Background: Constipation during pregnancy is a common problem. Nowadays only few effective interventions are published preventing or treating constipation during pregnancy. However, their use is limited due to side-effects. This uncontrolled intervention study was performed to determine if a mixture of probiotics in the treatment of constipation during pregnancy is effective. Methods. Women aged18 years with functional constipation were included at the Obstetrical outpatient clinic and midwife practices. Patients received during four weeks a daily dose of Ecologic®Relief (Bifidobacterium bifidum W23, Bifidobacterium lactis W52, Bifidobacterium longum W108, Lactobacillus casei W79, Lactobacillus plantarum W62 and Lactobacillus rhamnosus W71 (total 4*109 CFU)). For all analyses, the non-parametric paired Wilcoxon test was used. Primary outcome measure was change in defecation frequency. Secondary outcome measures were stool consistency, sensation of incomplete evacuation, sensation of anorectal obstruction, manual manoeuvres to facilitate defecation, abdominal pain, adverse effects, presence of reflux episodes and intake of Bisacodyl. Results: 20 women were included. Defecation frequency significantly increased from 3.1 at baseline to 6.7 in week four (p<0.01). Compared to baseline, a significant decrease in 1) sensation of anorectal obstruction from 90.0% to 45.0% (p<0.01), 2) sensation of incomplete evacuation from 90.0% to 40.0% (p<0.01), 3) straining during defecation from 100% to 65% (p=0.01), 4) episodes of abdominal pain from 60% to 20% (p=0.01) and 5) the presence of reflux episodes from 60% to 20% in week four (p=0.01) was found. Other secondary outcomes did not decrease significantly. No side effects were reported. Conclusions: Ecologic®Relief is effective in the treatment of constipation during pregnancy. A randomised placebo controlled trial is required to confirm these data. © 2012 de Milliano et al.; licensee BioMed Central Ltd.