The association between physical activity level and pregnancy rate following embryo transfer: A prospective study

Abstract Research Question Is physical activity following embryo transfer (ET), as assessed by a smart-band-activity-tracker, associated with decreased pregnancy rates? Design A prospective observational cohort study comprising infertile women, younger than 38, with less than three previous ETs and a good ovarian response, undergoing frozen-thawed ET in a tertiary-referral center. Physical activity level was assessed by a validated smart-band-activity-tracker immediately following the ET and until conducting a pregnancy test. No specific recommendations were given to the participants as to the level or intensity of physical activity. Both physicians and patients were blinded to the data stored in the pedometer. The primary outcome was ongoing pregnancy rate. Results Fifty women met the inclusion criteria. The ongoing pregnancy rate was 30%. In a pooled analysis, participants walked significantly fewer steps per day on the day of ET compared to the first two days after ET (4075,IQR 2932-5592 vs. 5204, QR 4203-8584,p=0.01). There was no significant difference between pregnant women to non-pregnant women in the median steps per day in the period following ET until serum β-hCG was measured (7569,IQR 6008-10884 vs. 6572.5,IQR 5299-8786,p=0.43). Furthermore, there was no significant difference in the median number of steps on the day of ET or the first two days following ET between pregnant to non-pregnant women. Conclusions This study represents the first quantitative objective assessment of the association between physical activity and pregnancy rates following ET. The study demonstrates that ambulation following ET has no adverse effect on pregnancy rates, and therefore women should resume regular activity immediately after ET.