Assisted Reproduction: Clinical Practice

Tubal Factor Infertility

IVF was initially developed as a treatment for tubal factor infertility. Tubal occlusion is typically diagnosed with a hysterosalpingogram but may also be identified with laparoscopic chromopertubation or hysterosalpingo-contrast sonography. It should be noted that proximal tubal occlusion often can be artifactual due to tubal spasm, and the diagnosis should be confirmed with either repeat imaging or laparoscopic chromopertubation. For cases of true proximal occlusion, a fluoroscopic-guided tubal recanalization is an option. Tubal reanastomosis also can restore tubal patency and provide reasonable live birth rates, in particular among patients with prior surgical sterilization. The decision to proceed with tubal reconstruction versus IVF in these cases is complex and should factor in patient age, other causes of infertility, desired family size, and cost of treatment.

For patients with distal tubal occlusion, surgical repair and IVF are both possible therapeutic options, although no prospective trials have been reported comparing their relative efficacies. Clinical experience indicates that IVF provides higher delivery and lower ectopic rates compared to surgery. However, surgery is reasonable in women < 35 years of age with no other causes of infertility and mild tubal disease; pregnancy rates in other patient populations are poor. It is clear that the presence of communicating hydrosalpinges (defined as fluid-filled tubes on ultrasound, not merely occluded fallopian tubes) is detrimental to IVF outcomes. There are several meta-analyses of IVF outcomes in the setting of hydrosalpinges. A 2010 Cochrane review indicates that unilateral or bilateral removal of hydrosalpinges, or interruption of the hydrosalpinges, results in two- to fourfold higher delivery rates in IVF compared to no intervention. Initial concern about the possibility that interruption of collateral blood vessels to the ovary at the time of salpingectomy may reduce ovarian reserve has not been borne by larger studies and meta-analyses. A 2016 meta-analysis that compared IVF cycles immediately prior to salpingectomy for ectopic or hydrosalpinx to cycles following surgery found no differences in total gonadotropin dose, peak estradiol, number of oocytes obtained, or clinical pregnancy between the groups (18 studies, n = 1482).

Endometriosis

For women presenting with infertility and early-stage endometriosis, IVF has not been definitively shown to be superior to other available treatments, such as expectant management, human menopausal gonadotropin (hMG) with intrauterine insemination (IUI), or surgical treatment (see Chapter 30 ). However, several nonrandomized studies suggest that IVF treatment results in a higher pregnancy rate per cycle than conception attempts after surgical treatment, hMG with IUI, clomiphene treatment with IUI, or expectant management. For example, one retrospective study of 313 women with endometriosis and infertility evaluated cumulative pregnancy rates following gonadotropin IUI versus IVF. The pregnancy rate after one cycle of IVF was significantly higher than that of 6 cycles of gonadotropin IUI (47% vs. 41%; P < 0.05). After stratification by disease stage, the benefit of IVF was more pronounced, and women with stage IV endometriosis and age > 38 years were much more likely to conceive from IVF than from IUI treatment.

Patients often ask whether surgical treatment of early endometriosis prior to IVF improves the likelihood of pregnancy. There are no randomized trials to address this issue. However, a retrospective study evaluating the utility of diagnostic laparoscopy prior to IVF demonstrated that treatment of stage I or II endometriosis (n = 399) was associated with higher implantation and live birth rates per oocyte retrieval compared to diagnostic laparoscopy alone (n = 262) in patients with peritoneal endometriosis (implantation: 30.9% vs. 23.9%, P = 0.02; live birth: 27.7% vs. 20.6%, P = 0.004).

Women with advanced-stage endometriosis have lower ovarian reserve than women without endometriosis. A meta-analysis of 33 studies demonstrated that women with endometriomas had a twofold higher cycle cancellation rate and significantly fewer oocytes retrieved than women without endometriomas; however, the overall live birth rate was not different between the groups. Surgical resection of an endometrioma can have a further temporary detrimental effect on ovarian reserve, as measured by serum AMH pre- and postoperatively. Surgery can likewise impair ovarian responsiveness to gonadotropins. In an RCT of ovarian cystectomy for endometrioma followed by IVF versus immediate IVF, the surgery group required a longer duration of COS (14.0 vs. 10.8 days; P = 0.001), higher total gonadotropin dose (4575 IU FSH vs. 3675 IU FSH; P = 0.001) and had fewer mature oocytes retrieved (7.8 vs. 8.6; P = 0.03). There was no difference in fertilization, implantation, or pregnancy rates. In the most extreme cases, bilateral ovarian cystectomies for endometriomas have been associated with a 2.5% rate of ovarian failure. Accordingly, unless pathologic confirmation of a complex ovarian cyst is necessary, or the location of an endometrioma would prevent safe oocyte retrieval, observation of advanced endometriosis in favor of immediate IVF has become an increasingly acceptable approach. If an endometrioma is encountered during oocyte retrieval, it should not be purposefully aspirated due risk of abscess formation.

For patients with all stages of endometriosis who are planning to undergo IVF, a meta-analysis of 3 RCTs including 165 infertile women with endometriosis who were randomized to receive either 3-6 month pretreatment with depot GnRH agonist versus no treatment demonstrated that GnRH agonist treatment may significantly increase the odds of clinical pregnancy and live birth.

Male Factor

Male factor infertility is a broad category that ranges from minimally abnormal semen parameters to nonobstructive azoospermia. Because abnormal semen analysis values are only suggestive of male infertility and have low predictive power, follow-up analyses may be necessary to evaluate fertilization ability. ^, In general, men with severe semen abnormalities are best treated with ICSI (see Chapter 23 ). Severe oligoasthenospermia (less than 1.5 million motile sperm per ejaculate) and severely isolated teratospermia are associated with poor pregnancy rates in standard IVF. ^, Typically, ICSI is indicated for men with fewer than 10 million sperm/mL or less than 5 million/mL after processing. Prior to undergoing ICSI, men with less than 5 million sperm per mL in unwashed ejaculate should have a karyotype and Y chromosome microdeletion assessment because the incidence of karyotypic and genetic abnormalities is high in this group. In a study of 1935 men with severe male factor infertility (1214 with nonobstructive azoospermia and 721 with severe oligoasthenospermia), the incidence of karyotypic abnormalities was 16.4% and 5.8%, respectively. The incidence of Y chromosome microdeletions was 9.5% and 1.9%, respectively. While other studies have reported lower rates of abnormal karyotypes and questioned the value of routine screening, the preponderance of data suggests continued screening and patients with normal karyotypes are generally good candidates for IVF. ICSI in cases of severe male factor infertility results in fertilization and pregnancy rates comparable to those seen in standard IVF (see Chapter 32 ).

DNA damage in sperm has been shown to be associated with male infertility and decreased outcomes in couples undergoing IVF, although the data remain controversial due to variations in testing procedures and conflicting data. In general, testing for DNA damage may be useful in some cases of infertility, including couples with a history of recurrent miscarriage or poor IVF outcomes, but general guidelines recommend selective testing rather than routine screening of infertile men. A recent meta-analysis reports that evaluation of chromatin structural abnormalities, as measured by protamine abnormalities, is associated with male subfertility and closely related to sperm DNA damage. This line of sperm evaluation may be of utility in the future but has not been widely accepted presently. Lastly, sperm epigenetic assays may offer novel insight into poor IVF outcomes, although they are not yet validated for routine screening.

Idiopathic Infertility

For 10 to 17% of infertile couples, a thorough evaluation reveals no identifiable cause of infertility. Data reported to the national summary CDC data for 2019, indicate that 10.8% of IVF/ICSI cycles initiated were for a primary infertility diagnosis of “unexplained factor” infertility ( Fig. 35.1 ).

Many couples with idiopathic infertility become pregnant after a stepwise treatment approach (see Chapter 30 ), which may include superovulation with clomiphene IUI followed by gonadotropin IUI and then IVF. Two RCTs have been performed to determine the most effective treatment approach for achieving live birth among patients initiating care for unexplained infertility. In the Fast Track and Standard Treatment Trial (FASTT), 503 women ages 21 to 39 years with at least 12 months of unexplained infertility were randomized to one of two treatment groups: a conventional approach with three cycles of clomiphene IUI, followed by three cycles of gonadotropin IUI, then up to six cycles of IVF; or an accelerated approach that omitted the gonadotropin IUI cycles. Delivery rates per cycle of treatment were 7.6% for clomiphene IUI, 9.8% for gonadotropin IUI, and 30.7% for IVF. Couples allocated to the accelerated arm were pregnant on average 3 months earlier than those allocated to the conventional arm (8 vs. 11 months), and the cost per delivery was $9,800 less for the accelerated arm. The Forty and Over Treatment Trial (FORT-T) randomized 154 women ages 38 to 42 years with at least six months of unexplained infertility to either two cycles of clomiphene IUI or two cycles of gonadotropin IUI, then up to six cycles of IVF, or directly to IVF. The cumulative clinical pregnancy rates after the first two cycles were 21.6%, 17.3%, and 49.0%, respectively. Importantly, 84.2% of all live births in the study were achieved with IVF, and significantly fewer treatment cycles were required in the immediate IVF group. Accordingly, among patients < 38 years with unexplained infertility, a fast track to IVF may be the most effective approach in terms of cost and time spent in treatment; among patients ≥ 38 years of age, proceeding directly to IVF is reasonable based on the available evidence.

Polycystic Ovary Syndrome and Anovulation

Traditionally, infertile women with polycystic ovary syndrome (PCOS) in whom both clomiphene and gonadotropin ovulation induction failed had few remaining treatment options except surgical procedures like ovarian diathermy to reduce thecal androgen production. However, evidence has accumulated that IVF is often effective for such patients. A meta-analysis of 9 studies comparing IVF outcomes in 458 PCOS patients, as defined by the Rotterdam criteria, to 694 matched non-PCOS patients found that PCOS patients required on average 1.2 days longer for stimulation, and had higher cycle cancellation rates, higher oocyte yields, lower fertilization rates, but equivalent clinical pregnancy rates per embryo transfer. As the incidence of oocyte immaturity is high among PCOS patients, the similar clinical pregnancy rates reported in this study are reassuring.

PCOS patients are at high risk of ovarian hyperstimulation syndrome (OHSS), in particular those with an AMH > 3.5 ng/mL or an antral follicle count > 16. This risk may be mitigated by the use of GnRH antagonists rather than agonists for pituitary suppression, coupled with a GnRH agonist trigger instead of hCG to induce final oocyte maturation. There is conflicting evidence about the utility of metformin in PCOS patients during IVF in the prevention of OHSS. A placebo-controlled RCT of 120 PCOS patients treated with metformin 500 mg three times per day during IVF treatment with a long GnRH agonist protocol until menses or a positive pregnancy test revealed that the relative risk of OHSS was 0.28 (95% CI 0.11–0.67). The metformin arm also used somewhat more gonadotropins (1350 [range, 950–1800] vs. 1275 [range 900–1750], P = 0.018), had fewer nonperiovulatory follicles on the day of hCG administration (4.3 [range, 0–6] vs. 5.5 [range, 2–9], P = 0.034) and lower estradiol levels at hCG (1951 pg/mL [range, 342–4021], vs. 2346 [range, 709–4123], P = 0.29). Implantation rates (41 vs. 31%) and live birth rates (29 vs. 27%) per cycle were not different. ^, In contrast, another RCT of metformin prescribed to PCOS patients during an antagonist cycle, instead of an agonist cycle, showed no reduction in the incidence of moderate to severe OHSS, and surprisingly a lower clinical pregnancy (28.6 vs. 48.7%; P = 0.02) and live birth rate (27.5 vs. 51.6%; P = 0.02) per cycle. Other interventions that may reduce the OHSS risk include coasting, glucocorticoids, dopamine agonists, colloid infusion, GnRH-agonist-only triggers, and elective cryopreservation of all embryos with deferred transfer are discussed below.

For women with hypothalamic amenorrhea, as with PCOS, treatment with IVF avoids a high risk of multifollicular development with gonadotropins, which is known to lead to a high risk of multiple gestation (see Chapter 30 ).

Uterine Factor

The uterus may be considered abnormal and a contributor to infertility due to many factors, including acquired defects such as fibroids, adenomyosis, polyps or intrauterine adhesions, and also due to congenital anomalies.

Cervical Stenosis

Cervical stenosis can impair effective embryo transfer and thus lower pregnancy rates with IVF. Placing a transcervical Malecot catheter after hysteroscopic evaluation in preparation for IVF appears to improve the ease of embryo transfer in women with cervical -stenosis. Other methods include cervical dilation at the initial visit, use of laminaria, and resection of cervical ridges.

Congenital Defects

Müllerian anomalies appear to be associated with a reduced pregnancy rate in IVF. Only retrospective cohort and case-control studies are available to guide patient counseling, though. In a study of 37 women with müllerian anomalies undergoing their first IVF cycle, including those with in utero diethylstilbestrol exposure, septate uterus, bicornuate uterus, or uterine didelphys, the live birth rate per initiated cycle was 8%, compared with 25% in a control group without müllerian anomalies ( P = 0.02). In a case-control study that matched women with and without a septate uterus undergoing two consecutive embryo transfers in a 1:2 ratio, the presence of an unresected septum was associated with a significantly decreased live birth rate (3/113, 2.7% vs. 49/226, 21.7%; P = 0.001). Following hysteroscopic septoplasty, the difference in live birth was no longer statistically significant (43/275, 15.6% vs. 115/550, 20.9%).

Decreased Ovarian Reserve

Decreased ovarian reserve is increasingly acknowledged as a major infertility factor and is likely second only to age as a predictor of IVF delivery rates. As a woman ages, the quantity and quality of her oocytes decrease, and, as shown in Fig. 35.2 , the proportion of IVF pregnancies that end in miscarriage increases due to increases in oocyte aneuploidy. However, notably, the incidence of miscarriage in women >44 years is similar to that of women 42 years old, presumably due to selection of women with more favorable ovarian reserve in this upper age group. In addition to the chronologic age of the female partner, the biologic age of the ovary, which is an estimate of the remaining resting follicular pool as determined by ovarian reserve tests, such as cycle day 3 follicle-stimulating hormone (FSH), antimüllerian hormone (AMH), inhibin, and antral follicle count (AFC), is also a strong predictor of IVF pregnancy rates. These markers, along with patient age, have been used to standardize the definition of expected poor-responders according to the Bologna criteria, in which a patient may be classified as such if at least two of the following three criteria are present: (1) age > 40 years; (2) a history of prior poor response to gonadotropins using a conventional stimulation protocol (≤ 3 oocytes); or (3) AMH below 0.5 to 1.1 ng/mL or AFC less than 5 to 7 follicles.

Evaluation of Ovarian Reserve

Cycle Day 3 FSH

Basal FSH values, when measured in the early follicular phase and interpreted in the context of a paired estradiol value, correlate with response to gonadotropins and the likelihood of pregnancy following IVF. FSH values, particularly when above a threshold of 10 mIU/L, are inversely correlated with peak estradiol and the number of oocytes retrieved. This threshold has a high specificity (> 80%) for predicting poor response but a low sensitivity (10%–30%). A large study of 18,019 IVF cycles (mean patient age 36.2 ± 4.8 years) investigated the relationship between cycle day 3 FSH concentration and IVF delivery rates. FSH levels measured by several types of FSH assays were included, as this reflects actual clinical practice. A threshold between normal and abnormal FSH levels was then assessed. The study showed that no live births occurred in this older population with basal FSH levels of > 18.0 mIU/ml and that between 1 and 7 mIU/ml live birth rates were relatively constant but underwent a decline between 8 and 12 mIU/ml, which was more precipitous beyond 13 mIU/ml ( Fig. 35.3 ). Similar trends were observed for each age group. When the interaction of age and the results of a clomiphene challenge test were examined, in women with a normal clomiphene citrate challenge test response (suggesting an adequate follicular pool), the age of the female partner remained an important prognostic variable. It should be noted that the method used to establish the threshold to separate “normal” from “abnormal” FSH levels greatly affects its predictive ability.

AMH

AMH is a glycoprotein growth factor synthesized by granulosa cells in preantral and antral follicles. Low AMH values correlate with a decreased response to gonadotropins. Several studies have demonstrated that AMH is inversely correlated with age and, as such, is a useful marker of ovarian reserve. An age-based nomogram of AMH is shown in Fig. 35.4 . Seifer et al were the first to demonstrate that AMH is significantly reduced in women who responded poorly to ovarian stimulation in IVF cycles. A meta-analysis of 13 studies that evaluated the clinical utility of AMH in predicting IVF response summarized the specificity of a low value as 64% to 100%, with a sensitivity ranging from 40% to 91% depending upon the threshold used. Importantly, AMH has not been found to be an independent predictor of IVF pregnancy. A multivariate analysis of over 5000 autologous IVF cycles with an ultralow AMH value (< 0.17 ng/mL) indicated that while cycle cancellation occurred in 54% of all cases and there was a significantly higher rate of having either no embryos for either transfer or cryopreservation when compared to age-matched controls with normal AMH values, the live birth rate was still 9.5% per cycle start. Accordingly, refusal of treatment based solely on a low AMH value, regardless of the cut-off used, is not encouraged.

AMH also has the advantage of minimal cycle-to-cycle variation and its levels do not change significantly across the menstrual cycle. In a multivariate analysis of 1643 women ages 23 to 35, current users of hormonal contraceptives had 25.2% lower mean AMH levels than nonusers of hormonal contraceptives (95% CI −35.3%, −13.6%). This effect appeared to be reversible, as there was no significant difference in AMH levels between former users and nonusers of hormonal contraceptives (−4.4%; 95% CI −16.3%, 9.0%).

Inhibin

Inhibin B, a glycoprotein hormone secreted by the granulosa cells, has also been studied as a marker of ovarian reserve. Inhibin B directly inhibits the pituitary secretion of FSH in a manner similar to that of estradiol and thus was thought to be a marker of ovarian health. However, the utility of inhibin B as a marker of ovarian reserve is limited by the lack of a uniform commercial assay and poor performance characteristics of the test.

AFC

The AFC (the total number of follicles between 2 mm and 9 mm visualized on transvaginal ultrasound) appears to be a better predictor of ovarian reserve than FSH and performs similarly to a low AMH value in predicting poor response. Women with fewer than 7 total antral follicles have DOR and generally have poorer outcomes in IVF. Also similar to AMH, the AFC has very limited accuracy in predicting IVF pregnancy—rather, it is helpful in choosing stimulation regimens and gonadotropin dosing, along with counseling about the risk of cycle cancellation or overresponse.

Genetic Abnormalities

Couples with or without infertility who are carriers of monogenic (single gene) defects, chromosomal structural rearrangements, or who are at high risk for aneuploidy are candidates for preimplantation genetic testing (PGT), the purpose of which is to reduce the likelihood of transferring an affected embryo(s). The testing is referred to as PGT-M for monogenic defects, PGT-SR in cases of structural rearrangements, or PGT-A for aneuploidy testing. Typically, several embryos are required for such testing because: (1) the preferred stage for biopsy is the blastocyst (i.e., for trophectoderm biopsy) and not all embryos form blastocysts in vitro ; (2) depending on the genetic abnormality being tested, at least 25% of those biopsiable are likely to be unsuitable for transfer (e.g., in cases of recessive conditions); and (3) in cases of concurrent comprehensive chromosomal screening at the same time as testing for single gene mutations, ^{, 84} there may be a further reduction in the number of suitable embryos available for transfer.

Notably, PGT with trophectoderm biopsy requires a freeze-all cycle to allow for the genetic testing to be completed before transfer. Patient counseling about these considerations, along with other limitations of PGT is critical, including the possibility of having no embryos available for biopsy, no normal embryos available for transfer, nondiagnostic results, the possibility of a false-positive or false-negative result, mosaic embryos, as well as having embryos with microduplications or microdeletions of unknown significance. PGT is discussed further later in this chapter and in Chapter 36 .

Natural Cycle IVF

Natural cycle IVF is possible through careful monitoring of the menstrual cycle with serum hormones and transvaginal sonography, in order to identify the time when the dominant follicle can be aspirated to yield a fertilizable oocyte. Although conceptually appealing, and the way in which the field of clinical ART was indeed born, natural cycle IVF is associated with low pregnancy rates. In one study of 74 such cycles, oocytes were only harvested in approximately 50% of cycles, and the pregnancy rate per cycle initiated was 3%. In another study of 114 natural IVF cycles, the pregnancy rate per cycle initiated was 4%. IVF is a resource-intensive treatment, and pregnancy rates in the range of 3% to 4% per IVF cycle initiated are not cost-effective.

One reason offered by advocates of natural cycle IVF is that oocytes derived from stimulated cycles may have an increased rate of aneuploidy; this concern is not supported by evidence, however. A recent prospective study demonstrated that there was no difference in the aneuploidy rate of blastocysts derived from natural (n = 147; 44%) versus conventional stimulation cycles (n = 6664; 42%; P = 0.81). The delivery rate per euploid transfer was equivalent between natural and stimulated cycles (58.7% vs. 59.0%), but natural cycles were more likely to have no oocytes retrieved, no blastocysts to biopsy or cryopreserve, and no euploid embryos to transfer.

Mild Ovarian Stimulation

“Mild stimulation” regimens, although heterogeneously defined in the literature, have been gaining in popularity. Such regimens may include the use of clomiphene or aromatase inhibitors with 75 to 150 IU of gonadotropins, but some publications report the total gonadotropin doses to be actually quite high. There are several RCTs to indicate that among both expected good and poor responders, a mild approach with a GnRH-antagonist and low-dose gonadotropins may result in pregnancy rates comparable to those achieved using a long GnRH-agonist with conventional COS. These studies are limited by the comparison of two different regimens for pituitary suppression (agonist vs. antagonist) and the selection of a comparator group that would not typically be recommended for a poor responder (long agonist). Furthermore, the cumulative pregnancy rates of such an approach remain to be determined. In Europe, such treatment has been more widely adopted, perhaps in part because many countries have legislation restricting the number of embryos that may be cultured, as well as more restrictive age limits for IVF.

Standard Controlled Ovarian Stimulation

The approach most commonly used in the United States is based on data showing that higher numbers of oocytes have been shown to optimize pregnancy rates at all ages. Consequently, success is critically dependent on generating an adequate number of mature follicles that contain developmentally competent oocytes, while avoiding OHSS. Large retrospective cohort studies suggest that obtaining enough embryos to allow for embryo selection is important in order to maximize pregnancy rates. One study of 7422 women treated with the long GnRH-agonist protocol found that pregnancy rates per initiated cycle were highest when 13 oocytes were obtained (28%). Another study of 400,135 IVF cycles performed between 1991 and 2008 also found that the pregnancy rate per cycle correlated with the number of oocytes retrieved. The median number of oocytes retrieved was 9, with a live birth rate per initiated cycle of 21%. Live birth rates correlated with the number of oocytes retrieved across all age groups, and were maximal when 15 oocytes were obtained, plateaued between 15 and 20 oocytes, and were lower if over 40 oocytes were retrieved. Therefore, the predominant approach to ovarian stimulation for IVF in the United States is to aim for the development of multiple follicles in order to allow for embryo selection, particularly in women at advanced ages (i.e., > 38 years of age) when aneuploidy rates increase and implantation rates concomitantly decrease.

Medications used for ovarian stimulation include clomiphene, clomiphene-hMG; clomiphene-rhFSH (-recombinant human FSH); hMG alone; immunopurified (highly purified) urinary human FSH (hpFSH) alone; rhFSH alone, and various combinations of the above. Compared to clomiphene alone, the combination of clomiphene plus low dose human gonadotropins (FSH or hMG) increases the number of follicles stimulated, but the number of oocytes retrieved, and the pregnancy rates are lower than expected with standard stimulation in normal responders. Though such regimens do allow for lower-cost stimulations, the live birth rate per stimulation is low. Therefore, in terms of the expected live birth rate per initiated stimulation and the cumulative live birth rate, these regimens are likely inferior to standard dosing of gonadotropins alone and may not ultimately be cost effective.

Below we focus on COS protocols as used for IVF in the US. In addition, we consider decision making in protocol selection.

Normal and High Responder Regimens

GnRH-Agonist Downregulation Protocol

In ovarian stimulation for IVF, the main purpose of a GnRH-agonist analog or antagonist is to prevent a premature LH surge (triggered by positive feedback from high estradiol) while the follicles are still immature. Accordingly, pituitary suppression reduces premature luteinization of granulosa cells and premature ovulation.

GnRH-agonist analogs differ from the native decapeptide GnRH in amino acid positions 6 and 10. They are resistant to degradation, so they have long half-lives and prolonged receptor occupancy. The initial administration of a GnRH-agonist analog is associated with an increase in LH and FSH secretion (agonist phase). Long-term administration causes downregulation and partial desensitization of the pituitary GnRH receptor, resulting in the suppression of pituitary gonadotropin secretion. In the standard downregulation protocol, the GnRH-agonist (0.5 to 1 mg daily) is begun in the midluteal phase of the prior menstrual cycle, and ovarian stimulation begins with or after the onset of the subsequent menstrual period, at which time the GnRH-agonist dose is decreased by half ( Fig. 35.11 ; Table 35.2 ). Due to the suppressive nature of the pituitary gland of prolonged GnRH-agonist exposure, hCG is required for ovulatory triggering, which has implications for expected high-responders (see below).

Table 35.2

Summary Table of IVF Stimulation Protocols for Expected High, Normal, and Poor Responders

Normal or High Responders
	Indications	Regimen	Trigger Options	Special Considerations
GnRH-agonist long protocol	Endometriosis, adenomyosis, poor embryo development on GnRH-antagonist regimen	- Start GnRH-agonist at luteal check or overlap with 2–3 weeks of OCPs - 0.5 mg decreased to 0.25 mg with menses	- hCG only	- Can use diluted GnRH-agonist (0.2–0.1 mg; or 0.1–0.05 mg) - Higher risk of OHSS
GnRH-antagonist	PCOS, expected high responders (e.g., oocyte donors), fertility preservation, random start	- 1–3 weeks OCPs vs. straight-start - GnRH-antagonist when E 2 > 300 pg/mL or lead follicle > 13–14 mm	- hCG only - Dual hCG/GnRH agonist - GnRH-agonist only	- Often first-line protocol - Patient friendly (fewer injections, less gonadotropin requirement, less monitoring visits, ease of scheduling)
Poor Responders
Luteal estradiol priming	Prior dyssynchronous follicular cohort or poor response to another cycle type	- Following luteal check, start E2 until menses - No OCPs - Standard GnRH-antagonist start	- hCG only - Dual hCG/GnRH agonist - GnRH-agonist only	- May use transdermal patch or micronized oral estradiol
GnRH-agonist microflare	Considered alternate to priming protocol for low responders	- Minimize OCP lead-in (straight start vs. maximum 7 days to avoid oversuppressed) - Day 2 follicular start of GnRH-agonist (0.05 mg) Q12H	- hCG only	- May rescue corpus luteum from prior cycle, leading to premature progesterone elevation - Brief OCP lead-in can prevent corpus luteum rescue
DuoStim	Low responder, emergency fertility preservation	- Restart gonadotropins 3–5 days post retrieval to recruit next wave of antral follicles	- hCG only - Dual hCG/GnRH agonist - GnRH-agonist only	- Allows accumulation of more oocytes in same amount of time

Compared to no suppression, the addition of a GnRH-agonist analog to regimens of ovarian stimulation for IVF-ET is associated with a lower cancellation rate, and an increase in the number of oocytes -retrieved, the number of embryos available for transfer, and the clinical pregnancy rate. ^, For example, one study demonstrated that treatment with a GnRH-agonist (buserelin) plus hMG resulted in more oocytes retrieved (9.3 vs. 6.2), more embryos (4.3 vs. 2.8), and a higher clinical pregnancy rate (20% vs. 14%) than did stimulation with clomiphene plus hMG. In another study, a comparison of a stimulation regimen using the same medications also demonstrated that buserelin-hMG stimulation resulted in a higher pregnancy rate than that observed with clomiphene-hMG (36% vs. 18%). The type of GnRH-agonist analog used does not appear to be crucial to obtaining improved outcomes. Studies with D-Trp6 GnRH-agonist analog also demonstrate higher pregnancy rates (21% vs. 12%) compared with ovarian stimulation regimens that do not use GnRH-agonists for IVF-ET.

It is important to note that women with normal ovarian reserve typically will produce optimal numbers of oocytes from downregulation regimens but may be at an increased risk of OHSS compared to a GnRH-antagonist regimen (see below). In contrast, women with DOR may not respond even to high-dose gonadotropin treatment after downregulation. In some cases, employing lower doses of GnRH-agonists will allow downregulation without excessive suppression of response. ^, An RCT of a half-dose of triptorelin (1.87 mg) adequately suppressed the pituitary but required a lower dose of FSH (42 ± 2 vs. 59 ± 3 ampules) and more mature oocytes (10.1 ± 0.54 vs. 7.4 ± 0.6), zygotes (8.2 ± 0.4 vs. 6.3 ± 0.4) and embryos (7.8 ± 0.36 vs. 5.9 ± 0.37) were obtained than when the standard 3.75 mg dose was given. There were no significant differences in pregnancy (half-dose: 38.8% vs. full-dose: 25.3%), implantation (22.6% vs. 13.8%), or miscarriage (6.1% vs. 5.0%) rates, though, a trend for improved outcomes with the lower dose agonist was observed. Furthermore, the cumulative pregnancy rate was significantly higher in the lower dose agonist group (56.8% vs. 35.4%). Variations of the full-dose (1 to 0.5 mg) or low-dose (0.5 to 0.25 mg/d) long-luteal protocol include a very low dose (0.2 to 0.1 mg/d), an ultralow dose (0.1 to 0.05 mg/d), and a pseudoluteal start overlapping with OCPs.

GnRH-Antagonist Protocol

A theoretical problem with the GnRH-agonist analogs is that LH secretion is stimulated at the initiation of treatment, which is not consistent with the physiology of the normal early menstrual cycle. GnRH-antagonists offer the possibility of acutely suppressing LH secretion without an initial increase in LH release. ^, Thus, pituitary LH secretion can be controlled within the stimulation cycle itself; such control is not possible with the GnRH-agonists, which must be begun during the previous menstrual cycle to achieve full downregulation. GnRH-antagonists have extensive amino acid substitutions compared to native GnRH at positions 1 to 3, 6, occasionally 8, and 10. They act as competitive inhibitors of the GnRH receptor, such that they can off-compete endogenous GnRH, leading to an acute decrease in gonadotropin secretion within 24 hours. GnRH-antagonists are typically administered as a small daily dose (cetrorelix or ganirelix, 0.25 mg daily by subcutaneous injection), usually starting on cycle day 6 to 8 or when the lead follicle reaches 14 mm in diameter or as a single large dose (cetrorelix, 3 mg subcutaneously, which has a four-day duration of action) on approximately cycle day 8 ( Fig. 35.12 ; Table 35.2 ). Both protocols block a spontaneous LH surge.

The impact of a GnRH-antagonist on ovarian stimulation for IVF is dependent on the dose of GnRH antagonist administered. At small doses, the suppression of LH is minimal. With large doses, near-complete suppression of LH is achieved. In one study, the impact of six doses of the GnRH-antagonist ganirelix on LH secretion and IVF outcomes was studied. A fixed daily dose of recombinant FSH was administered. Ganirelix produced a dose-dependent suppression not only of LH but also of serum androstenedione and estradiol, with the maximal pregnancy rate per cycle with a dose of ganirelix 0.25 mg.

The use of oral contraceptives prior to GnRH-antagonist cycles is common in order to have some control over the start of cycles. Initial studies that lead to FDA approval used oral contraceptives for approximately 3 weeks prior to stimulation. A three-arm RCT comparing OCP pretreatment in GnRH-antagonist (n = 110) versus agonist (n = 111) versus GnRH-antagonist without OCP treatment (n = 111) showed that the OCP-scheduled antagonist regimen appeared more similar to the agonist regimen rather than the no-OCP GnRH antagonist regimen. Suppression following OCP use was more profound at the start of stimulation ( P ≤ 0.001), as manifested by slower follicular growth ( P ≤ 0.001), longer stimulation (11.7 and 10.3 vs. 9.4 days, respectively; P ≤ 0.001), and more rFSH utilized (2667 and 2222 IU vs. 1966 IU; P ≤ 0.001). In the three groups, both the number of oocytes (13.1, 12.9, and 11.5, respectively) and the number of good-quality embryos (5.1, 5.7, and 5.0, respectively) were similar. One meta-analysis evaluated 4 RCTs in 847 patients and found no difference in ongoing pregnancy rates, though the duration of stimulation and gonadotropin requirements were higher after OCP pretreatment. In clinical practice, 7 to 21 days of OCPs are often prescribed to patients prior to a GnRH-antagonist cycle. Not all patients have a withdrawal bleed after oral contraceptives, so a baseline ultrasound is performed on day 2 of the menstrual period following pill cessation, or 4 days after the last pill, as the vast majority of women will have had a withdrawal bleed by that point.

One important variation is the random start GnRH-antagonist cycle, in which gonadotropins are initiated on any day of the menstrual cycle with or without a simultaneous GnRH-antagonist to promote luteolysis, as needed. ^, If the GnRH-antagonist is not started at the same time as the gonadotropins, it is added at an appropriate time based on serum estradiol and lead follicle diameter to prevent the LH surge. This protocol is typically only used for fertility preservation cases in which there is a narrow time window prior to the planned gonadotoxic treatment. Preliminary data comparing the random (n = 35) versus conventional (n = 93) GnRH-antagonist starts to demonstrate an equivalent yield of total and mature oocytes and similar fertilization rates. Little is known about subsequent embryo development or pregnancy rates following a random start.

Another variation is luteal priming with oral or transdermal estradiol in an effort to promote follicular synchronization and endogenous FSH flare in the early follicular phase, as described below in the section on poor responders.

GnRH-antagonists have several advantages compared to GnRH-agonist protocols in terms of the number of days requiring injectable medication, total gonadotropin dose, risk of OHSS, trigger options for final oocyte maturation, and the effect on endometrial receptivity, as outlined below. In contemporary IVF practice, GnRH-antagonist protocols are now considered the protocol of choice for many patients undergoing their first IVF cycles with an expected normal or high response.

GnRH-Agonist Versus GnRH-Antagonist Protocols

Most studies of IVF have demonstrated that both GnRH-agonists in a downregulation protocol and GnRH-antagonists are associated with similar rates of cycle cancellation due to a premature LH surge. A 2016 Cochrane review of 73 RCTs (n = 12,212) comparing the long GnRH-agonist to GnRH-antagonist protocol in women with normal ovarian reserve found that with GnRH-antagonists, the cancellation rate due to overresponse was lower (OR 0.47, 95% CI 0.32–0.69; 19 RCTs, n = 4256), but the cancellation rate due to poor response was higher (OR 1.32, 95% CI 1.06–1.65; 25 RCTs, n = 5230). Importantly, there was no evidence of a statistically significant difference in live birth rates (OR 1.02, 95% CI 0.85–1.23; 12 RCTs, n = 2303) or miscarriage (OR 1.04, 95% CI 0.82–1.30; 33 RCTs, n = 7022).

GnRH-antagonists are often regarded as more patient-friendly, as well, due to the fewer days of analog administration (5.7 ± 2.3 vs. 25.6 ± 7.6 d; P < 0.001), shorter stimulation (10.6 ± 2.3 vs. 11.4 ± 1.8 d; P < 0.01), and less total gonadotropin usage (23.6 ± 8.5 vs. 25.6 ± 7.6 ampules hMG; P < 0.01).

Furthermore, in a meta-analysis of 36 RCTs (n = 7944), there was nearly a 40% reduction in the incidence of OHSS in the GnRH-antagonist group (OR 0.61, 95% CI 0.51–0.72). The trigger options for final oocyte maturation are also more flexible with GnRH-antagonists, including hCG only, GnRH-agonist only, and dual hCG/GnRH-agonist. As described below, these GnRH-agonist triggering options provide clinicians with the opportunity to further minimize the risk of OHSS in high responders who are planning to undergo a freeze-all cycle or a fresh transfer.

Finally, endometrial receptivity may be more physiologic in GnRH-antagonist cycles. An analysis of paired endometrial biopsies from the same patients undergoing a natural cycle versus a GnRH-agonist or GnRH-antagonist normalized to the LH surge indicated that the microarray signature following GnRH-antagonist exposure more closely recapitulates that of the unstimulated cycle. ^, For example, in GnRH-agonist cycles, only 15% of genes tested showed a similar pattern of differential expression as compared to an unstimulated cycle; specifically, genes involved in cell cycle expression, such as cyclins, CDC, CDK, and members of the E2F family of transcription factors were downregulated, while genes normally upregulated in natural cycles, including ones involved in TGF-β signaling , the complement pathway, coagulation cascade, and leukocyte migration failed to be upregulated in GnRH-agonist cycles. In contrast, the expression of 43% of these genes was shared in common between the GnRH-antagonist and unstimulated cycle.