The association between level of physical activity and pregnancy rate after embryo transfer: a prospective study

Research question: Is physical activity after embryo transfer, as assessed by a smart band activity tracker, associated with decreased pregnancy rates? Design: Prospective observational cohort study comprising infertile women aged < 38 years, who had undergone fewer than three previous embryo transfers, achieved a good ovarian response and were undergoing frozen–thawed embryo transfer in a tertiary-referral centre. A validated smart band activity tracker was used to assess physical activity level immediately after the embryo transfer and until the pregnancy test. No specific recommendations were given to participants on level or intensity of physical activity. Physicians and patients were blinded to the data stored in the pedometer. Primary outcome was ongoing pregnancy rate. Results: Fifty women met the inclusion criteria. Ongoing pregnancy rate was 30%. In a pooled analysis, participants walked significantly fewer steps per day on the day of embryo transfer compared with the first 2 days after embryo transfer (4075, interquatile range [IQR] 2932–5592 versus 5204, IQR4203–8584, P = 0.01). No significant difference was observed between pregnant women and non-pregnant women in the median steps per day after embryo transfer until serum beta-HCG was measured (7569, IQR 6008–10884 versus 6572.5, IQR 5299–8786, P = 0.43). No significant difference was observed in the median number of steps on the day of embryo transfer or the first 2 days after embryo transfer between pregnant and non-pregnant women. Conclusions: A quantitative objective assessment of the association between physical activity and pregnancy rates after frozen–thawed embryo transfer was conducted. Ambulation after embryo transfer has no adverse effect on pregnancy rates and, therefore, women should resume regular activity immediately after embryo transfer.