population. On multiple linear regression analyses of birth weight and birth weight SDS, both of which were adjusted for covariates, only disease activity was associated with lower birth weight (P = 0.025). The gestational age at delivery was significantly lower in women who were taking prednisone (38.8 versus 39.9 weeks; P = 0.001), and their delivery was more often premature (<37 weeks; P = 0.004).

Conclusion

Pregnancy outcome in women with well-controlled RA is comparable with that in the general population. The effect of prednisone on birth weight is mediated by a lower gestational age at delivery, whereas a higher level of disease activity independently influences birth weight negatively, suggesting an immune-mediated mechanism.

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