Controlled ovarian stimulation should not be preferred for male infertility treated with intrauterine insemination: a retrospective study.

BACKGROUND: Some studies have stated that intrauterine insemination (IUI) with controlled ovarian stimulation (COS) might increase the pregnancy rate, while others suggest that IUI in the natural cycle (NC) should be the first line of treatment. It remains unclear whether it is necessary to use COS at the same time when IUI is applied to treat isolated male factor infertility. Thus, we aimed to investigate efficacy of IUI with COS for isolated male factor infertility. METHODS: A total of 601 IUI cycles from 307 couples who sought medical care for isolated male factor infertility between January 2010 and February 2020 were divided into two groups: NC-IUI and COS-IUI. The COS-IUI group was further divided into two subgroups according to the number of pre-ovulatory follicles on the day of HCG: cycles with monofollicular development (one follicle group) and cycles with at least two pre-ovulatory follicles (≥ 2 follicles group). The IUI outcomes, including clinical pregnancy, live birth, spontaneous abortion, ectopic pregnancy, and multiple pregnancy rates were compared. RESULTS: The clinical pregnancy, live birth, spontaneous abortion, and ectopic pregnancy rates were comparable between the NC-IUI and COS-IUI group. Similar results were also observed among the NC-IUI, one follicle, and ≥ 2 follicles groups. However, with respect to the multiple pregnancy rate, a trend toward higher multiple pregnancy rate was observed in the COS-IUI group compared to the NC-IUI group (8.7% vs. 0, P = 0.091), and a significant difference was found between the NC-IUI and ≥ 2 follicles group (0 vs. 16.7%, P = 0.033). CONCLUSION: In COS cycles, especially in those with at least two pre-ovulatory follicles, the multiple pregnancy rate increased without a substantial gain in overall pregnancy rate; thus, COS should not be preferred in IUI for isolated male factor infertility. If COS is required, one stimulated follicle and one healthy baby should be the goal considering the safety of both mothers and foetuses.

Projecting future utilization of medically assisted fertility treatments.

This study estimates the future utilization of medically assisted fertility treatments in Australia, focusing on assisted reproductive technologies (ARTs), intrauterine insemination (IUI), and ovulation induction. A multistate cohort component population projection model is used to determine future fertility rates from 2016 to 2026 by age and education level. These are combined with information on recent trends in use and success rates to indirectly estimate future age-specific probabilities of fertility treatment utilization. The number of ART cycles is expected to increase by 61 per cent between 2016 and 2026 if treatment success rates remain at 2015 levels, or by 34 per cent if recent improvements in ART success rates continue. The model also predicts that numbers of IUI cycles and ovulation induction cycles will decrease by 17 and 3 per cent, respectively. This research confirms the importance of including both technological improvements and socio-demographic changes when predicting future fertility treatment utilization.

Recent Advances in Boar Sperm Cryopreservation: State of the Art and Current Perspectives.

While sperm cryopreservation is the best technology to store boar semen for long-term periods, only 1% of all artificial inseminations (AI) conducted worldwide are made using frozen-thawed boar sperm. With the emergence of long-term extenders for liquid storage, the use of cryopreserved sperm in routine AI is less required. However, banks of boar semen contain cryopreserved sperm and planning inseminations in AI centres may benefit from the use of frozen-thawed semen. Therefore, there is an interest in the use of this technology to preserve boar sperm. In this regard, although the first attempts to cryopreserve boar semen date back to the seventies and this technology is still considered as optimal, some relevant improvements have been made in the last decade. After giving a general picture about boar sperm cryodamage, the present review seeks to shed light on these recent cryopreservation advances. These contributions regard to protein markers for predicting ejaculate freezability, sperm selection prior to start cryopreservation procedures, additives to freezing and thawing extenders, relevance of the AI-technique and insemination-to-ovulation interval. In conclusion, most of these progresses have allowed counteracting better boar sperm cryodamage and are thus considered as forward steps for this storage method. It is also worth noting that, despite being lower than fresh/extended semen, reproductive performance outcomes following AI with frozen-thawed boar sperm are currently acceptable.

Sperm Encapsulation from 1985 to Date: Technology Evolution and New Challenges in Swine Reproduction.

In the last 30 years, encapsulation technology has been applied to different species to minimize the loss of spermatozoa after artificial insemination. In particular, the vehiculation of boar sperm cells in barium alginate membrane has proved a valid strategy to reduce the risk of polyspermy and optimize in vivo fertilizing yields. Controlled release of male gametes into the female genital tract has reduced the minimum fertilizing dose of spermatozoa. Notwithstanding these results, encapsulation has not yet reached commercial application, largely due to the additional costs of production. However, encapsulation could be useful in advanced reproductive technology, such as sex sorting, to store sorted boar semen. The controlled release of flow cytometrically sorted spermatozoa could be a promising strategy to reduce the number of cells necessary for each insemination and hence allow the widescale use of sex sorting in this species.

Does ovarian stimulation benefit ovulatory women undergoing therapeutic donor insemination?

OBJECTIVE: To compare clinical and ongoing pregnancy after natural cycle (NC) intrauterine insemination (IUI) versus ovarian stimulation (OS) IUI in ovulatory women undergoing therapeutic donor insemination (TDI). DESIGN: Retrospective cohort. SETTING: Single infertility center. PATIENT(S): A total of 76,643 IUI cycles in patients treated with intrauterine insemination were examined. Women undergoing TDI in the absence of diagnosed female factor infertility were included. INTERVENTION(S): NC TDI or OS TDI with either clomiphene citrate or letrozole. MAIN OUTCOME MEASURE(S): Clinical and ongoing pregnancies were analyzed by generalized estimating equations adjusting for age, body mass index, total motile sperm at time of insemination and cycle number. Ongoing multiple gestations were examined as a secondary outcome. RESULT(S): Six thousand one hundred ninety-two TDI cycles from 2,343 patients (711 patients without repeated IUI cycles) met inclusion criteria and were available for analysis (3,837 NC and 2,355 OS). There was no difference in mean age between the two groups (NC, 34.2 years vs. OS, 34.3 years). Probability of clinical and ongoing pregnancy was higher in the OS cohort compared with the NC cohort (OS, 22.4% vs. NC, 18.7% and OS, 15.4% vs. NC, 14.9%, respectively). However, OS significantly increased ongoing multiple gestations (OS, 10.8% vs. NC, 2.4%). CONCLUSION(S): Ovarian stimulation in TDI cycles resulted in a <4% increase in clinical and <1% increase in ongoing pregnancy, and more than fourfold increase in ongoing multiple gestations. Natural cycle IUI should be considered as a first-line treatment for ovulatory women who need donor insemination.

Relationship between semen regurgitation and pregnancy rates with intrauterine insemination.

OBJECTIVE: To evaluate the relationship between semen regurgitation and intrauterine insemination (IUI) outcomes. We hypothesized that clinical pregnancy rates and live birth rates would be reduced when regurgitation occurred. DESIGN: Retrospective cohort study. SETTING: A university-based reproductive endocrinology and infertility clinic. PATIENT(S): Retrospective review of 1,957 IUI cycles performed on 660 patients between July 2007 and May 2012. INTERVENTION(S): None. MAIN OUTCOME MEASURE(S): The primary outcome was live birth. Secondary outcomes were positive serum pregnancy result and clinical pregnancy. Risk ratios (RRs) and 95% confidence intervals (CIs) were calculated using a cluster-weighted generalized estimating equations method to estimate modified Poisson regression models with robust standard errors to account for multiple IUI cycles in the same patient. RESULT(S): Live birth rates were similar in IUI cycles with and without regurgitation (6.3% vs. 6.8%, respectively, RR = 0.82, 95% CI [0.53-1.26]). Clinical pregnancy rates in the presence or absence of regurgitation were 10.5% vs. 10.0% (RR = 0.99, 95% CI [0.73-1.35]). Positive serum pregnancy tests after IUI did not differ by regurgitation status (15.0% vs. 15.4%, RR = 0.97, 95% CI [0.75-1.24]). Results were unchanged when adjusted for covariates (age, race and ethnicity, body mass index, duration of infertility, medication, infertility diagnosis, total motile count, and method of sperm preparation). CONCLUSION(S): The presence of regurgitation during the IUI procedure is not related to pregnancy outcome.

Does empiric superovulation improve fecundity in healthy women undergoing therapeutic donor insemination without a male partner?

OBJECTIVE: To evaluate whether superovulation improves fecundity in women undergoing therapeutic donor insemination (TDI). DESIGN: Retrospective cohort study. SETTING: University-affiliated fertility clinic. PATIENT(S): Healthy women aged 23-45 years with no history of or risk factors for infertility who underwent 152 medicated and 104 unmedicated TDI cycles from 2013 to 2018. INTERVENTION: Unmedicated TDI versus use of medication in a TDI cycle (clomiphene citrate or letrozole). MAIN OUTCOME MEASURE(S): Cumulative probability of pregnancy in six TDI cycles. RESULT(S): In adjusted all-cycle analysis, medicated TDI cycles were less likely to result in pregnancy compared with unmedicated cycles. The incidence of twins was 23% in the medicated group and 0% in the unmedicated group. Medicated cycles were less likely to result in pregnancy in women younger than 40 years or with an antimüllerian hormone (AMH) level >1.2. After three cycles not resulting in pregnancy, the only women who conceived were those who crossed over from an unmedicated to a medicated cycle (12% vs. 0%). CONCLUSION(S): Patients undergoing unmedicated TDI cycles had higher fecundity and no incidence of twin gestations. Older women, those with low AMH, and those who fail to conceive after three unmedicated cycles may benefit from medication.

Comparison of pregnancy outcomes following intrauterine insemination in young women with decreased versus normal ovarian reserve.

OBJECTIVE: To evaluate pregnancy outcomes following intrauterine insemination (IUI) in young women with low ovarian reserve compared to age-matched controls. DESIGN: Retrospective cohort SETTING: Single infertility center (July 2001-August 2018) PATIENT(S): Patients <35 years of age undergoing at least one IUI cycle with a documented serum anti-Müllerian hormone (AMH) level, patent fallopian tubes, and total motile sperm count of ≥10 million at the time of IUI. INTERVENTION(S): None MAIN OUTCOME MEASURE(S): The primary outcome was the presence of a positive serum hCG pregnancy test (>2 mIU/mL) obtained 2 weeks after the IUI procedure. Secondary outcomes included the incidence of live birth, biochemical loss, clinical miscarriage, and ectopic pregnancy. Additionally, cumulative reproductive outcomes including up to seven IUI cycles were calculated and compared between groups. RESULTS: A post-hoc power calculation demonstrated that the study sample size yielded >80% power to detect a 7% difference between groups in the primary outcome. There were 3019 patients included: 370 with AMH <1.0 ng/mL and 2649 with AMH ≥1.0 ng/mL. When adjusting for IUI treatment strategy, number of dominant follicles at time of IUI and body mass index, no difference in per-cycle or cumulative reproductive outcomes was identified between patients with low AMH (<1.0 ng/mL) and normal AMH (≥1.0 ng/mL). Analyses by treatment strategy also showed no difference in reproductive outcomes. CONCLUSION: Young patients (<35 years of age) with diminished ovarian reserve conceived as often and had per-cycle and cumulative pregnancy outcomes similar to those of age-matched controls after IUI, regardless of treatment strategy.

Post-cervical artificial insemination in porcine: The technique that came to stay.

The porcine industry is of great importance worldwide, and so any technological innovation in one or more of the associated production areas is of interest for meat production. Among such innovations in the reproduction area, post-cervical or intrauterine artificial insemination (PCAI) has emerged as a new approach in artificial insemination (AI). PCAI is gradually replacing traditional cervical insemination (CAI), particularly in countries with intensive pig production industries. This type of insemination, which deposits the semen in the body of the uterus (as opposed to traditional cervical deposition), is increasingly used in the field due to its simplicity and the numerous advantages that it provides at production level (e.g. reduced number of sperm, less time required to perform insemination and faster genetic improvement) and, consequently, from an economic point of view. In addition, since its inception, PCAI has been combined with other reproductive biotechnologies, such as the use of frozen-thawed sperm, fixed-time AI or sperm-mediated gene transfer. However, despite its wide acceptance and application, new approaches for increasing the efficiency of PCAI are constantly being sought, such as the adjustment and standardization in sperm numbers, the conservation of the PCAI semen dose, its association with other biotechnologies (sex-sorted sperm) or its efficacy in young (nulliparous and primiparous) females.

Spermatozoa Cryopreservation: State of Art and Future in Small Ruminants.

The cryotolerance of farm animal spermatozoa varies according to their specific features, such as size, shape, and lipid composition. Thus, it is impossible to develop a standardized freezing procedure for different kinds of livestock species. The establishment of an efficient semen cryopreservation procedure will facilitate long-term conservation of small ruminant genetic resources and extension of artificial insemination in daily production. Different from sheep, goat seminal plasma contains a phospholipase, which can affect spermatozoa viability through interaction with milk or egg yolk. Currently, soybean lecithin is a viable alternative that replaces the components of animal origin in freezing extenders for goat semen. In addition, vitrification or freeze-drying may act as another alternative to replace traditional cryopreservation. However, these two methods, especially freeze-drying, may require the aid of the intracytoplasmic spermatozoa injection technology. Furthermore, the cryoinjury mechanism of mammalian spermatozoa has remained unclear until now. The emergence of proteomics and transcriptomics may provide some inspiration concerning this problem. In this review, we summarize the state of art relating to small ruminant semen cryopreservation, mainly focusing on the current status of the freezing procedures. In the meantime, some highlights such as protectants, vitrification, and freeze-drying are also reviewed. Finally, the future perspectives in the field of small ruminant spermatozoa preservation are discussed.

Cryopreservation of boar semen and its future importance to the industry.

Whereas AI has arguably been the most important management tool leading to improved herd productivity, long-term storage of semen brings forth additional advantages to producers of agriculturally important animals and the AI industry. Semen cryopreservation greatly facilitates the distribution of agriculturally desirable genes, rapidly increasing herd productivity. Of particular importance to the pig industry, the use of frozen semen would help to control transmission of certain pathogens, thereby protecting the health status of the herd. Moreover, a reserve of cryopreserved semen would minimize the effects of a sudden outbreak of a contagious illness or a natural disaster. Successful cryopreservation of boar semen is necessary for international sales. Finally, effective gene banking depends on the availability of functional, cryopreserved germplasm. Despite these potential advantages of long-term semen storage, porcine sperm are notoriously sensitive to cold temperatures, and frozen-thawed semen is not routinely used by the industry. The objective of our laboratories is to develop protocols for efficient long-term storage of porcine semen using cryopreservation. We hypothesize that since the sperm plasma membrane is the primary site of cold-induced damage, reinforcing the membranes with molecules having particular properties, such as cholesterol, will improve the ability of boar sperm to withstand cold temperatures and cryopreservation protocols. Based on our data, such approaches should help alleviate the problems with sperm function after cooling, thereby resulting in better survival and motility characteristics, and reduced non-regulated capacitation and spontaneous acrosome reactions.

Ovarian stimulation in infertile women treated with the use of intrauterine insemination: a cohort study from China.

OBJECTIVE: To study the effectiveness of different ovarian stimulation protocols compared with natural cycle treatment in an intrauterine insemination (IUI) program. DESIGN: Retrospective cohort study. SETTING: Large reproductive medicine center. PATIENT(S): Couples with unexplained or mild male-factor infertility. INTERVENTION(S): Couples were treated with the use of natural-cycle IUI, or IUI after ovarian stimulation with the use of clomiphene citrate (CC), letrozole, or gonadotropins. MAIN OUTCOME MEASURE(S): Live birth, multiple pregnancy rates, and cumulative live birth rates after three IUI cycles. RESULT(S): We performed 14,519 IUI cycles in 8,583 couples. Compared with natural-cycle IUI (6.2%), live birth rates were significantly higher in IUI cycles stimulated with the use of CC (8.9%), letrozole (9.4%) and gonadotropins (9.5%). The multiple pregnancy rate resulting from natural cycles was 0.7%, compared with 4.6% in CC cycles, 1.3% in letrozole cycles, and 4.2% in gonadotropin cycles. Cumulative live birth rates after three IUI cycles were 18.4% after natural-cycle IUI, and 25.7%, 26.2%, and 23.7% with the use of CC, letrozole, and gonadotropins, respectively. CONCLUSION(S): In an IUI program for unexplained or mild male-factor infertility, ovarian stimulation with letrozole may significantly increase live birth rates while controlling multiple pregnancy rates.

Major advances in globalization and consolidation of the artificial insemination industry.

The artificial insemination (AI) industry in the United States has gone through many consolidations, mergers, and acquisitions over the past 25 yr. There are 5 major AI companies in the United States today: 3 large cooperatives, 1 private company, and 1 public company. The latter 2 have majority ownership outside of the United States. The AI industry in the United States progeny-tests more than 1,000 Holstein young sires per year. Because healthy, mature dairy bulls are capable of producing well over 100,000 straws of frozen semen per year, only a relatively small number of bulls are needed to breed the world's population of dairy cows. Most AI companies in the United States do not own many, if any, females and tend to utilize the same maternal families in their breeding programs. Little differences exist among the selection programs of the AI companies in the United States. The similarity of breeding programs and the extreme semen-production capabilities of bulls have contributed to difficulties the AI companies have had in developing genetically different product lines. Exports of North American Holstein genetics increased steadily from the 1970s into the 1990s because of the perceived superiority of North American Holsteins for dairy traits compared with European strains, especially for production. The breeding industry moved towards international genetic evaluations of bulls in the 1990s, with the International Bull Evaluation Service (Interbull) in Sweden coordinating the evaluations. The extensive exchange of elite genetics has led to a global dairy genetics industry with bulls that are closely related, and the average inbreeding level for the major dairy breeds continues to increase. Genetic markers have been used extensively and successfully by the industry for qualitative traits, especially for recessive genetic disorders, but markers have had limited impact for quantitative traits. Selection emphasis continues to migrate away from production traits and towards nonproduction traits, especially towards health and fitness traits. Specifically, fertility has arguably become the major breeding and management issue facing dairy farmers today. Some producers have implemented crossbreeding programs in an effort to capitalize on heterosis, and crossbreeding will almost certainly need to be a bigger part of the AI companies business in the years ahead.

Evaluation of intrauterine insemination practices: a 1-year prospective study in seven French assisted reproduction technology centers.

OBJECTIVE: To determine the best practices of intrauterine insemination with the partner's fresh sperm. DESIGN: Prospective multicenter observational study. SETTING: Assisted reproduction technology (ART) centers. PATIENT(S): Seven hundred and seven patients entering the program, regardless of age or cause of infertility. INTERVENTION(S): Intrauterine insemination by standard procedures. MAIN OUTCOME MEASURE(S): Effect of patient characteristics (duration of infertility, indications, age, parity, body mass index, semen parameters) as well as IUI parameters on delivery rates per couple or per attempt. RESULT(S): The overall live birth rate was 11.4% per cycle, varying from 8.4% to 17.6% between centers. The main differences in practice that had a statistically significant impact on the delivery rate were the use of gonadotropin-releasing hormone (GnRH) antagonists (15.2% with versus 9.4% without) and the number of mature recruited follicles (9.4% for one versus 15.2% for two). CONCLUSION(S): Our results indicate that the use of GnRH antagonists has a positive effect on the delivery rate, especially in the multifollicular stimulations that are required when women are older than 27 years.

Predictors of pregnancy and live-birth in couples with unexplained infertility after ovarian stimulation-intrauterine insemination.

OBJECTIVE: To identify baseline characteristics of couples that are likely to predict conception, clinical pregnancy, and live birth after up to four cycles of ovarian stimulation with IUI in couples with unexplained infertility. DESIGN: Secondary analyses of data from a prospective, randomized, multicenter clinical trial investigating pregnancy, live birth, and multiple pregnancy rates after ovarian stimulation-IUI with clomiphene citrate, letrozole, or gonadotropins. SETTING: Outpatient clinical units. PATIENT(S): Nine-hundred couples with unexplained infertility who participated in the Assessment of Multiple Intrauterine Gestations from Ovarian Stimulation clinical trial. INTERVENTION(S): As part of the clinical trial, treatment was randomized equally to one of three arms and continued for up to four cycles or until pregnancy was achieved. MAIN OUTCOME MEASURE(S): Conception, clinical pregnancy, and live-birth rates. RESULT(S): In a multivariable logistic regression analysis, after adjustment for other covariates, age, waist circumference, income level, duration of infertility, and a history of prior pregnancy loss were significantly associated with at least one pregnancy outcome. Other baseline demographic and lifestyle characteristics including smoking, alcohol use, and serum levels of antimüllerian hormone were not significantly associated with pregnancy outcomes. CONCLUSION(S): While age and duration of infertility were significant predictors of all pregnancy outcomes, many other baseline characteristics were not. The identification of level of income as a significant predictor of outcomes independent of race and education may reflect differences in the underlying etiologies of unexplained infertility or could reveal disparities in access to fertility and/or obstetrical care. CLINICAL TRIAL REGISTRATION: NCT01044862.

French field results (1985-2005) on factors affecting fertility of frozen stallion semen.

Results on procedures for freezing stallion semen and the subsequent fertility during 20 years are presented. The present system applied in French National Stud includes: (1) a freezing protocol (dilution in milk, centrifugation and addition of freezing extender (INRA82+egg yolk (2%, v/v)+glycerol (2.5%, v/v) at 22 degrees C, a moderate cooling rate to 4 degrees C and freezing at -60 degrees C/min in 0.5-ml straws); (2) selection of ejaculates showing post-thaw rapid motility >35%; and (3) an insemination protocol (mares examined once daily, two AI of 400 x 10(6) spermatozoa 24 h apart before ovulation, sufficient number of straws to have the possibility to perform six AI of 400 x 10(6) total spermatozoa, i.e. 2.4 x 10(9) total spermatozoa available per mare per season). This system was applied to >110 stallions per year, the average post-thaw motility of ejaculates was 50% (>1800 ejaculates) before selection. The semen freezability was defined as the number of selected ejaculates divided by the total number of ejaculates frozen. Of the stallions, 5, 4, 5, 21 and 64% had semen freezability of 0-10, 10-33, 33-60, 60-90 and over 90%, respectively. Per-cycle pregnancy rate was 45-48% (>1500 mares per year, 1.8 cycles per mare) and foaling rate 64%. In comparison, per-cycle pregnancy rate and foaling rate of mares hand-mated to stallions were 57-59% and 64%, respectively. The average number of straws used was 32-35 (1.75 x 10(9) total spermatozoa) per mare per season. According to our results and the literature, the most important factors for improving fertility of frozen equine semen include: (1) a low concentration of glycerol (2-3.5% final concentration); (2) a suitable base extender for freezing like Lactose-Glucose EDTA or INRA82; (3) a post-thaw motility >30-35%; and (4) a sufficient number of spermatozoa per mare per season (1.5-2 x 10(9) total spermatozoa for two to three cycles) divided into small units. Numbers of spermatozoa, lower than 750.10(6) total spermatozoa per cycle, could result in lower per-cycle pregnancy rate with higher additional costs for management of mares. Because there are no particular regulations on quality and quantity of equine semen in the European Community, there is a need for the uniformity of information about frozen semen. A codification is suggested, based on the number of spermatozoa available per mare per season, the post-thaw motility and the final glycerol concentration.

Donor insemination--a look to the future.

In this article we have reviewed many aspects of donor insemination. The deficiencies in the screening of semen donors especially for sexually-transmitted diseases has been discussed and importance of a rational protocol for recruitment and screening of potential donors has been emphasized. Factors influencing the success and outcome of donor insemination have been reviewed with particular emphasis on providing prognostic guidelines to potential donor insemination couples as to the success and outcome of the treatment. The importance of accurate timing of inseminations in determining the success of donor insemination has also been discussed. However, as has been highlighted throughout this review, there is a lack of specific prospective controlled trials, which are clearly necessary to answer specific important questions. Also emphasized has been the need of these trials to answer such basic questions as the influence of accurate timing on conception rates in specific groups of insemination recipients.

Artificial insemination: the state of the art.

The history of research into artificial insemination (AI) is over two centuries old and its commercial application now spans 75 years. It is appropriate to reflect on the contribution of this powerful method of gene dispersal. AI remains as one of the most important assisted reproductive technologies. The three cornerstones for its application are: it is simple, economical and successful. The importance of AI will be challenged in the next few decades. The remarkable progress made in other assisted reproductive technologies does have the potential to rapidly generate offspring. The challenge for any of these reproductive technologies to attain widespread use is to match AI in being simple, economical and successful. This review aims at capturing the salient advances in AI, the comparisons with natural mating and other reproductive technologies, and, whether the future of AI will be challenged. It predicts what the new horizon looks like and the role that AI will play in the overall reproductive technologies landscape.

[Insemination: history and state of the art in animals]. / L'insémination: historique, état des lieux chez l'animal.

Insemination has been used since 1950 in the bovine and since the seventies in other domestic species. The use of insemination varies between the different species in terms of activity and method. The methods depend on the anatomical and physiological characteristics of each species, which lead to different sites of semen deposition and different minimal numbers of inseminated spermatozoa to obtain efficient fertility results. The use of frozen semen influences also the methods of insemination. Intra-uterine insemination is principally used when only small quantities of semen are available and/or to reduce the number of inseminated spermatozoa. Recent results in different species indicate that the use of intra-uterine insemination could be developed in the next years.

[Multiples births: a continuing problem with assisted reproductive techniques]. / Meerlingen: een blijvend probleem bij kunstmatige voortplantingstechnieken.

Assisted reproductive techniques (ART) such as in vitro fertilisation (IVF), ovulation induction and superovulation followed by insemination have caused a sharp increase in multiple birth prevalence rates. The perinatal morbidity of multiple birth infants is high because of the high incidence of premature birth. The social and psychological problems of multiple birth families are also considerable. In 1990 high-order multiple births were mainly the result of IVF. Although the number of IVF treatments has increased more than the number of other ART treatments, nowadays high-order multiple births are predominantly caused by superovulation. Since 1990 the number of high-order multiple births has stabilised, but the recent sharp increase in ART twins results in a further rise in births of severely preterm ART infants. More restraint should be practised in superovulation treatments to bring down the number of (high-order) multiple births.