Does pregnancy increase curve progression in women with scoliosis treated without surgery?

ABSTRACT

Study design: Systematic review.

Study rationale: It is commonly believed that scoliosis treated nonoperatively does not worsen in pregnancy; however, at times patients with scoliosis progress rapidly during these months.

Objective or clinical question: What is the level of evidence to support or deny the claim that scoliosis treated nonoperatively does not worsen in pregnancy?

Methods: A systematic review of the literature was undertaken for articles published through March 2011. PubMed, Cochrane, National Guideline Clearinghouse Databases as well as bibliographies of key articles were searched. Two independent authors reviewed articles. Inclusion and exclusion criteria were set and each article was subject to a predefined quality-rating scheme.

Results: We identified two articles meeting our inclusion criteria. There was no difference in risk of curve progression > 5° or > 10° between women who had one or more pregnancies compared with those who had never been pregnant. However, among women who had been treated with an orthosis, those with one or more pregnancies had a higher risk of curve progression > 5° compared with never-pregnant women: relative risk = 8.1 (95% confidence interval: 1.8 – 35.8) in one study and 1.9 (95% confidence interval: 0.8 – 4.3) in the other. While women with more severe curves had a higher risk of curve progression, having one or more pregnancies did not appear to modify the effect of curve severity.

Conclusions: Having one or more pregnancies does not appear to affect curve progression in scoliosis. However, among patients who had prior orthotic treatment, there is some evidence to suggest that women experiencing one or more pregnancies had a higher risk of curve progression compared with never-pregnant women. The overall strength of evidence for this conclusion is low.

This study was not financially supported and the authors have no conflict of interest to disclose.

REFERENCES

• 1 Cochran T, Nachemson A. Long-term anatomic and functional changes in patients with adolescent idiopathic scoliosis treated with the Milwaukee brace.  Spine. 1985;  10 (2) 127-133
• 2 Betz R R, Bunnell W P, Lambrecht-Mulier E. et al . Scoliosis and pregnancy.  J Bone Joint Surg Am. 1987;  69 (1) 90-96
• 3 Mooney V, Gulick J, Pozos R. A preliminary report on the effect of measured strength training in adolescent idiopathic scoliosis.  J Spinal Disord. 2000;  13 (2) 102-107
• 4 Edgar M A. The natural history of unfused scoliosis.  Orthopedics. 1987;  10 (6) 931-939
• 5 Hassan I, Bjerkreim I. Progression in idiopathic scoliosis after conservative treatment.  Acta Orthop Scand. 1983;  54 (1) 88-90

EDITORIAL PERSPECTIVE

The reviewers congratulate Schroeder and colleagues for selecting an interesting topic with contentious undertones. Our reviewers and the EBSJ editorial staff were surprised that for a topic that is seemingly such an established medical fact („Scoliosis is not caused or accelerated by pregnancy!“) the actual evidence base is rather thin, to put it kindly. The lack of evidence base for determination of a relationship of pregnancy and cure progression in scoliosis is very low that it is difficult to draw any observations, and certainly not to the degree of counseling patients about the influence of pregnancy on their curve progression or eventual treatment needs.

Here are some observations from our reviewers:

• The types of scoliosis (adolescent onset idiopathic, infantile onset idiopathic, congenital variants, adult onset, neuromuscular, and mechanical to name but a few) appears not differentiated in the available literature. In addition, curve types (using Lenke, King, or other classification systems and initial curve magnitude as well as age of first treatment may all be huge factors) in establishing curve progression risks. There could be differences in responses to pregnancy for curve subtypes, location, and magnitude.

• It needs to be emphasized that for obvious reasons, this systematic review assesses progression in adulthood. The Betz and coworkers" study compared progression from baseline of diagnosis, which uses adolescents not adulthood. So the question not answered by the current state of our literature is how much curve progression occurred before adulthood?

• Another unanswered question is what to measure in patients with known scoliosis? Is curve progression expressed in Cobb angles really relevant? Or should we focus on other factors, such as curve decompensation, occurrence rates of back pain expressed as consumption of health resources (such as visits to health professionals for low back pain) or conversion rate of patients to surgically treated backs? The current focus on Cobb angle alone seems not reflective of the actual problem.

There appear to be problems with inclusion of males in the Cochrane review on this topic. This study limitation confounds the results of the „never pregnant“ category.

All reviewers agreed with the authors that the question of pregnancy causing curve progression in adulthood cannot be answered based on currently published literature. Moreover, the present approach of using skeletally immature patients as baseline does not provide a suitable platform to approach the cardinal question. A prospective study design with registry-type approach would be more appropriate to answer the question of the interrelation of scoliosis curve progression and pregnancy.