Free your patients and yourself from day 2-3: start ovarian stimulation any time in freeze-all cycles

Undetected, natural conception pregnancies in luteal phase stimulations-case series and review of literature

STUDY QUESTION

What is the risk of an undetected natural conception pregnancy during luteal phase ovarian stimulation, and how does it impact the pregnancy's course?

SUMMARY ANSWER

The risk for an undetected, natural conception pregnancy in luteal phase ovarian stimulation is low and it appears that ovarian stimulation is unlikely to harm the pregnancy.

WHAT IS KNOWN ALREADY

Random start ovarian stimulation appears to be similarly effective as early follicular stimulation start; and it allows ovarian stimulation to be started independent of the cycle day and throughout the cycle, in accordance with the patients' and clinics' schedule as long as there is no intention of a fresh embryo transfer in the same cycle. Starting ovarian stimulation in the luteal phase bears the possibility of an-at the timepoint of stimulation start-undetected, natural conception pregnancy that has already occurred. There is scarce data on the incidence of this event as well as on the possible implications of ovarian stimulation on the course of an existing pregnancy.

STUDY DESIGN, SIZE, DURATION

This retrospective observational study, performed between June 2017 and January 2024, analyzed luteal phase stimulations, in which a natural conception pregnancy was detected during the ovarian stimulation treatment for IVF/ICSI. Luteal phase stimulation was defined as ovarian stimulation started after ovulation and before the next expected menstrual bleeding, with a serum progesterone (P4) level of >1.5 ng/ml on the day of stimulation start or 1 day before.

PARTICIPANTS/MATERIALS, SETTING, METHODS

Women who underwent a luteal phase ovarian stimulation in a tertiary referral ART center.

MAIN RESULTS AND THE ROLE OF CHANCE

A total of 488 luteal phase stimulation cycles were included in the analysis. Luteal phase stimulation was only started after a negative serum hCG measurement on the day or 1 day before commencement of ovarian stimulation. Ten patients (2.1%) had an undetected natural conception pregnancy at the time of luteal phase stimulation start. Eight of these patients underwent an ovarian stimulation in a GnRH-antagonist protocol and two in a progestin-primed stimulation protocol (PPOS). Recombinant FSH was used as stimulation medication for all patients, the patients with a PPOS protocol received additional recombinant LH. One pregnancy (0.2%) was detected after the oocyte retrieval, the other nine pregnancies were detected either due to persistent high serum progesterone levels or due to an increasing progesterone level after an initial decrease before oocyte retrieval. In the cycles with an undetected natural conception pregnancy, the median number of stimulation days was 8 days (range: 6-11 days) and median serum hCG at detection of pregnancy was 59 IU hCG (range: 14.91-183.1). From 10 patients with a pregnancy, three patients delivered a healthy baby, two patients had ongoing pregnancies at the time of summarizing the data, three patients had biochemical pregnancies (patient age: 30, 39, and 42 years), one patient had an ectopic pregnancy which required a salpingectomy, and one patient (age: 34 years) had an early pregnancy loss.

LIMITATIONS, REASONS FOR CAUTION

The retrospective study design and the small sample size can limit the accuracy of the estimates.

WIDER IMPLICATIONS OF THE FINDINGS

Overall, there is a small risk of undetected natural conception pregnancies when luteal phase stimulation is undertaken. It appears that there are no adverse effects through either direct effect on the embryo or indirectly through a detrimental effect on the corpus luteum function on the pregnancy in our cohort.

STUDY FUNDING/COMPETING INTEREST(S)

This study did not receive funding. The authors declare that there is no conflict of interest.

TRIAL REGISTRATION NUMBER

N/A.

Monitoring of controlled ovarian stimulation in IVF

Since the inception of in vitro fertilization (IVF), monitoring of controlled ovarian stimulation (COS) has traditionally involved numerous appointments for ultrasound and laboratory testing to guide medication use and dosing, determine trigger timing, and allow for measures to reduce the risk of ovarian hyperstimulation syndrome (OHSS). Recent advances in the field of assisted reproductive technology (ART) have called into question the timing and frequency of COS monitoring appointments, as discussed in this commentary.

The dark side of random-start ovarian stimulation: ovarian hyperstimulation syndrome due to inadvertent pregnancy

RESEARCH QUESTION

Can inadvertent pregnancies go unnoticed when initiating random-start ovarian stimulation (RSOS) despite monitoring?

DESIGN

Case series at a university-based tertiary care fertility clinic.

RESULTS

Between June 2022 and December 2023, two cases of undetected early pregnancy at the onset of RSOS were identified, both leading to severe ovarian hyperstimulation syndrome (OHSS) with hospitalization.

CONCLUSION

RSOS protocols add flexibility in fertility clinics when there is no intention of a fresh embryo transfer, but may be associated with insidious risk of OHSS. The authors advocate for comprehensive consultation and serial monitoring of human chorionic gonadotrophin during ovarian stimulation, while cautioning against over-reliance on baseline hormone concentrations when initiating RSOS. If the benefits of RSOS seem limited, healthcare providers should consider delaying ovarian stimulation to avert health, but also medicolegal and financial, complications.

Progestin-primed ovarian stimulation: for whom, when and how?

Progestin-primed ovarian stimulation (PPOS) is being increasingly used for ovarian stimulation in assisted reproductive technology. Different progestins have been used with similar success. The available studies suggest a similar response to ovarian stimulation with gonadotrophin-releasing hormone (GnRH) analogues. Any differences in the duration of stimulation or gonadotrophin consumption are minor and clinically insignificant. PPOS has the advantage of oral administration and lower medication costs than GnRH analogues. As such it is clearly more cost-effective for fertility preservation and planned freeze-all cycles, but when fresh embryo transfer is intended PPOS can be less cost-effective depending on the local direct and indirect costs of the additional initial frozen embryo transfer cycle. Oocytes collected in PPOS cycles have similar developmental potential, including blastocyst euploidy rates. Frozen embryo transfer outcomes of PPOS and GnRH analogue cycles seem to be similar in terms of both ongoing pregnancy/live birth rates and obstetric and perinatal outcomes. While some studies have reported lower cumulative live birth rates with PPOS, they have methodological issues, including arbitrary definitions of the cumulative live birth rate. PPOS has been used in all patient types (except progesterone receptor-positive breast cancer patients) with consistent results and seems a patient friendly and cost-effective choice if a fresh embryo transfer is not intended.