High Doses of FSH in Small Ovarian Reserve heifers Reduced Estradiol Levels and Ovulation Rate

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High doses FSH small low ovarian reserve female heifers infertility reduce ovulation rate

Negative Impact of High Doses of Follicle-Stimulating Hormone During
Superovulation on Ovulatory Follicle Function in Small Ovarian Reserve Dairy

A study using heifers with small ovarian reserves as the experimental model was carried out to investigate the link between high doses of gonadotrophins and high oocyte, embryo wastage and low live births in women with low ovarian reserves undergoing IVF. Eight heifers underwent a superovulation regimen which included 35 IU, 70 IU, 140 IU or 210 IU of FSH, injected twice a day for a total of four days. The number and size of follicles was checked daily, as well as uterine thickness plus levels of estradiol, progesterone and AMH. Each heifer underwent each of the 4 doses being tested to eliminate potential variability between the animals.

Statistical analysis of the results found that AMH concentrations remained the same however antral follicle count (AFC) and the number of ovulatory size follicles (≥10 µm) increased, and was significantly different between the 35 IU and 210 IU treatments, before and after hCG administration. As expected estradiol levels also increased with increasing number of antral and ovulatory size follicles, however heifers in the 210 IU treatment group had lower estradiol levels pre-hCG and post-hCG administration, than either of the 70 IU or 140 IU treatments.

Unsurprisingly pre-hCG the number of corpora lutea and progesterone levels decreased in all groups, followed by an increase in the number of corpora lutea and progesterone levels post-hCG, which was seemingly not affected by FSH dose levels. Uterine thickness post-hCG was reduced by approximately 35% however this was not significantly altered by the different doses. Finally ovulation rates were not significantly different between the four groups, however when comparing the 35 and 70 IU group combined to the 140 and 210 IU group combined, the higher dose of FSH did show a statistically significant reduction in ovulation rates.


  1. Low sample number
  2. FSH dose levels in heifers do not translate directly to human requiring further studies

Similar studies

Baker V L, et al. (2015). Gonadotropin dose is negatively correlated with live birth rate: analysis of more than 650,000 assisted reproductive technology cycles. https://doi.org/10.1016/j.fertnstert.2015.07.1151

Pal L, et al. (2008). Less is more: increased gonadotropin use for ovarian stimulation adversely influences clinical pregnancy and live birth after in vitro fertilization. https://dx.doi.org/10.1016/j.fertnstert.2007.05.055

Klinkert E R, et al. (2005). Expected poor responders on the basis of an antral follicle count do not benefit from a higher starting dose of gonadotrophins in IVF treatment: a randomized controlled trial. https://doi.org/10.1093/humrep/deh663


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