Modified natural cycle in in vitro fertilization

Abstract

The first live birth after IVF was achieved in a purely natural cycle. Because early attempts at IVF were associated with low efficiency, ovarian stimulation was added to achieve a greater margin for error in oocyte retrieval, fertilization, and thus, overall pregnancy success. As technology improved, the intuitive appeal of the natural cycle led investigators to once again attempt IVF without antecedent gonadotropin stimulation. Triggering of ovulation with hCG was added to allow for accurate scheduling of oocyte retrieval and thus increased oocyte yield. When GnRH antagonists became available, premature ovulations could be prevented, albeit at the cost of adding some form of ovarian stimulation to continue follicle development until ovulation triggering. This type of cycle came to be known as the "modified natural cycle." These modified natural IVF cycles are associated with decreased medication costs, they produce acceptable pregnancy rates, and they may be particularly appropriate for patients at increased risk of ovarian hyperstimulation syndrome, poor responders, and those wishing to avoid supernumerary embryo production.

Procriação Medicamente Assistida em Ciclo Natural: Avaliação dos Resultados de um Departamento de Medicina da Reprodução

“…Assim sendo, parece haver melhor qualidade ovocitária nos ciclos naturais, que é atribuída à seleção natural de um folículo dominante. 31 Alguns autores apontam os ciclos naturais modificados com um antagonista da GnRH como uma alternativa aos ciclos naturais para as mulheres más respondedoras, uma vez que se associam a menor incidência de pico de LH prematuro e, consequentemente, a menor taxa de cancelamento do ciclo. 24,32 Estudos recentes sugerem, para os ciclos naturais em más respondedoras, a utilização de progesterona oral a partir do terceiro dia do ciclo de forma a evitar o pico de LH espontâneo e a ovulação prematura, não afetando a qualidade ovocitária.…”

Pregnancy and neonatal outcomes of small follicle–derived blastocyst transfer in modified natural cycle in vitro fertilization

“…We conducted a retrospective cohort study on BTs that were performed between January 2012 and December 2014 at our infertility clinic. The inclusion criteria were as follows: [1] the blastocysts were grown from oocytes that were retrieved by the modified natural cycle IVFs, conducted as the initial one or two attempts of IVF-ET for the patients in our clinic; [2] both large (dominant, R11 mm) follicles and small (nondominant, %10 mm) follicles were concurrently aspirated at oocyte retrieval; [3] oocytes had matured to metaphase II when they were inseminated; and [4] patients were between 30 and 40 years old. Patients who did not agree with natural cycle IVF or this study were excluded.…”

“…Natural cycle IVF-ET does not stimulate the ovary; consequently, it is lower in cost, and there is no fear of ovarian stimulation-related symptoms and risks. However, a drawback of natu-ral cycle IVF-ET is that the number of oocytes achievable is generally limited to one per cycle (1).…”

“…Therefore, the concurrent puncture of SFs nearly doubles the live birth ratio of the traditional natural cycle IVF in which oocytes are only retrieved from LFs. SFs appear to be a promising source of additional oocytes in natural cycle IVF (1,3). However, there has been a limited number of patients, and information regarding anomalies of the live birth babies is missing thus far.…”

Modified natural cycle IVF is a reasonable alternative in women of advanced maternal age

“…Secondly, the claim that embryo availability was part of the regression model is inaccurate. In fact, the variable 'top quality embryo' was the confounder included and evidence supports that embryo quality is not related to ovarian stimulation regimen (Ziebe, et al, 2004, Ho andPaulson, 2017).…”