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Reprod Biomed Online. 2017 Apr;34(4):345-353. doi: 10.1016/j.rbmo.2017.01.010. Epub 2017 Jan 24.

Ovarian stimulation protocols for IVF: is more better than less?

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Boston IVF, 130 2nd Avenue, Waltham, MA 02451, USA. Electronic address:
Department of Reproductive Medicine and Gynecology, University Medical Center Utrecht, Heidelberglaan 100, 3584 CX Utrecht, The Netherlands.


Conventional ovarian stimulation protocols for IVF are designed to achieve maximum oocyte yields. Conventional protocols, however, are associated with patient discomfort, increased risk of ovarian hyperstimulation syndrome and higher costs. In recent years, mild stimulation protocols have risen in popularity. These protocols typically use lower doses (≤150 IU/day), shorter duration of exogenous gonadotrophins, or both, compared with conventional protocols, with the goal of limiting the number of retrieved oocytes to less than eight. The pregnancy rate per cycle (fresh embryo transfer only) is lower with mild stimulation compared with conventional stimulation; however, the cumulative pregnancy rate seems to be comparable between the approaches. Reports are conflicting on the effects of mild versus conventional stimulation on embryo quality. This article expands on a live debate held at the American Society for Reproductive Medicine 2015 Annual Meeting to compare the advantages and disadvantages of the 'more is better' (conventional protocol) versus 'less is best' (mild protocol) approaches to ovarian stimulation. Both protocols are associated with benefits and challenges, and physicians must consider the needs of the individual patient when determining the best treatment options. Further prospective studies comparing a variety of outcomes with conventional and mild stimulation are needed.


Assisted reproduction; Gonadotrophin; IVF/ICSI outcome; Ovarian hyperstimulation syndrome; Ovarian stimulation

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