The fertilization rate (the number of 2PNs divided by the total number of MII oocytes), quality of obtained embryos, implantation rate (the number of intrauterine gestational sacs divided by transferred embryos), as well as clinical pregnancy rate (by detecting fetal heartbeats two weeks following the positive hCG) and ongoing pregnancy rate (a pregnancy documented by ultrasound over 20 gestational weeks that showed the presence of normal fetus)
In my opinion, its likely a little bit of both
PubMed Link Mulherin DM, Capell HA, Sturrock RD
Comparison of the total phenolic and ascorbic acid content of freeze-dried and air-dried marionberry, strawberry, and corn using conventional, organic, and sustainable agricultural practices
The potency of ghrelin stimulation can be compared to GHRP6 with less appetite stimulation properties