Ankylosing Spondylitis and Pregnancy

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Medical Author: William C. Shiel Jr., MD, FACP, FACR

The influence of pregnancy, delivery, and the post-partum period is a common concern of persons with arthritis and related conditions. Although ankylosing spondylitis occurs predominantly in men (two to three times more common in males than in females), women can and do develop the disease.

This topic of pregnancy and ankylosing spondylitis was studied and published under the title "Ankylosing spondylitis--the female aspect" (J Rheumatol 1998 Jan;25[1]:120-4). I think this study serves well as a review of pregnancy issues in women with ankylosing spondylitis.

In collaboration with the Ankylosing Spondylitis International Federation, a questionnaire including clinical data and details on past and recent pregnancies was sent to the female members of national and regional Ankylosing Spondylitis societies in the USA, Canada, and 11 European countries. (It should be noted that questionnaires do have shortcomings from a research standpoint, including inaccurate completion of the forms, lack of personal interaction, and accurate interpretation of both the questions and the responses.)

Nine hundred thirty-nine questionnaires were completed. The researchers found that the average age of the responding women at the onset of their ankylosing spondylitis was 23 years. In 21% of these women, the onset was related to a pregnancy, either occurring during or immediately after the pregnancy.

In this group, the frequency of accompanying features of ankylosing spondylitis was as follows: 45% had inflamed joints away from the spine (peripheral arthritis); 48% had inflammation of the iris of the eye (acute anterior uveitis); 18% had psoriasis; and 16% had inflammatory bowel disease.

Six hundred forty-nine of the responding women with previous pregnancies had on average 2.4 pregnancies per woman, of which 1.4 pregnancies were during periods of disease. Of these pregnancies, 15.1% of women with ankylosing spondylitis experienced a miscarriage. During 616 previous and 366 recent pregnancies, disease activity was unchanged in 33.2%, improved in 30.9%, and worsened in 32.5%. Improvement of disease activity during pregnancy was correlated with a history of having peripheral arthritis. It was also observed significantly more often among those having a female rather than a male child. (It would have been even more interesting if the researchers had compared the activity of disease over the same period of time of patients with ankylosing spondylitis who were not pregnant.)

Delivery occurred at term in 93.2% of cases. The rate of cesarean section was high and due to ankylosing spondylitis in 58% of cases. The majority of the newborns were healthy and had a mean birth weight of 7.4 pounds. Ankylosing spondylitis had an adverse effect on being a mother and a caregiver as a result of active pain and stiffness.

A postpartum flare of the ankylosing spondylitis within six months after delivery was experienced by 60% and most often with patients who had active disease at conception. This is consistent with the known frequency of flare-up of inflammation in a majority of patients in the postpartum period. It should be noted that active disease at conception was a predictor of a postpartum flare.

In the particular study above, there were no control groups. The results of this study would have been even more powerful if some of the key numbers had been compared to a control group without pregnancy or without ankylosing spondylitis.

Ankylosing spondylitis does not seem to adversely affect fertility, the developing baby in the womb, or the newborn. It seems that improvement during pregnancy occurs more frequently in women with a history of peripheral arthritis and those with a female fetus.