The effect of bromocriptine-rebound method on ongoing pregnancy and live birth after intracytoplasmic sperm injection cycles: a randomized clinical trial

Ashraf Alleyassin¹ MD, Ramak Esmailizad² MD, Marzieh Agha-Hosseini³ MD,

Leila Safdarian³ MD, Fatemeh Sarvi⁴ MD, Abas Kokab⁵ PhD

¹Professor, Gynecologist, Infertility Department, Tehran University of Medical Sciences, Tehran, Iran.

²Gynecologist, Infertility Department, Tehran University of Medical Sciences, Tehran, Iran.

³Associate Professor, Gynecologist, Infertility Department, Tehran University of Medical Sciences, Tehran, Iran.

⁴Assistant Professor, Gynecologist, Infertility Department, Tehran University of Medical Sciences, Tehran, Iran.

⁵Andrologist, Infertility Department, Tehran University of Medical Sciences, Tehran, Iran.

ABSTRACT

Purpose: To assess whether bromocriptine rebound method (BRM) can improve pregnancy outcomes compared to long protocol after intracytoplasmic sperm injection (ICSI) cycles.

Materials and Methods: A total of 114 women underwent ICSI. Pregnancy outcomes and hormonal data were compared between two groups: long protocol and BRM. Ovulatory women with normal serum prolactin levels were assigned to either BRM (n=57 cycles) or long protocol (n=57 cycles). Both procedures were carried out in a similar way. However, a group of patients were given bromocriptine daily from the 4^th day of the preceding cycle until 7 days before gonadotropin stimulation.

Results: There were no significant differences in the numbers of developed follicles, total retrieval oocytes, embryo transferred and embryos with superior morphologic between the two groups. Also, the values of chemical, clinical and ongoing pregnancies and live births were not significantly different (36.8%, 35.1%, 28.1%, 28.1% in BRM group and 43.9%, 38.6%, 21.1% and 19.3% in long protocol, respectively). Ongoing pregnancy and live birth were significantly higher in chemical pregnancy in the BRM group.

Conclusion: This prospective study has demonstrated that BRM might lead to higher ongoing pregnancy and live birth rates compared to the long protocol in women undergoing ICSI cycles.

Keywords: Bromocriptine; ICSI; Live birth; Prolactin.

INTRODUCTION

Assisted reproductive technology (ART) has a significant role in treating infertility among couples with broad range of causes. Despite the advances in ART, the success of individual cycle to a live birth is still low (1). This can be related to poor response to ovulation induction or implantation failure (2, 3). Different protocols have been recommended to optimize follicular development; however the best protocol to improve ovarian stimulation has yet to be recognized.

Several studies have suggested that prolactin has an important role in regulating all ovarian functions (4, 5). For instance, Kiapekou et al assessed different isoforms of prolactin receptors in ovaries of mice. Their investigations revealed that the prolactin pathway is active in preantral follicles and PRL induces oocytes maturation, fertilization and early embryonic development (6). Also, Ozaki et al showed that mid-luteal serum prolactin levels were significantly lower in patients with early pregnancy loss (7). In addition, Oda et al have shown that the higher mean serum prolactin concentrations prior the oocyte retrieval increases the fertilization and cleavage rates compared to euprolactinemic and hypoprolactinemic cycles (5).

A novel method has been evolved by Jinno et al based on rebound phenomena after bromocriptine administration (8). They reported that this protocol will boost the response following ovarian stimulation leading to good quality oocytes. In this protocol, women with normal serum prolactin levels were recruited. Bromocriptine 2.5mg per day was orally administered from day 5 of the preceding cycle until 7 days before ovarian stimulation. After that ovarian stimulation similar to long protocol was started. They claimed that oocyte maturation improvement in patients may be due to restoring post receptor responsiveness of granulose cells to prolactin during the hypoprolactinemic period and increasing of the prolactin concentration by a rebound phenomenon after discontinuation of bromocriptine. Very limited number of researches has been published in assessing this protocol. Although this protocol seems to be promising, its effectiveness is still to be evaluated. The current study intends to specifically address the oocytes quality, embryo quality, pregnancy rate, ongoing pregnancy, and live birth following bromocriptine rebound method (BRM).

MATERIALS AND METHODS

This study was a prospective controlled randomized clinical trial involving 114 volunteer patients attending our outpatient clinic, infertility center. The patients were chosen between March 2009 and August 2010. The ethical approval of this study was obtained from the Ethics Committee of Tehran University of Medical Sciences. The patients received written information about the study and potential complications of ART, followed by an oral discussion and a formal consent. The outcomes of ICSI and hormonal data were compared between 57 patients on long standard protocol and 57 patients on the BRM.

The patients who were enrolled in the study had to have normal hormonal screen in days 2-4 of cycle for FSH (<10 IU/ml), LH, estradiol, thyroid-stimulating hormone (TSH) and prolactin. In addition, they were younger than 40 years and their ovulatory cycle as determined by serum progesterone in late secretary phase. Women with ovulatory cycles were excluded from this study. Patients with severe male factor in sperm analyses according to WHO criteria were also excluded (9).

The patients randomly were assigned to receive BRM or standard long protocol, the GnRH agonist and recombinant FSH regimen for ovarian stimulation. The randomization was based on computer-generated numbers in 19 blocks of 6 that were concealed until the time of interventions. Both the patients and the clinicians were aware of the allocation.

All patients of this study were treated with long protocol for ovarian stimulation. OCP was started for pituitary down-regulation from day 3 preceding cycle. Patients were treated with daily administration of 0.5mg buserelin (Superfact, Aventis, Frankfurt, Germany) from day 21 of menstrual cycle. Buserelin was reduced to 0.25 mg daily when ovaries were suppressed based on ultrasound, and ovarian hyperstimulation was initiated with recombinant FSH (Gonal F, Serono, Switzerland) in different doses according to ovarian antral follicle count in ultrasonography on day 2 of withdrawal bleeding.

In the BRM gruop, bromocriptine (2.5 mg/day, Tehran, Iran) was administered orally daily from day 3 of the preceding cycle until 7 days before ovarian stimulation. Serial ultrasound examinations were done to assess ovarian response, and then gonadotropin dose adjustments were done as required. Human chorionic gonadotropin (Pregnyl, Organon, Netherlands) 10,000 IU was administered when at least two follicles reached a mean diameter of 18mm. Oocytes retrieval was performed 36 hours after human chorionic gonadotropin (hCG) administration and oocytes were inseminated with ICSI. Embryo transfer was performed on the 2^nd day. Luteal support with progesterone in oil (Progesterone, Aburaihan Co., Tehran, Iran) 25 mg daily IM and vaginal suppository Cyclogest (Cox Pharmaceutical, Barnstaple, UK) was started on the day of oocytes retrieval and the documentation of fetal heart activity on ultrasound was continued. The ART cycles outcomes of interest were live birth rate (delivery of gestation) and clinical pregnancy rate (defined as an intrauterine gestational sac by ultrasound). ICSI outcomes and hormonal data were compared between the two groups to examine clinical efficacy of the BRM.

Statistical analysis

The data were analyzed with the Statistical Package for the Social Science Version 17 (SPSS Inc, Chicago, IL, USA). The normality of quantitative data was checked by histogram and one sample Kolmogorov-Smirnov test. Due to the non-parametric distribution of continuous data, Mann–Whitney U test was used to compare the data of the two groups. Qualitative variables were compared with chi-square or Fisher exact tests when appropriate. Two tailed P < 0.05 was taken as significant.

RESULTS

No significant differences were observed between BRM and long protocol groups in respect to mean age, BMI (body mass index), infertility duration, and primary or secondary infertility (Table 1). The serum of FSH, LH, TSH, Estradiol and prolactin demonstrated no significant differences between the two groups as shown in Table 2. Also, there were no significant differences between the two groups regarding the number of developed follicles, total retrieval oocytes, embryos transferred, and embryos with superior morphology (Table 1).

The chemical pregnancy rates were 36.8% and 43.9% in the intervention and control group, respectively, which is not statistically different (P= 0.445) and led to clinical pregnancy in 35.1% of intervention subjects and 38.6% of control subjects (P= 0.698). Ongoing pregnancy occurred in 28.1% and 21.1% of the subjects (P= 0.384) among the intervention and control group, respectively. All of the ongoing pregnancies led to live birth except one in the control group due to fetal anomaly (P= 0.271).

The rate of abortion was lower in the intervention group, i.e. 23.8%, compared to 52% in the control group which was significant (P= 0.051). More women who achieved chemical proven pregnancy on the long protocol ended their pregnancy due to miscarriage compared to the other group. On the other hand, the live birth rate was higher in intervention group, i.e. 28.1%, compared to 19.3% in the control group which was not significant (P= 0.271).

5 out of 16 (31.3%) live births in the intervention group and 2 out of 11 (18.2%) live births in the control group were twins (P= 0.661). Finally, women on long protocol who achieved chemical pregnancy had more miscarriage compared to BRM. It is of surprise that in 7% of women receiving BRM, the clinical manifestation of OHSS have been observed. This state in women receiving long protocol was 3.5% in our study.

DISCUSSION

The current study is the first to support the results of a prospective study on women using BRM. In a prospective randomized trial, Jinno et al compared IVF cycles outcomes between patients on BRM and long protocol using GnRH agonist in women with previous IVF failure (10). Their study demonstrated that patients on BRM had higher number of follicles, fertilized oocytes and embryos with top quality morphology. They concluded that clinical pregnancy rates and live birth rates per cycles were higher in women on BRM.

In another study, Jinno et al compared IVF outcomes between three groups: long protocol, bromocriptine rebound regimen and bromocriptine continuous regimen. Their results demonstrated that higher fertilization rates, cleavage rates, proportion of good quality embryos and pregnancy rates per oocytes retrieval were higher in BRM (8). Also, they designed another research to answer why BRM improves IVF outcomes (11). In this study they described an increase in serum prolactin concentration and prolactin post receptor mRNA of granulose cells in patients with poor response to ovulation induction. During BRM, there is recovery of post receptor response during hypoprolactinemia period due to bromocriptine administration and increasing of serum PRL levels as a rebound after bromocriptine discontinuation.

In our study, there was no significant differences in good quality retrieved oocytes and embryos with superior morphology between subjects in BRM and long protocol groups. In the present prospective randomized clinical trial, while chemical, clinical and ongoing pregnancy rates were equal in both BRM and long protocol groups, comparing these two groups in chemical pregnancy positive population, showed a significant higher rates of ongoing pregnancy and live birth in BRM group which indicates a better maintenance of pregnancy in the BRM group compared to the long group. Moride et al reported that using BRM in women with previous failed ART attempts, is associated with better quality retrieved oocytes and morphology of embryos (12). In addition, Mendes et al revealed that transient hyperprolactinemia was associated with a more mature oocytes, higher numbers of follicles and better in vitro fertilization outcomes (13).

In this clinical trial we have found out that the miscarriage rate in the BRM group was lower than the long protocol group. Jinno et al have not addressed the rate of miscarriage in their work. Despite the similarity of number of oocytes retrieved and quality of embryos, the decline in miscarriage might be due to a better endometrial receptivity. The findings of our study confirm a good endometrial receptivity which is more likely to be through improved endometrial prolactin system. In a pilot study, Garzia et al have reported that a defect in endometrial prolactin production could result in unexplained infertility and repeated miscarriages.

The mean age of patients in this study was 7 and 6 years lesser compared to Jinno et al (10), which might explain the better outcomes of our study. The mentioned studies had been conducted on IVF failure while the current study included other patients which were not IVF failures.

The results and comments in this work have been limited as the studied population was 114 women based on feasibility. The project could not recruit more volunteers and hence the results should be interpreted with caution. The findings of this study seem to open a new path toward understanding the endometrial receptivity, since it has a critical role in declining miscarriage in group of patients on BRM. However, the mechanism by which the miscarriage rate declines is still in need of explanation.

CONCLUSION

This prospective study has demonstrated that BRM might lead to higher ongoing pregnancy and live birth rates compared to long protocol in women undergoing ICSI cycles.

CONFLICT OF INTEREST

None declared.

REFERENCES

1. Gnoth C, Maxrath B, Skonieczny T, Friol K, Godehardt E, Tigges J. Final ART success rates: a 10 years survey. Hum Reprod 2011;26: 2239-46.
2. Bosch E, Ezcurra D. Individualized controlled ovarian stimulation (icos): maximizing success rates for assisted reproductive technology patients. Reprod Biol Endocrinol 2011; 21: 82-6.
3. Shapiro BS, Daneshmand ST, Garner FC, Aguirre M, Hudson C, Thomas S. Evidence of impaired endometrial receptivity after ovarian stimulation for in vitro fertilization: a prospective randomized trial comparing fresh and frozen-thawed embryo transfer in normal responders. Fertil Steril 2011; 96: 344-8.
4. McNeilly AS: Prolactin and ovarian function. Muller EE, Macleod RM, Neuroendocrine perspectives 1984; 279-319.
5. Oda T, Yoshimura Y, Takehara Y, et al. Effects of prolactin on fertilization and cleavage of human oocytes. Horm Res 1991; 35: 33-8.
6. Kiapekou E, Loutradis D, Mastorakos G, Bletsa R, Beretsos P, Zapanti E, Drakakis P, Antsaklis A, Kiessling AA. Effect of prolactin on in vitro follicle growth, in vitro oocyte maturation, fertilization and early embryonic development in mice. Cloning Stem Cells 2009; 11:293-300.
7. Ozaki T, Takahashi k, kurioka H, Miyazaki k. Influence of midluteal serum prolactin on outcome of pregnancy after IVF-EI: a preliminary study. J Assist Reprod Genet 2001; 18 (7): 387-90.
8. Jinno M, Ubukata Y, Satou M, Katsumata Y, Yoshimura Y, Nakamura Y, et al. A novel method of ovarian stimulation for in vitro fertilization (bromocriptine rebound method) increases developmental potential of oocytes and pregnancy rate. Nippon Sanka Fujinka Gakkai Zasshi 1995; 47 (12): 1337-44.
9. World Health Organization. WHO laboratory manual for the examination of human semen and semen-cervical mucus interaction 4^th ed. Cambridge: Cambridge University Press; 1999.
10. Jinno M, Yoshimura Y, Ubukata Y, Nakamura Y. A novel method of ovarian stimulation for in vitro fertilization: bromocriptine rebound method. Fertil steril 1996; 66 (2) : 271-4.
11. Jinno M, Katsumata Y, Hoshiai T, Nakamura Y, Matsumoto K, Yoshimura Y. A therapeutic role of prolactin supplementation in ovarian stimulation for in vitro fertilization: the bromocriptine rebound method. J clin Endocrinol Metab 1997; 82 (11) : 3603-11.
12. Moride N, Kuwahara A, Yamashita M, Tanaka Y, et al. Does the bromocriptine-rebound method improve embryo quality? J Med Invest. 2011; 58: 63-6.
13. Mendes MC, Ferriani RA, Sala MM, Moura MD, Carrara HH, and de Sa MF. Effect of transitory hyperprolactinemia on in vitro fertilization of human oocytes. J Reprod Med 2001; 46(5): 444-50.

Table 1: Patient and cycle characteristics and pregnancy outcomes of both groups (BRM and long protocol)

^a values are mean ± SD

^b value is median (range)

^c No. of 75IU ampoules

Table 2: Basic laboratory findings among patients in both BRM and long protocol groups, the data has been expressed as mean ± SD

^a values are mean ± SD

Figure Legends

Figure 1: Flowchart of the presented clinical trial