Seventy years of progestagen treatments for management of the sheep oestrous cycle: where we are and where we should go.

Management of the ovine oestrous cycle is mainly based on the use of exogenous hormones to mimic or enhance (progesterone and its analogues) or manipulate (prostaglandin F2α and its analogues) the activity of the corpus luteum, combined with the application of other hormones mimicking the pituitary secretion of gonadotrophins (e.g. equine chorionic gonadotrophin). These protocols have been applied without major change for decades but, now, there are two reasons to reconsider them: (1) our greatly improved knowledge of the dynamics of ovarian physiology, following the application of transrectal ultrasonography, indicates that modification of the protocols may improve fertility yields and (2) increasing concerns about animal health and welfare, food safety and the environmental impact of the treatments, as evidenced by public opinion and therefore market forces. Here, we offer an overview of these issues, introduce an updated protocol and suggest ways for future improvements to the protocols.

Forty years of IVF.

This monograph, written by the pioneers of IVF and reproductive medicine, celebrates the history, achievements, and medical advancements made over the last 40 years in this rapidly growing field.

Development of in vitro fertilization in the United States: a conversation between Zev Rosenwaks and Jairo E. Garcia.

In commemoration of 40 years of in vitro fertilization (IVF), herein we describe the early evolution of the first IVF program at the Eastern Virginia Medical School in Norfolk, Virginia. The birth of the first American IVF baby was the result of the work of many investigators, both in experimental animal models and in humans, heavily relying on the experience of Robert Edwards and Patrick Steptoe in Great Britain. Although their first IVF baby was the result of the retrieval of a single oocyte in the natural cycle, duplicating their methods was not successful in Norfolk. It turns out that the achievement of the first pregnancy in the United States was associated with introducing ovarian stimulation with gonadotropins, establishing the appropriate timing for egg retrieval after hCG administration, retrieving multiple mature oocytes, determining the ideal time for in vitro insemination, and optimizing embryo culture media.

Ovarian hyperstimulation: past, present, and future.

The good physician treats the disease; the great physician treats the patient who has the disease. -William Osler.

Ovarian stimulation, insemination, and contraception.

We have come a long way in achieving, and preventing, pregnancy since 1966.

Historical perspectives and recent research on superovulation in cattle.

Superovulation protocols have evolved greatly over the past 40 to 50 years. The development of commercial pituitary extracts and prostaglandins in the 1970s, and partially purified pituitary extracts and progesterone-releasing devices in the 1980s and 1990s have provided for the development of many of the protocols that we use today. Furthermore, the knowledge of follicular wave dynamics through the use of real-time ultrasonography and the development of the means by which follicular wave emergence can be controlled have provided new practical approaches. Although some embryo transfer practitioners still initiate superstimulatory treatments during mid-cycle in donor cows, the elective control of follicular wave emergence and ovulation has had a great effect on the application of on-farm embryo transfer, especially when large groups of donors need to be superstimulated at the same time. The most common treatment for the synchronization of follicular wave emergence for many years has been estradiol and progestins. In countries where estradiol cannot be used, practitioners have turned to alternative treatments for the synchronization of follicle wave emergence, such as mechanical follicle ablation or the administration of GnRH to induce ovulation. An approach that has shown promise is to initiate FSH treatments at the time of the emergence of the new follicular wave after GnRH-induced ovulation of an induced persistent follicle. Alternatively, it has been suggested recently that it might be possible to ignore follicular wave status, and by extending the treatment protocol, induce small antral follicles to grow and superovulate. Recently, the mixing of FSH with sustained release polymers or the development of long-acting recombinant FSH products have permitted superstimulation with a single or alternatively, two gonadotropin treatments 48 hours apart, reducing the need for animal handling during superstimulation. Although the number of transferable embryos per donor cow superstimulated has not increased, the protocols that are used today have increased the numbers of transferable embryos recovered per unit time and have facilitated the application of on-farm embryo transfer programs. They are practical, easy to administer by farm personnel, and more importantly, they eliminate the need for detecting estrus.

Forty years of embryo transfer in cattle: a review focusing on the journal Theriogenology, the growth of the industry in North America, and personal reminisces.

After the first successful transfer of mammalian embryos in 1890, it was approximately 60 years before significant progress was reported in the basic technology of embryo transfer (ET) in cattle. Starting in the early 1970s, technology had progressed sufficiently to support the founding of commercial ET programs in several countries. Today, well-established and reliable techniques involving superovulation, embryo recovery and transfer, cryopreservation, and IVF are utilized worldwide in hundreds, if not thousands, of commercial businesses located in many countries. The mean number of embryos produced via superovulation has changed little in 40 years, but there have been improvements in synchrony and hormonal protocols. Cryopreservation of in vivo-derived embryos is a reliable procedure, but improvements are needed for biopsied and in vitro-derived embryos. High pregnancy rates are achieved when good quality embryos are transferred into suitable recipients and low pregnancy rates are often owing to problems in recipient management and not technology per se. In the future, unanticipated disease outbreaks and the ever-changing economics of cattle and milk prices will continue to influence the ET industry. The issue of abnormal pregnancies involving in vitro embryos has not been satisfactorily resolved and the involvement of abnormal epigenetics associate with this technology merits continued research. Last, genomic testing of bovine embryos is likely to be available in the foreseeable future. This may markedly decrease the number of embryos that are actually transferred and stimulate the evolution of more sophisticated ET businesses.

IVF endocrinology: the Edwards era.

Through pioneering human IVF as a global infertility treatment, Robert Edwards and his clinical partner Patrick Steptoe launched the field of IVF endocrinology. Following repeated failures with oocytes collected in human menopausal gonadotrophin (HMG) primed cycles timed to injection of human chorionic gonadotrophin (HCG), the first successful IVF pregnancy came from a spontaneous menstrual cycle. Intensive endocrine monitoring was used to track pre-ovulatory follicular development and collect a single ripe egg timed to the natural LH surge. Despite this groundbreaking achievement, ovulation induction was clearly required to make IVF treatment clinically robust and reliable. Ovarian stimulation with clomiphene citrate was used to achieve the first maternity from a superovulated human IVF cycle in 1980. HMG/HCG regimens were then successfully introduced-including substitution of 'pure' follicle-stimulating hormone as the principal ovarian stimulant. The application and success of IVF treatment were dramatically enhanced by the introduction of gonadotrophin-releasing hormone analogues that enabled elective control of endogenous gonadotrophin release during ovarian stimulation. Programmed gonadotrophin regimes yielding double-digit oocyte numbers became normal: 'more is better' was the ethos. Bob Edwards expressed increasing concern over the cost, complexity and potential long-term health risks of such high-order ovarian stimulation. In later life he repeatedly called for a return to minimalist approaches based on the natural menstrual cycle to improve oocyte quality over quantity. This article reviews the application of ovulation induction to human IVF and celebrates Edwards' abiding impact on the field, which firmly grounds him in the reproductive endocrinology pantheon.

A historical perspective of aromatase inhibitors for ovulation induction.

The concept of using aromatase inhibitors in place of clomiphene citrate (CC) for ovulation induction was introduced >10 years ago; a brief history of its development is presented. Its worldwide usage for ovulation induction, including as an adjunct for intrauterine insemination and in vitro fertilization has occurred despite the absence of definitive data of superiority to CC. The results of two ongoing potentially definitive multicenter trials of efficacy and safety of letrozole compared with CC are eagerly awaited.

History and challenges surrounding ovarian stimulation in the treatment of infertility.

OBJECTIVE: To examine the history of superovulation for ovulation induction, its contributions to reproductive medicine, and its impact on multiple births. DESIGN: A search of the relevant literature using PubMed and other online tools. RESULT(S): Infertility has been a condition known and studied for thousands of years. However, it was not until this past century that effective treatments were developed. With the advancement of our knowledge of the hypothalamic-pituitary axis, therapies utilizing gonadotropins were developed to stimulate ovulation. Not only could we now treat anovulatory infertility but also induce superovulation for IVF. With these successes came consequences, including increased multiple pregnancies. Several countries recognized the high costs associated with multiple births and implemented regulations on the infertility industry. The rate of triplet and higher-order multiples has declined over the past decade. This is largely attributed to a decreased number of embryos transferred. Nonetheless, the twin rate has remained consistently high. CONCLUSION(S): Superovulation has become a routine medical therapy used for ovulation induction and IVF. With the development of this technology have come effective therapies for infertility and new ethical and medical challenges. Since the advent of gonadotropin therapy we have already developed technologies to improve monitoring and decrease hyperstimulation and high-order multiple pregnancies. In the future we anticipate new tools devised to optimize one embryo for one singleton live birth.

Gonadotropin therapy: a 20th century relic.

Gonadotropin therapy has been a cornerstone of infertility therapy for half a century. From the very beginning, its use has been associated with a high rate of multiple births, particularly high order multiples, and ovarian hyperstimulation syndrome. Initially, success rates seemed acceptable when used for superovulation (SO)/IUI therapy. However, as data from RCTs have emerged, reported outcomes suggest that we question the use of injectible gonadotropins. This manuscript examines the studies that have challenged gonadotropin use for SO/IUI and other research that supports reduced doses of gonadotropins for IVF. We examine the challenges for its continued use for SO/IUI and for moving to lower doses worldwide for IVF. We propose a future that views gonadotropins as a relic of the twentieth century.

Clomiphene citrate utilization in the Netherlands 1998-2007.

BACKGROUND: Infertility is a growing problem in western societies. Few studies have examined the drug utilization of common treatments for infertility. Clomiphene citrate (CC) is the first-line treatment for normogonadotropic women with absent or irregular ovulation. We examined CC use among women at reproductive age in the northern Netherlands. METHODS: Drug dispensing data of CC between 1998 and 2007 were retrieved from the IADB.nl database. Two-year prevalences of CC use per 1000 women covered by the database were calculated and stratified by 5-year age group. The duration of CC use was analyzed using Kaplan-Meier survival analysis. RESULTS: From the IADB.nl database, a total of 1854 women aged 20-44 years initiated ovulation induction treatment with CC only in the northern Netherlands during 1998 and 2007. The 2-year prevalence of CC use increased from 6.66 per 1000 women during 1998-1999 to 7.24 per 1000 during 2002-2003, followed by a decrease to 4.82 per 1000 in 2006-2007 (P < 0.05). Median duration of CC use was four cycles for women <30 years of age, three cycles for women aged 30-39 and two cycles for women aged above 40. CONCLUSIONS: There is no increase of CC use during 1998-2007, and indeed a decrease of CC use during recent years, among women at reproductive age in northern Netherlands.

The use of controlled ovarian hyperstimulation (COH) in clinical in vitro fertilization: the role of Georgeanna Seegar Jones.

The use of controlled ovarian hyperstimulation (COH) to recruit multiple oocytes is now common practice worldwide in most clinical programs of in vitro fertilization (IVF). It was not always so. This is the story of the first successful use of exogenous gonadotropins in a clinical program of IVF.

The science behind 25 years of ovarian stimulation for in vitro fertilization.

To allow selection of embryos for transfer after in vitro fertilization, ovarian stimulation is usually carried out with exogenous gonadotropins. To compensate for changes induced by stimulation, GnRH analog cotreatment, oral contraceptive pretreatment, late follicular phase human chorionic gonadotropin, and luteal phase progesterone supplementation are usually added. These approaches render ovarian stimulation complex and costly. The stimulation of multiple follicular development disrupts the physiology of follicular development, with consequences for the oocyte, embryo, and endometrium. In recent years, recombinant gonadotropin preparations have become available, and novel stimulation protocols with less detrimental effects have been developed. In this article, the scientific background to current approaches to ovarian stimulation for in vitro fertilization is reviewed. After a brief discussion of the relevant aspect of ovarian physiology, the development, application, and consequences of ovarian stimulation strategies are reviewed in detail.

Changing genetic world of IVF, stem cells and PGD. A. Early methods in research.

Genetics proved essential to introduce IVF, preimplantation diagnosis (PGD) and embryo stem cells in the 1960s. Its small input in early years was confined to aspects such as timing follicle growth and ovulation. Modest understanding in the mid- to late 1980s, mostly on studies in mice, involved the actions of single genes and the balance between maternal and zygotic transcripts in preimplantation stages. Human IVF began after human oocytes were matured in vitro, and their meiotic chromosomes analysed. Their fertilization in vitro led to PGD and embryo stem cells. Unlike mouse embryos, most human embryos failed to implant, so the best had to be selected to improve IVF pregnancy rates. Initially, faster-growing embryos proved superior. Later, patterns of polarized nucleoli in pronuclei, the degree of blastomere fragmentation and growth of embryos in vitro to blastocysts provided excellent markers. Single cells could be isolated from embryos using micromanipulation. Stem cells from inner cell mass, a branch of IVF, differentiated into immortal stem cell lines in vitro if disaggregated. They formed virtually all body tissues in blastocysts cultured intact or when injected singly into recipient blastocysts. Later, the genetic controls of ES cell differentiation were assessed, together with factors switching them along specific differentiation pathways. Marker genes identified ES cells differentiating into various tissues.

IVF: past and future.

The introduction of IVF into the New World had its roots in Robert Edwards' six-week fellowship at Johns Hopkins in 1965, when he and I made a systematic attempt to fertilize human oocytes in vitro. While fertilization was not claimed in the publication of the work done in 1965, a retrospective examination of published photos indicate that human fertilization was obtained at that time. Edwards and Steptoe achieved a term birth with IVF in 1978, and this stimulated the establishment of an IVF clinic in Norfolk, Virginia. Using ovarian stimulation in 1981, the first delivery in the New World took place. This led to a series of studies on the influence of ovarian stimulation on the normal menstrual cycle and resulted in the finding that with ovarian stimulation there are three response patterns: high, normal and low. It was shown that an LH surge does not occur in ovarian stimulation. This latter observation led to the discovery of the LH surge inhibiting factor. The Norfolk programme became involved in the societal impact of IVF through an invitation to the Vatican, the Ethical Committee of the American Fertility Society (later the American Society for Reproductive Medicine), a lawsuit for libel against the local newspaper, and other activities.

Ovarian stimulation: from basic science to clinical application.

Treatment for infertility, including ovarian stimulation, was first introduced almost 100 years ago. At this time, radiation therapy became an established treatment, and it was only some decades later that the problem of radiation-induced cancer emerged. Non-human gonadotrophins, such as pregnant mare serum gonadotrophin (PMSG), and human pituitary gonadotrophins (HPG), were commonly used for hormonal stimulation procedures. However, use of PMSG led to antibody formation, and it was therefore only useful for the first treatment cycle. HPG produced good results, but its use came to an end in the late 1980s when it was linked to the development of Creutzfeldt-Jakob disease. The first hormonal product from human menopausal urine to be used was human menopausal gonadotrophin (HMG), followed later by purified preparations of this product. All of these preparations contained a high percentage of unknown urinary proteins, which interfered with batch-to-batch consistency. This changed with the introduction of recombinant gonadotrophins, produced from an immortalized/standardized mammalian cell line (CHO). More recent developments include the introduction of long-acting gonadotrophin formulations. The development of gonadotrophin-releasing hormone (GnRH) analogues and more recently the use of GnRH antagonists has helped to improve ovarian stimulation protocols by optimizing their efficacy, and making them easier to administer.