P-635 RELATION BETWEEN THE TIME OF CONTROLLED OVARIAN STIMULATION IN PROGESTIN AND GnRH ANTAGONIST PROTOCOLS AND THE OUTCOMES OF IVF – A RETROSPECTIVE OBSERVATIONAL STUDY
Authors: Ramos Seixas N , Baldin C , Feliciano Orlandini M , Ingold C , Parete Barbosa C 
Published: June 2023

Study question

Comparison between IVF outcomes of two controlled ovarian stimulation (COS) protocols (the antagonist protocol and the progestin protocol) and their duration.

Summary answer

This data suggests that the protocols have comparable efficiency on the ovarian stimulation, leading to similar outcomes on IVF treatments.

What is known already

Both protocols aim to prevent early ovulation by blocking the LH surge but have slightly different mechanisms: the antagonist protocol uses a GnRH antagonist to block LH whereas in the progestin protocol a progestogen is administered. The aim of COS is to stimulate follicular growth for oocyte punction, avoiding an early ovulation. In this sense, some studies have shown that the use of oral dydrogesterone can offer a more stable maintenance of LH levels, with less occurrence of an early peak of this hormone, leading to fewer cases of premature ovulation and cycle cancellation.

Study design, size, duration

In this retrospective observational study data were collected from patients undergoing in vitro fertilization (IVF) treatment at Instituto Ideia Fértil between September 2019 and September 2020. The study was submitted to the evaluation of the Ethics and Research Committee (CEP) of the Faculdade de Medicina do ABC (CAAE: 54150621.8.0000.002) and approved. A total of 447 patients were included in the study, with 205 undergoing the antagonist protocol and 242 the progestin protocol.

Participants/materials, setting, methods

The participants were women of reproductive age that have undergone IVF at Instituto Ideia Fértil between September 2019 and 2020. They were divided between two groups: L-COS, which refers to cycles lasting ≥ 9 days, and S-COS, with cycles lasting ≤ 8 days. The variables included in the statistical analysis were: age, basal antral follicle count, and numbers of days of COS, collected and MII oocytes, zygotes, cleaved embryos and blastocysts.

Main results and the role of chance

Of the 447 patients, 392 underwent L-COS and 55 S-COS. Mean age was 38.5. When comparing groups, there was no statistical difference in the basal AFC (antral follicle count), average of recovered oocytes, mature oocytes, cleaved embryos, and blastocysts. There was a difference in the mean number of zygotes, which was greater in the L-COS group (2.77 ± 2.38 - 2.05 ± 2.16; p &lt; 0.05). However, the final outcome did not show superiority, since the number of cleaved embryos and blastocysts did not show a significant difference. There were no significant differences between the L-COS and S-COS groups of women submitted to the progestin protocol for any outcomes. When comparing the outcomes of the L-COS and S-COS groups of women submitted to the antagonist protocol, a significant difference in the basal AFC was observed, which was higher in the L-COS group (3.87 ± 1.69 - 3.0 ± 1.57; p &lt; 0.05), which may justify the need for more days of ovulation induction for oocyte growth and maturation. No other outcomes showed a significant difference between groups. Therefore, the duration of the COS does not appear to have an impact on outcomes in either the progestin or antagonist protocols.

Limitations, reasons for caution

The limitations of this study are the lack of data on BMI (body mass index), pregnancy rate and live birth rate, which does not allow us to analyze the future success of each of the ovarian stimulation protocols or trace the relationship between BMI and IVF.

Wider implications of the findings

This study showed no relevant differences between protocols. As the progestin protocol is cheaper and easier to administer and seems to have the same quality as the antagonist protocol it might be an interesting alternative, despite another step on the treatment, the freeze all.

Trial registration number

CAAE: 54150621.8.0000.002