Relationship between serum progesterone (P) levels and pregnancy outcome: lessons from artificial cycles when using vaginal natural micronized progesterone

Circadian serum progesterone variations on the day of frozen embryo transfer in artificially prepared cycles

RESEARCH QUESTION

What is the intra-day variation of serum progesterone related to vaginal progesterone administration on the day of frozen embryo transfer (FET) in an artificial cycle?

DESIGN

A prospective cohort study was conducted including 22 patients undergoing a single blastocyst artificial cycle (AC)-FET from August to December 2022. Endometrial preparation was achieved by administering oestradiol valerate (2 mg three times daily) and consecutively micronized vaginal progesterone (MVP; 400 mg twice daily). A blastocyst FET was performed on the 6th day of MVP administration. Serum progesterone concentrations were measured on the day of transfer at 08:00, 12:00, 16:00 and 20:00 hours. The first and last blood samples were collected just before MVP was administered.

RESULTS

The mean age and body mass index of the study population were 33.95 ± 3.98 years and 23.10 ± 1.95 kg/m2. The mean P-values at 08:00, 12:00, 16:00 and 20:00 hours were 11.72 ± 4.99, 13.59 ± 6.33, 10.23 ± 3.81 and 9.28 ± 3.09 ng/ml, respectively. A significant decline, of 2.41 ng/ml (95% confidence interval 0.81-4.00), was found between the first and last progesterone measurements.

CONCLUSION

A statistically significant intra-day variation of serum progesterone concentrations on the day of FET in artificially prepared cycles was observed. This highlights the importance of a standardized procedure for the timing of progesterone measurement on the day of AC-FET. Of note, the study results are applicable only to women using MVP for luteal phase support; therefore it is necessary to confirm its validity in comparison with the different existing administration routes of progesterone.

Progesterone: A Steroid with Wide Range of Effects in Physiology as Well as Human Medicine

Progesterone is a steroid hormone traditionally linked with female fertility and pregnancy. In current reproductive medicine, progesterone and its analogues play crucial roles. While the discovery of its effects has a long history, over recent decades, various novel actions of this interesting steroid have been documented, of which its neuro- and immunoprotective activities are the most widely discussed. Discoveries of the novel biological activities of progesterone have also driven research and development in the field of progesterone analogues used in human medicine. Progestogen treatment has traditionally and predominately been used in maintaining pregnancy, the prevention of preterm labor, various gynecological pathologies, and in lowering the negative effects of menopause. However, there are also various other medical fields where progesterone and its analogues could find application in the future. The aim of this work is to show the mechanisms of action of progesterone and its metabolites, the physiological and pharmacological actions of progesterone and its synthetic analogues in human medicine, as well as the impacts of its production and use on the environment.

Individualized luteal phase support normalizes live birth rate in women with low progesterone levels on the day of embryo transfer in artificial endometrial preparation cycles

OBJECTIVE

To analyze the impact on live birth rates (LBRs) of the individualized luteal phase support (termed iLPS) in patients with low serum progesterone (P) levels compared with patients without iLPS.

DESIGN

Retrospective cohort study, December 1, 2018, to May 30, 2019.

SETTING

Private medical center.

PATIENT(S)

A total of 2,275 patients checked for serum P on the day of blastocyst transfer were analyzed. During the study period, 1,299 patients showed serum P levels of ≥9.2 ng/mL, whereas 550 showed serum P levels of <9.2 ng/mL and received iLPS. Additionally, a historical group of 426 patients with serum P levels of <9.2 ng/mL but no iLPS were used for comparison. Eligible patients were aged ≤50 years with adequate endometrium morphology after receiving estrogens. Luteal phase support was provided with micronized vaginal P (MVP) to all women. Patients with personalized initiation of exogenous P according to the endometrial receptivity assay test, polyps, fibroids distorting the cavity, or hydrosalpinx were not included in the analysis.

INTERVENTION(S)

As routine practice since December 2018, patients with low serum P levels received an iLPS with a daily injection of 25 mg of subcutaneous P from the day of embryo transfer (ET) in addition to standard LPS (400 mg of MVP twice a day).

MAIN OUTCOME MEASURE(S)

Live birth rate.

RESULT(S)

The LBR was 44.9% in the iLPS cases vs. 45.0% in patients with normal serum P levels (crude odds ratio [OR], 1.0; 95% confidence interval [CI], 0.82-1.22). By regression analysis, low serum P levels did not affect the LBR after adjusting for possible confounders (age, oocyte origin, fresh vs. frozen, day of ET, embryo quality, number of embryos transferred) (adjusted OR, 0.99; 95% CI, 0.79-1.25). Similarly, no differences were observed in other pregnancy outcomes between groups. The LBR was significantly higher in the group of patients who received additional subcutaneous P (iLPS) compared with the historical group with low serum P levels and no iLPS (44.9% vs. 37.3%; OR, 1.37; 95% CI, 1.06-1.78). In the overall population, patients showing P levels of <9.2 ng/mL on the day of ET were slightly younger and had higher body mass index and lower estradiol and P levels during the proliferative phase compared with patients with P levels of ≥9.2 ng/mL. No differences were observed with regard to the time in between the last dose of MVP and the serum P determination. After a multivariable logistic regression analysis, only body mass index and estradiol levels in the proliferative phase reminded statistically significant. Significant differences in the LBR were observed between patients with serum P levels of <9.2 ng/mL without iLPS and patients with serum P levels of ≥9.2 ng/mL when using either own or donated oocytes.

CONCLUSION(S)

Individualized LPS for patients with low serum P levels produces LBRs similar to those of patients with adequate serum P levels.

New concepts and difficulties with progesterone supplementation in the luteal phase

PURPOSE OF REVIEW

Management of the luteal phase (LP) in assisted reproductive cycles has aroused interest in recent years. The reason is that it seems that the individualization of LP support may be necessary, since the concept of 'one size fits all' does not apply to this treatment.

RECENT FINDINGS

Studies carried out in hormone replacement therapy cycles (also called artificial cycles) have shown that serum levels of progesterone (P) are related to pregnancy outcomes. This represents a milestone in the management of artificial cycles (AC), because until a few years ago it was believed that serum levels did not really reflect the effectiveness of P, which is why they were neglected. However, it is not as straightforward as it seems, because the interpretation of serum progesterone values will depend on the type of progesterone used and its route of administration. Likewise, the findings observed in AC are not applicable to what occurs in a fresh transfer cycle after ovarian stimulation or an embryo transfer in the context of a natural cycle.

SUMMARY

In this manuscript, we will summarize the current situation in LP management.

Impact of low serum progesterone levels on the day of embryo transfer on pregnancy outcome: a prospective cohort study in artificial cycles with vaginal progesterone

STUDY QUESTION

Is there a serum progesterone (P) threshold on the day of embryo transfer (ET) in artificial endometrium preparation cycles below which the chances of ongoing pregnancy are reduced?

SUMMARY ANSWER

Serum P levels <8.8 ng/ml on the day of ET lower ongoing pregnancy rate (OPR) in both own or donated oocyte cycles.

WHAT IS KNOWN ALREADY

We previously found that serum P levels <9.2 ng/ml on the day of ET significantly decrease OPR in a sample of 211 oocyte donation recipients. Here, we assessed whether these results are applicable to all infertile patients under an artificial endometrial preparation cycle, regardless of the oocyte origin.

STUDY DESIGN, SIZE, DURATION

This prospective cohort study was performed between September 2017 and November 2018 and enrolled 1205 patients scheduled for ET after an artificial endometrial preparation cycle with estradiol valerate and micronized vaginal P (MVP, 400 mg twice daily).

PARTICIPANTS/MATERIALS, SETTING, METHODS

Patients ≤50 years old with a triple-layer endometrium ≥6.5 mm underwent transfer of one or two blastocysts. A total of 1150 patients treated with own oocytes without preimplantation genetic testing for aneuploidies (PGT-A) (n = 184), own oocytes with PGT-A (n = 308) or donated oocytes (n = 658) were analyzed. The primary endpoint was the OPR beyond pregnancy week 12 based on serum P levels measured immediately before ET.

MAIN RESULTS AND THE ROLE OF CHANCE

Women with serum P levels <8.8 ng/ml (30th percentile) had a significantly lower OPR (36.6% vs 54.4%) and live birth rate (35.5% vs 52.0%) than the rest of the patients. Multivariate logistic regression showed that serum P < 8.8 ng/ml was an independent factor influencing OPR in the overall population and in the three treatment groups. A significant negative correlation was observed between serum P levels and BMI, weight and time between the last P dose and blood tests and a positive correlation was found with age, height and number of days on HRT. Multivariate logistic regression showed that only body weight was an independent factor for presenting serum P levels <8.8 ng/ml. Obstetrical and perinatal outcomes did not differ in patients with ongoing pregnancy regardless of serum P levels being above/below 8.8 ng/ml.

LIMITATIONS, REASONS FOR CAUTION

Only women with MVP were included. Extrapolation to other P administration forms needs to be validated.

WIDER IMPLICATIONS OF THE FINDINGS

This study identified the threshold of serum P as 8.8 ng/ml on the day of ET for artificial endometrial preparation cycles necessary to optimize outcomes, in cycles with own or donated oocytes. One-third of patients receiving MVP show inadequate levels of serum P that, in turn, impact the success of the ART cycle. Monitoring P levels in the mid-luteal phase is recommended when using MVP to adjust the doses according to the needs of the patient.

STUDY FUNDING/COMPETING INTEREST(S)

None.

TRIAL REGISTRATION NUMBER

NCT03272412.

Viral infection of the ovaries compromises pregnancy and reveals innate immune mechanisms protecting fertility

Viral infections during pregnancy are a considerable cause of adverse outcomes and birth defects, and the underlying mechanisms are poorly understood. Among those, cytomegalovirus (CMV) infection stands out as the most common intrauterine infection in humans, putatively causing early pregnancy loss. We employed murine CMV as a model to study the consequences of viral infection on pregnancy outcome and fertility maintenance. Even though pregnant mice successfully controlled CMV infection, we observed highly selective, strong infection of corpus luteum (CL) cells in their ovaries. High infection densities indicated complete failure of immune control in CL cells, resulting in progesterone insufficiency and pregnancy loss. An abundance of gap junctions, absence of vasculature, strong type I interferon (IFN) responses, and interaction of innate immune cells fully protected the ovarian follicles from viral infection. Our work provides fundamental insights into the effect of CMV infection on pregnancy loss and mechanisms protecting fertility.