Serum inhibin B levels measured early during FSH administration for IVF may be of value in predicting the number of oocytes to be retrieved in normal and low responders

T. Eldar-Geva1,2,5, E.J. Margalioth1, A. Ben-Chetrit1, M. Gal1, D.M. Robertson3, D.L. Healy4, Y.Z. Diamant1 and I.M. Spitz2

1 IVF Unit, Department of Obstetrics and Gynecology, 2 Institute of Hormone Research Shaare-Zedek Medical Center, Ben-Gurion University, P.O.Box 3235, Jerusalem 91031, Israel, 3 Prince Henry's Institute of Medical Research and 4 Department of Obstetrics and Gynaecology, Monash Medical Centre, Melbourne, Victoria, Australia


    Abstract
 Top
 Abstract
 Introduction
 Materials and methods
 Results
 Discussion
 Acknowledgements
 References
 
BACKGROUND: In a previous study we have found that in normal ovulatory women, serum inhibin B levels on days 4–6 of FSH administration correlated with the number of oocytes retrieved. In the current study we examined the significance of earlier inhibin B measurements in predicting the oocyte number, in both normal and low responders. METHODS: Study A consisted of 19 patients undergoing their first IVF cycle (n = 10) or had a normal response (6 oocytes retrieved, n = 9), while study B consisted of 15 patients with a previous low ovarian response (<=5 oocytes retrieved). All patients had day 3 FSH levels <10 IU/l. After pituitary suppression, 300 (study A) or 600 IU (study B) of pure FSH was administered daily. Serum FSH, inhibin A, inhibin B and estradiol (E2) were determined prior to and every 1–2 days throughout FSH treatment. RESULTS: Study A: oocyte number between 4 and 14 correlated significantly with serum inhibin B levels on all days of FSH treatment, and with inhibin A and E2 late during treatment. No correlation was found between inhibin B and when oocyte number was >16. Study B: oocyte number correlated significantly with inhibin B and inhibin A on all days of FSH treatment, even on day 2 (r = 0.90, P < 0.001 and r = 0.65, P < 0.05 for inhibin B and A respectively). No significant correlation was found with E2 levels. In both studies, all patients with inhibin B >100 pg/ml on treatment day 2 had >6 oocytes. CONCLUSIONS: Our data suggest that serum inhibin B measured early during FSH stimulation may indicate whether sufficient oocytes will be retrieved, in both normal and low responders. Serum inhibin B measured during early FSH treatment may be of predictive value in monitoring ovarian stimulation treatment for IVF.

Key words: inhibin A/inhibin B/IVF/low responders/oocyte number


    Introduction
 Top
 Abstract
 Introduction
 Materials and methods
 Results
 Discussion
 Acknowledgements
 References
 
Inhibin A and inhibin B are secreted from granulosa cells following FSH stimulation, and regulate FSH secretion by negative feedback (Vale et al., 1990Go; Baird and Smith, 1993Go). Inhibin B is produced mainly by small antral follicles whereas inhibin A is a product of the dominant follicle and the corpus luteum (Lockwood et al., 1998Go). Levels of both inhibin A and inhibin B rose markedly during FSH stimulation (Muttukrishna et al., 1994Go; Lockwood et al., 1996Go; Eldar-Geva et al., 2000Go; Casper et al., 2001Go).

The ageing of the ovary is accompanied by depletion of primordial and antral follicles (Faddy and Gosden, 1996Go) and a decrease in inhibin B secretion (Klein et al., 1996Go; Danforth et al., 1998Go). Early follicular phase serum inhibin B may be a suitable marker of ovarian follicle reserve and fertility potential (Klein et al., 1996Go; Seifer et al., 1997Go, 1999Go; Danforth et al., 1998Go). However, several studies found no or limited clinical value in measuring basal early follicular inhibin B with regard to IVF outcome (Corson et al., 1999Go; Hall et al., 1999Go; Tinkanen et al., 1999Go; Creus et al., 2000Go; Ravhon et al., 2000Go; Dumesic et al., 2001Go).

It was found that inhibin B level on day 5 of FSH treatment for IVF was highly predictive of ovarian response (Penarrubia et al., 2000Go). Another study (Dokras et al., 2000Go) observed that inhibin B levels on treatment days 8 to 11 was lower in patients with endometriosis and correlated with the number of oocytes retrieved. Recently, the increment in serum inhibin B 24 h after FSH stimulation in the early follicular phase of the preceding cycle was found to be correlated with the number of follicles in normal cycling women and in women with polycystic ovarian syndrome (PCOS) (Elting et al., 2001Go).

In a previous study, we found that following a daily fixed dose administration of FSH, in normal ovulatory young women, serum inhibin B after 4–6 days of FSH treatment significantly correlated with the number of oocytes retrieved (r = 0.89, P < 0.001) (Eldar-Geva et al., 2000Go). Other markers used for monitoring ovarian response [estradiol (E2) and follicular number and size] could not predict treatment outcome at this early stage of treatment. The aims of the current study were to examine the significance of earlier inhibin B measurements in predicting the number of oocytes to be retrieved and to assess whether a similar relationship between inhibin B and oocyte number applies to patients with low ovarian response.


    Materials and methods
 Top
 Abstract
 Introduction
 Materials and methods
 Results
 Discussion
 Acknowledgements
 References
 
Subjects
Thirty-four women undergoing IVF treatment between March 1999 and March 2000 in the IVF Unit in Shaare-Zedek Medical Center were included in the studies. All patients had day 3 FSH serum concentrations <10 IU/l, normal ovulatory cycles with a mean length of between 24 and 35 days, a body mass index (BMI) between 18 and 27 kg/m2 and were in good physical and mental health. Patients with endocrine abnormalities such as hyperprolactinaemia, PCOS or thyroid dysfunction, or ovarian cysts >2 cm in diameter were excluded. The Shaare-Zedek Medical Center Research and Ethics Committee, Jerusalem, approved the study protocol. Informed consent was obtained from all participants.

Study A
Nineteen patients either undergoing their first IVF cycle (10 patients) or who had normal response (>=6 oocytes retrieved, nine patients) in their previous cycles were included in this study. The patients were treated with the long down-regulation protocol consisting of decapeptyl [0.1 mg/day; Ferring Ltd (A.Lapidot Ltd), Herzliya, Israel] s.c. for 14 days, starting in the mid-luteal phase of the ovarian cycle. When E2 concentrations were <150 pmol/l and the presence of any ovarian cysts was excluded by vaginal ultrasound, a fixed daily dose of 300 IU of pure FSH (Metrodin, 75 IU/ampoule; Teva, Petah Tikva, Israel) was administered i.m. Serum samples were collected prior to, and every 1–2 days throughout, FSH treatment. For the convenience of both the patients and the clinicians, FSH injections were self-administered every day at 20:00 and blood samples were taken at 08:00. The ovarian response was monitored by serum E2 and transvaginal ultrasonography. Serum samples were stored at –20°C until assayed for progesterone, FSH, LH, inhibin A and inhibin B. Treatment was continued for a maximum of 3 weeks until two or more follicles >17 mm developed. hCG (10 000 IU, Chorigon; Teva) was given to promote ovulation. Oocytes were retrieved transvaginally 36 h later under general anaesthesia. Routine IVF or ICSI and embryo culture were used as indicated and a maximum of three embryos were transferred 2–3 days following oocyte retrieval.

Study B
Fifteen patients with previous low ovarian response (<=5 oocytes retrieved) to the ordinary FSH treatment dose (300 IU/day) were included in this study. They were also treated with the above long down-regulation protocol; however, a higher daily FSH dose (600 IU) was used. Clinical data of both groups are presented in Table IGo.


View this table:
[in this window]
[in a new window]
 
Table I. Characteristics of the patients in the two studies (mean ± SEM)
 
Hormone assays
Serum concentrations of E2, progesterone, LH, FSH and prolactin were measured using a chemiluminescent immunoassay (Diagnostic Products Corporation, Los Angeles, CA, USA). The inter- and intra-assay coefficients of variation were respectively 9.2 and 4.9% for E2, 12.3 and 9.2% for progesterone, 7.8 and 1.9% for LH, 4.3 and 3.6% for FSH and 3.7 and 1.7% for prolactin. Serum inhibin A and inhibin B concentrations were measured using a highly sensitive two-site ELISA (Serotec, Oxford, UK). The specificity and validity of the inhibin A and B assays have been previously reported (Groome et al., 1996Go). The standards (supplied as parts of the commercial kits) were prepared by extracting a mixture of inhibin forms from human follicular fluid and the concentration was determined by calibration against recombinant 32 kDa inhibin A and B respectively. The assay sensitivity was 2 and 15 pg/ml for inhibin A and B respectively. The inter-assay variations were 8 and 15% respectively.

Statistical analysis
Samples with hormone values below the assay detection limit were assigned values equal to the detection limit of that assay. Statistical analysis was performed using Mann–Whitney U-test and Pearson's correlation coefficient as appropriate. Results are expressed as means ± SEM unless otherwise indicated. Differences were considered to be statistically significant if P < 0.05.


    Results
 Top
 Abstract
 Introduction
 Materials and methods
 Results
 Discussion
 Acknowledgements
 References
 
Study A
The characteristics and outcome of the treatment cycle are given in Table IIGo. All patients fulfilled the criteria for hCG administration. The median number of oocytes retrieved was 15 (range 4–22). Embryo transfer followed in all cycles. None of the patients had signs or symptoms of ovarian hyperstimulation syndrome (OHSS).


View this table:
[in this window]
[in a new window]
 
Table II. Characteristics of the treatment cycle in the two studies(mean ± SEM)
 
To investigate the ability of serum hormone levels during early FSH treatment to predict the treatment outcome, correlation coefficients were determined between the number of oocytes retrieved and serum inhibin A, inhibin B and E2 determined before commencing FSH treatment (day 0), 12 h after the second dose administration (day 2) and thereafter every 24–48 h throughout FSH treatment (Table IIIGo). The correlations between serum inhibin B or inhibin A after pituitary suppression for 2 weeks with GnRH analogue (day 0) and the number of oocytes retrieved were not significant. Correlation with serum E2 could not be applicable because most patients' serum levels were below the assay sensitivity (<150 pmol/l). Significant correlations were found between the number of oocytes retrieved and serum inhibin B concentration on all days of FSH treatment (r = 0.62–0.77; P < 0.05–0.001), even 36 h after commencing FSH treatment (day 2). Serum inhibin A and E2 showed significant correlations with oocyte number later in the treatment period. The highest correlations were observed with inhibin A late in the treatment period (days 5–6 until the last day; r = 0.80–0.90, P < 0.01–0.001).


View this table:
[in this window]
[in a new window]
 
Table III. Correlation between the number of oocytes retrieved and serum inhibin A, inhibin B and estradiol (E2) during FSH treatment
 
Figure 1Go shows the correlation between oocyte number and serum inhibin B on day 2 of FSH treatment. All patients with serum inhibin B of >100 pg/ml had >6 oocytes. Although there was a significant linear (Pearson's) correlation between serum inhibin B and the number of oocytes in the range 3–16 oocytes (r = 0.94; n = 7; P < 0.001), the best regression line for the whole group was not linear (Figure 1Go). No correlation was found between inhibin B and oocyte number >16. Figure 1Go shows the wide range of day 2 serum inhibin B (150–706 pg/ml) for patients with 19–22 oocytes.



View larger version (15K):
[in this window]
[in a new window]
 
Figure 1. Study A: correlation between the number of oocytes retrieved and serum inhibin B levels on day 2 of FSH treatment. The linear regression line represents the correlation for patients with <16 oocytes. The curved line represents the regression line for the whole group.

 
Study B
The characteristics and outcome of the treatment cycle are given in Table IIGo. All patients had oocyte retrieval. The median number of oocytes retrieved was 5 (range 0–13). This was despite a double daily dose of FSH administration to patients in this study (600 IU) compared with study A (300 IU). Embryo transfer followed in 13 cycles (range 1–5 embryos).

The correlation between the number of oocytes retrieved and serum inhibin B and inhibin A were significant on all days of FSH treatment (Table IIIGo). Highly significant correlations were noted with inhibin B early during treatment (r = 0.85–0.90 on days 2, 3 and 4). Significant, but lower, correlations were found with inhibin A on days 2 and 3 of FSH treatment (r = 0.65–0.68; P < 0.05). Highly significant correlations were found with inhibin A late during FSH treatment (r = 0.86–0.94; P < 0.001 from days 5–6 until the last day). No significant correlations were observed between oocyte number and serum E2 levels on any day of treatment.

The regression line for day 2 was linear for a large range of oocyte numbers (0–13) (Figure 2Go). Similar to the results of study A, all patients with serum inhibin B >100 pg/ml had >6 oocytes.



View larger version (16K):
[in this window]
[in a new window]
 
Figure 2. Study B: correlation between the number of oocytes retrieved and serum inhibin B levels on day 2 of FSH treatment.

 
Both studies
The time courses of the various hormone serum concentrations during FSH treatment in the two studies are shown in Figure 3Go. Serum inhibin B concentrations increased from day 2 of FSH treatment to reach a maximum by day 6–7 in study A and by day 4–5 in study B. Serum inhibin B concentrations were lower in study B compared with study A all through FSH treatment. These differences were statistically significant (P < 0.05–0.005) from day 4–5 of FSH treatment. By contrast, serum E2 and inhibin A concentrations showed a continuous increase from day 4–5 but were not significantly different between the two studies except for the last day (P < 0.01). Serum FSH concentrations increased steadily from day 2 of treatment to reach a plateau by day 4–5. Serum FSH levels were significantly lower in study A (daily FSH dose 300 IU) compared with study B (daily FSH dose 600 IU) (P < 0.05 to P < 0.001).



View larger version (11K):
[in this window]
[in a new window]
 
Figure 3. Time course of serum hormone concentrations during FSH treatment in study A (•) and study B ({blacksquare}). Day 0 samples were obtained after pituitary suppression was achieved and before the first FSH dose. *P < 0.05; **P < 0.01; ***P < 0.005.

 

    Discussion
 Top
 Abstract
 Introduction
 Materials and methods
 Results
 Discussion
 Acknowledgements
 References
 
Previous studies have proposed that evaluation of ovarian reserve and prediction of assisted reproduction treatment outcome could be accomplished by determining serum FSH (Scott et al., 1989Go; Toner et al., 1991Go) and E2 (Smotrich et al., 1995Go) on day 3 of a non-treatment cycle. However, normogonadotrophic normogonadal women may have suboptimal ovarian response to FSH stimulation (Farhi et al., 1997Go). Day 3 FSH and E2 show significant intercycle variability (Scott et al., 1990Go; Hansen et al., 1996Go). Thirty-five percent of patients may have normal or intermediate range levels during one cycle and elevated levels in another. These patients respond poorly to ovarian stimulation (Scott et al., 1990Go). An additional problem is that high E2 and progesterone levels during the luteal phase may influence the subsequent early follicular FSH levels (Lahlou et al., 1999Go). Therefore, the test may be less accurate when performed after induction of superovulation or after luteal support with progesterone or estrogen. Some studies have demonstrated that early follicular inhibin B can serve as a better and direct measure of ovarian reserve (Seifer et al., 1997Go; Hofmann et al., 1998Go). However, others found limited clinical value for basal inhibin B testing with regards to assisted reproductive treatment outcome (Corson et al., 1999Go; Hall et al., 1999Go; Tinkanen et al., 1999Go; Ravhon et al., 2000Go; Dumesic et al., 2001Go). The main disadvantage of these methods is that although the predictive value of the tests is high when the results are abnormal, the sensitivity is low.

Provocative tests such as the clomiphene citrate challenge test (CCCT) (Navot et al., 1987Go) have been shown to be more sensitive than screening with basal day 3 FSH alone, in both the general infertility population and in assisted reproduction patients (Loumaye et al., 1990Go; Tanbo et al., 1992Go; Scott et al., 1993Go). Determining E2 response in the GnRH agonist stimulation test (Garcia et al., 1990Go; Padilla et al., 1990Go; Galtier-Dereure et al., 1996Go; Ranieri et al., 1998Go) or the exogenous FSH ovarian reserve test (EFORT) (Fanchin et al., 1994Go) seem to improve the predictive value of the basal hormone levels. Previous studies (Ravhon et al., 2000Go) have shown that inhibin B and E2 dynamic changes after GnRH analogue administration on cycle day 2 correlated with ovarian response for IVF and were superior to basal hormones levels. Other investigators (Dzik et al., 2000Go) have reported that low inhibin B response to EFORT could predict low ovarian response in a subsequent IVF cycle and that E2 response was less informative. Elting et al. showed that the rise of E2 and inhibin B after FSH stimulation in the follicular phase predicts the number of follicles in patients with polycystic ovaries and in young, normal menstruating women (Elting et al., 2001Go). Fabregues et al. found that after 5 days of hMG stimulation, serum E2, but not inhibin B level, was a better predictor of ovarian response than basal FSH, inhibin B and E2 levels (Fabregues et al., 2000Go). These studies support the assumption that dynamic changes in ovarian hormones could be more sensitive than basal hormone measurement in predicting assisted reproduction outcome. However, dynamic tests performed before the treatment cycle have some disadvantages. A high percentage of cycle-to-cycle variability may change the prognostic value of the CCCT in up to 40% of patients (Hannoun et al., 1998Go).

In a previous study, we found that in normal ovulatory young women treated with pituitary suppression and a daily fixed dose of FSH, serum inhibin B after 4–6 days of FSH treatment significantly correlated with the number of oocytes retrieved (Eldar-Geva et al., 2000Go). Other investigators found similar correlations after 5 (Penarrubia et al., 2000Go) or 8–10 days (Dokras et al., 2000Go) of FSH treatment. The current study shows that in patients with either low or normal ovarian reserve, serum inhibin B levels measured as early as 36 h after commencing FSH treatment (day 2) may indicate whether sufficient oocytes will be collected 10–16 days later. In the group of patients with previous low ovarian response, day 2 inhibin B levels could predict the number of oocytes to be retrieved.

The crucial parameter determining the number of oocytes retrieved is the extent of the cohort of recruited healthy very small follicles. The size of this cohort may change from cycle to cycle (Scheffer et al., 1999Go), especially in elderly patients. We assume that the hormone level intercycle variability represents different cohort sizes at different cycles. The high correlation observed in our study between serum inhibin B levels very early during FSH treatment and subsequent number of oocytes collected in patients with previous low ovarian response, suggests that the measurement of inhibin B may be useful as a marker of ovarian response during early FSH treatment on a specific treatment cycle and under a specific FSH dose in this group of patients.

Our findings might have a clinical implication, although larger studies are needed. For example, in both studies, all patients with day 2 serum inhibin B >100 pg/ml had >6 oocytes retrieved (Figures 1 and 2GoGo). Only one patient (Figure 2Go) with serum inhibin B <100 pg/ml had >6 oocytes retrieved. This information might be used for reassuringly advising patients with day 2 inhibin B >100 pg/ml to continue the treatment cycle with the same initial daily FSH dose. Patients with day 2 inhibin B <100 pg/ml might be advised either to change the FSH or the GnRH analogue dose, or perhaps to cancel the treatment cycle. Our ability to change treatment outcome late during the course of treatment is limited. Very early during treatment, increasing FSH levels may facilitate the recruitment of more follicles. It is still to be clarified whether modulating FSH or GnRH analogue doses early during FSH treatment would improve outcome. Nevertheless, even if the doctor and/or the patients prefer to cancel the cycle, the earlier this is done the better.

Our results showed that predicting the oocyte number was less effective in high responders, i.e. patients who had >15 oocytes had very wide range of day 2 serum inhibin B (Figure 1Go). None of these patients had PCOS or OHSS. We assume that repeated FSH doses may continuously recruit ovarian follicles in these patients, while in the low or normal responders (<15 oocytes retrieved) the continuous recruitment is limited. Indeed, serum inhibin B concentrations reached the maximum later in study A than in study B (Figure 3Go).

In study A, inhibin A, and to a lesser extent E2 levels, correlated with the number of oocytes retrieved. In contrast, in study B, although highly significant correlations were found with inhibin A late during treatment, no correlation was found with E2 levels on any day of the treatment (Table IIIGo). Dokras et al. observed similar results in patients with endometriosis and low ovarian response, compared with patients with tubal factor infertility and normal response (Dokras et al., 2000Go). A decrease in inhibin B is the earliest marker of the decline in follicle number across reproductive ageing (Seifer et al., 1999Go; Welt et al., 1999Go). E2 secretion decreases later during ovarian ageing. The patients in our studies, especially in study B, may represent different stages of ovarian ageing. Hence, E2 response to FSH is useless as a marker for ovarian response in this heterogeneous group of patients.

Our study is the first to determine serial changes in serum inhibins throughout FSH treatment in normal and low responders. In agreement with previous pharmacodynamic studies (le Contonnec et al., 1994Go), we found that serum FSH level after daily administration at either of two fixed doses (300 or 600 IU) resulted in stable serum FSH concentrations from day 3–5. In our previous study and those of others, on patients with normal ovarian response (Lockwood et al., 1998Go; Eldar-Geva et al., 2000Go), the maximal inhibin B response was observed 2–3 days later. The current study shows that in patients with low ovarian response (study B), serum inhibin B concentrations stabilized earlier, even before FSH achieved its maximal levels (Figure 3Go). Patients with very low oocyte number had almost no change in serum inhibin B levels throughout treatment. In contrast, in patients with normal ovarian response (study A) the time course of inhibin B was similar to the course of FSH. This difference may represent suboptimal inhibin B secretion from small and medium size follicles in the patients from study B. Another possibility is that recruitment of follicles continues beyond the first days of FSH stimulation in the patients from study A, but not in study B.

In conclusion, serum inhibin B levels determined during the early stages (e.g. after two or three daily doses) of FSH treatment provide an early indication of the number of recruited follicles which are destined to form mature oocytes and indicates those patients in whom a reasonable response will be achieved and sufficient oocytes will be retrieved. It seems that serum inhibin B is a better predictor of the number of oocytes retrieved than serum E2 or inhibin A levels. Both the patients and the clinician may use this information in making decisions regarding cancellation of a cycle or, perhaps, modulating the FSH or the GnRH agonist doses.


    Acknowledgements
 Top
 Abstract
 Introduction
 Materials and methods
 Results
 Discussion
 Acknowledgements
 References
 
The authors are grateful to Yanek Hyatt, MSc, for the statistical analysis of the results and to the nursing and secretary staff of the IVF Unit in Shaare-Zedek Medical Center for their assistance.


    Notes
 
5 To whom correspondence should be addressed at: IVF Unit, Shaare-Zedek Medical Center, Ben-Gurion University, P.O.Box 3235, Jerusalem 91031, Israel. E-mail: gevat{at}szmc.org.il Back


    References
 Top
 Abstract
 Introduction
 Materials and methods
 Results
 Discussion
 Acknowledgements
 References
 
Baird, D.T. and Smith, K.B. (1993) Inhibin and related peptides in the regulation of reproduction. Oxf. Rev. Reprod. Biol., 15, 191–232.[Medline]

Casper, F.W., Seufert, R.J., Schaffrath, M. and Pollow, K. (2001) Concentrations of inhibins and activin in women undergoing stimulation with recombinant follicle-stimulating hormone for in vitro fertilization treatment. Fertil. Steril., 75, 32–37.[ISI][Medline]

Corson, S.L., Gutmann, J., Batzer, F.R., Wallace, H., Klein, N. and Soules, M.R. (1999) Inhibin-B as a test of ovarian reserve for infertile women. Hum. Reprod., 14, 2818–2821.[Abstract/Free Full Text]

Creus, M., Penarrubia, J., Fabregues, F., Vidal, E., Carmona, F., Casamitjana, R., Vanrell, J.A. and Balasch, J. (2000) Day 3 serum inhibin B and FSH and age as predictors of assisted reproduction treatment outcome. Hum. Reprod., 15, 2341–2346.[Abstract/Free Full Text]

Danforth, D.R., Arbogast, L.K., Mroueh, J., Kim, M.H., Kennard, E.A., Seifer, D.B. and Friedman, C.I. (1998) Dimeric inhibin: a direct marker of ovarian aging. Fertil. Steril., 70, 119–123.[ISI][Medline]

Dokras, A., Habana, A., Giraldo, J. and Jones, E. (2000) Secretion of inhibin B during ovarian stimulation is decreased in infertile women with endometriosis. Fertil. Steril., 74, 35–40.[ISI][Medline]

Dumesic, D.A., Damario, M.A., Session, D.R., Famuyide, A., Lesnick, T.G., Thornhill, A.R. and McNeilly, A.S. (2001) Ovarian morphology and serum hormone markers as predictors of ovarian follicle recruitment by gonadotropins for in vitro fertilization. J. Clin. Endocrinol. Metab., 86, 2538–2543.[Abstract/Free Full Text]

Dzik, A., Lambert-Messerlian, G., Izzo, V.M., Soares, J.B., Pinotti, J.A. and Seifer, D.B. (2000) Inhibin B response to EFORT is associated with the outcome of oocyte retrieval in the subsequent in vitro fertilization cycle. Fertil. Steril., 74, 1114–1117.[ISI][Medline]

Eldar-Geva, T., Robertson, D.M., Cahir, N., Groome, N., Gabbe, M.P., Maclachlan, V. and Healy, D.L. (2000) Relationship between serum inhibin A and B and ovarian follicle development following a daily fixed dose administration of recombinant FSH. J. Clin. Endocrinol. Metab., 85, 607–613.[Abstract/Free Full Text]

Elting, M.W., Kwee, J., Schats, R., Rekers-Mombarg, L.T. and Schoemaker, J. (2001) The rise of estradiol and inhibin B after acute stimulation with follicle-stimulating hormone predict the follicle cohort size in women with polycystic ovary syndrome, regularly menstruating women with polycystic ovaries, and regularly menstruating women with normal ovaries. J. Clin. Endocrinol. Metab., 86, 1589–1595.[Abstract/Free Full Text]

Faddy, M.J. and Gosden, R.G. (1996) A model conforming the decline in follicle numbers to the age of menopause in women. Hum. Reprod., 11, 1484–1486.[Abstract/Free Full Text]

Fabregues, F., Balasch, J., Creus, M., Carmona, F., Puerto, B., Quinto, L,. Casamitjana, R. and Vanrell, J.A. (2000) Ovarian reserve test with human menopausal gonadotropin as a predictor of in vitro fertilization. J. Assist. Reprod. Genet., 17, 13–19.[ISI][Medline]

Fanchin, R., de Ziegler, D., Olivennes, F., Taieb, J., Dzik, A. and Frydman, R. (1994) Exogenous follicle stimulating hormone ovarian reserve test (EFORT): a simple and reliable screening test for detecting `poor responders' in in-vitro fertilization. Hum. Reprod., 9, 1607–1611.[Abstract]

Farhi, J., Homburg, R., Ferber, A., Orvieto, R. and Ben Rafael, Z. (1997) Non-response to ovarian stimulation in normogonadotrophic, normogonadal women: a clinical sign of impending onset of ovarian failure pre-empting the rise in basal follicle stimulating hormone levels. Hum. Reprod., 12, 241–243.[Abstract]

Galtier-Dereure, F., De-Bouard, V., Picto, M.C., Vergnes, C., Humeau, C., Bringer, J. and Hedon, B. (1996) Ovarian reserve test with the gonadotrophin-releasing hormone agonist buserelin: correlation with in-vitro fertilization outcome. Hum. Reprod., 11, 1393–1398.[Abstract/Free Full Text]

Garcia, J.E., Padilla, S.L., Bayati, J. and Baramki, T.A. (1990) Follicular phase gonadotropin-releasing hormone agonist and human gonadotropins: a better alternative for ovulation induction in in vitro fertilization. Fertil. Steril., 53, 302–305.[ISI][Medline]

Groome, N.P., Illingworth, P.J., O'Brien, M., Pai, R., Rodger, F.E., Mather, J.P. and McNeilly, A.S. (1996) Measurement of dimeric inhibin B throughout the human menstrual cycle. J. Clin. Endocrinol. Metab., 81, 1401–1405.[Abstract]

Hall, J.E., Welt, C.K. and Cramer, D.W. (1999) Inhibin A and inhibin B reflect ovarian function in assisted reproduction but are less useful at predicting outcome. Hum. Reprod., 14, 409–415.[Abstract/Free Full Text]

Hannoun, A., Abu Musa, A., Awwad, J., Kaspar, H. and Khalil, A. (1998) Clomiphene citrate challenge test: cycle to cycle variability of cycle day 10 follicle stimulating hormone level. Clin. Exp. Obstet. Gynecol., 25, 155–156.[Medline]

Hansen, L.M., Batzer, F.R., Gutmann, J.N., Corson, S.L., Kelly, M.P. and Gocial, B. (1996) Evaluating ovarian reserve: follicle stimulating hormone and oestradiol variability during cycle days 2–5. Hum. Reprod., 11, 486–489.[Abstract]

Hofmann, G.E., Danforth, D.R. and Seifer, D.B. (1998) Inhibin-B: the physiologic basis of the clomiphene citrate challenge test for ovarian reserve screening. Fertil. Steril., 69, 474–477.[ISI][Medline]

Klein, N.A., Illingworth, P.J., Groome, N.P., McNeilly, A.S., Battaglia, D.E. and Soules, M.R. (1996) Decreased inhibin B secretion is associated with the monotropic FSH rise in older, ovulatory women: a study of serum and follicular fluid levels of dimeric inhibin A and B in spontaneous menstrual cycles. J. Clin. Endocrinol. Metab., 81, 2742–2745.[Abstract]

Lahlou, N., Chabbert-Buffet, N., Christin-Maitre, S., Le Nestour, E., Roger, M. and Bouchard, P. (1999) Main inhibitor of follicle stimulation hormone in the luteal–follicular transition: inhibin A, or inhibin B? Hum. Reprod., 14, 1190–1193.[Abstract/Free Full Text]

le Contonnec, J.Y., Porchet, H.C., Beltrami, V., Khan, A., Toon, S. and Rowland, M. (1994) Clinical pharmacology of recombinant human follicle-stimulating hormone. II. Single doses and steady state pharmacokinetics. Fertil. Steril., 61, 679–686.[ISI][Medline]

Lockwood, G.M., Muttukrishna, S., Groome, N.P., Knight, P.G. and Ledger, W.L. (1996) Circulating inhibins and activin A during GnRH-analogue down-regulation and ovarian hyperstimulation with recombinant FSH for in-vitro fertilization–embryo transfer. Clin. Endocrinol., 45, 741–748.[ISI][Medline]

Lockwood, G.M., Muttukrishna, S. and Ledger, W.L. (1998) Inhibins and activins in human ovulation, conception and pregnancy. Hum. Reprod. Update, 4, 284–295.[Abstract/Free Full Text]

Loumaye, E., Billion, J.M., Mine, J.M., Psalti, I., Pensis, M. and Thomas, K. (1990) Prediction of individual response to controlled ovarian hyperstimulation by means of a clomiphene citrate challenge test. Fertil. Steril., 53, 295–301.[ISI][Medline]

Muttukrishna, S., Fowler, P.A., Groome, N.P., Mitchell, G.G., Robertson, W.R. and Knight, P.G. (1994) Serum concentrations of dimeric inhibin during the spontaneous human menstrual cycle and after treatment with exogenous gonadotrophin. Hum. Reprod., 9, 1634–1642.[Abstract]

Navot, D., Rosenwaks, Z. and Margalioth, E.J. (1987) Prognostic assessment of female fecundity. Lancet, ii, 645–647.

Padilla, S.L., Bayati, J. and Garcia, J.E. (1990) Prognostic value of the early serum estradiol response to leuprolide acetate in in vitro fertilization. Fertil. Steril., 53, 288–294.[ISI][Medline]

Penarrubia, J., Balasch, J., Fabregues, F., Carmona, F., Casamitjana, R., Moreno, V., Calafell, J.M. and Vanrell, J.A. (2000) Day 5 inhibin B serum concentrations as predictors of assisted reproductive technology outcome in cycles stimulated with gonadotrophin-releasing hormone agonist-gonadotrophin treatment. Hum. Reprod., 15, 1499–1504.[Abstract/Free Full Text]

Ranieri, D.M., Quinn, F., Makhlouf, A., Khadum, I., Ghutmi, W., McGarrigle, H., Davies, M. and Serhal, P. (1998) Simultaneous evaluation of basal follicle-stimulating hormone and 17 beta-estradiol response to gonadotropin-releasing hormone analogue stimulation: an improved predictor of ovarian reserve. Fertil. Steril., 70, 227–233.[ISI][Medline]

Ravhon, A., Lavery, S., Michael, S., Donaldson, M., Margara, R., Trew, G. and Winston, R. (2000) Dynamic assays of inhibin B and oestradiol following buserelin acetate administration as predictors of ovarian response in IVF. Hum. Reprod., 15, 2297–2301.[Abstract/Free Full Text]

Scheffer, G.J., Broekmans, F.J.M., Dorland, M., Habbema, J.D., Looman, C.W. and te Velde, E.R. (1999) Antral follicle counts by transvaginal ultrasonography are related to age in women with proven natural fertility. Fertil. Steril., 72, 845–851.[ISI][Medline]

Scott, R.T., Toner, J.P., Muasher, S.J., Oehninger, S., Robinson, S. and Rosenwaks, Z. (1989) Follicle-stimulating hormone levels on cycle day 3 are predictive of in vitro fertilization outcome. Fertil. Steril., 51, 651–654.[ISI][Medline]

Scott, R.T., Hofmann, G.E., Oehninger, S. and Muasher, S.J. (1990) Intercycle variability of day 3 follicle-stimulating hormone levels and its effect on stimulation quality in in vitro fertilization. Fertil. Steril., 54, 297–302.[ISI][Medline]

Scott, R.T., Leonardi, M.R., Hofmann, G.E., Illions, E.H., Neal, G.S. and Navot, D. (1993) A prospective evaluation of clomiphene citrate challenge test screening of the general infertility population. Obstet. Gynecol., 82, 539–544.[Abstract]

Seifer, D.B., Lambert Messerlian, G., Hogan, J.W., Gardiner, A.C., Blazar, A.S. and Berk, C.A. (1997) Day 3 serum inhibin-B is predictive of assisted reproductive technologies outcome. Fertil. Steril., 67, 110–114.[ISI][Medline]

Seifer, D.B., Scott, R.T., Jr, Bergh, P.A., Abrogast, L.K., Friedman, C.I., Mack, C.K. and Danforth, D.R. (1999) Women with declining ovarian reserve may demonstrate a decrease in day 3 serum inhibin B before a rise in day 3 follicle-stimulating hormone. Fertil. Steril., 72, 63–65.[ISI][Medline]

Smotrich, D.B., Widra, E.A., Gindoff, P.R., Levy, M.J., Hall, J.L. and Stillman, R.J. (1995) Prognostic value of day 3 estradiol on in vitro fertilization outcome. Fertil. Steril., 64, 1136–1140.[ISI][Medline]

Tanbo, T., Dale, P.O., Lunde, O., Norman, N. and Abyholm, T. (1992) Prediction of response to controlled ovarian hyperstimulation: a comparison of basal and clomiphene citrate-stimulated follicle-stimulating hormone levels. Fertil. Steril., 57, 819–824.[ISI][Medline]

Tinkanen, H., Blauer, M., Laippala, P., Tuohimaa, P. and Kujansuu, E. (1999) Prognostic factors in controlled ovarian hyperstimulation. Fertil. Steril., 72, 932–936.[ISI][Medline]

Toner, J.P., Philput, C.B., Jones, G.S. and Muasher, S.J. (1991) Basal follicle-stimulating hormone level is a better predictor of in vitro fertilization performance than age. Fertil. Steril., 55, 784–791.[ISI][Medline]

Vale, W.W., Hunseuh, A., Rivier, C. and Yu, J. (1990) The inhibin/activin family of hormones and growth factors. In Sporn, M.A. and Roberts, A.B. (eds), Peptide Growth Factors and their Receptors: Handbook of Experimental Physiology, vol. 95. Springer-Verlag, Berlin, Germany, pp. 211–248.

Welt, C.K., McNicholl, D.J., Taylor, A.E. and Hall, J.E. (1999) Female reproductive aging is marked by decreased secretion of dimeric inhibin. J. Clin. Endocrinol. Metab., 84, 105–111.[Abstract/Free Full Text]

Submitted on January 17, 2002; resubmitted on March 21, 2002; accepted on May 16, 2002.