OBJECTIVES: Willis-Ekbom disease/restless legs syndrome (WED/RLS) is the most 
common sleep-related movement disorder in pregnancy. We designed a prospective 
longitudinal study to investigate the correlates of WED/RLS during and after 
pregnancy.
DESIGN: A total of 138 pregnant women with WED/RLS and a control group of 251 
age-matched pregnant women were enrolled prospectively. A questionnaire was 
administered during a face-to-face interview at first evaluation during 
pregnancy and three months after delivery.
RESULTS: Among all women in the first trimester, 15.6% were diagnosed with 
WED/RLS, whereas 32.8% of those in the second trimester and 38.8% of those in 
the third trimester were diagnosed with WED/RLS (p = 0.032). In regression 
analysis, later gestational age [p < 0.001; odds ratio (OR) 1.054] and previous 
history of WED/RLS (p = 0.001; OR 2.795) were positively correlated with the 
presence of WED/RLS, while ferritin levels (p = 0.001; OR 0.956) were negatively 
correlated with the presence of WED/RLS. Ferritin levels were also negatively 
correlated with the International RLS Study Group severity index (p = 0.041). 
Forty-eight patients (34.8%) experienced WED/RLS symptomatology after delivery. 
The ferritin levels were lower, and the mean number of pregnancies was higher, 
in women with residual WED/RLS (p = 0.008).
CONCLUSION: Our survey showed that WED/RLS was more common in the second and 
third trimesters. Emergence of WED/RLS during the second trimester was strongly 
associated with residual WED/RLS. Lower ferritin levels were associated with 
both WED/RLS in pregnancy and residual WED/RLS after delivery. A higher number 
of pregnancies were also associated with a greater likelihood of having residual 
WED/RLS after delivery.