Twin Birth Rate Research Articles

Mitigating multiples, less is more: examining trends in multifetal gestation rates with assisted reproductive technology.

Multifetal gestation (MFG) is much more common in pregnancies that utilize assisted reproductive technologies (ART). We assessed how these rates have changed over the previous decade and the impact on live birth rates (LBR). This retrospective cohort study uses the National Summary Reports of the Society for Assisted Reproductive Technology (SART) from 2014 to 2020. Data points included only autologous cycles. The data were divided into five age groups as reported in the database: < 35, 35-37, 38-40, 41-42, and > 42years old. Descriptive statistics and a two-tailed T-test were used to determine the trends and statistical significance (p < 0.05). Rates of twin births decreased substantially from 2014 to 2020 for autologous embryo transfers across all age groups and diagnoses. Surprisingly, the overall LBR for autologous IVF cycles decreased at similar rates from 2014 to 2020 in all age groups. The mean number of embryos transferred has dramatically reduced, especially across age groups < 42. Rates of twin and higher-level gestations have decreased substantially over the past decade; the effect correlates with the increased utilization of eSET and PGT. The cause of infertility did not significantly impact the rate of MFG.

Desempenho reprodutivo, características da lactação e medidas biométricas de caprinos Manavlı

This study determined reproductive performance, milking traits and body measurements in 630 Manavlı goats that were reared purely in the Denizli province of Türkiye in six goat flocks. In this study, live weights and zoometrical body measurements of does and bucks were defined. Additionally, flock reproductive traits and milk yield were determined for six flocks. Overall, birth rate, twin birth rate, kidding rate and litter size in six flocks were determined as 98.34%, 43.42%, 1.41 and 1.44, respectively. The mean of the lactation milk yield, lactation period and daily milk yield were 160.48 kg, 198 days and 0.810 kg, respectively. The live weights of does ranging in age from 4.1 to 4.7 were between 74.59 and 86.30 kg, while the live weights of bucks ranging in age from 2.1 to 2.7 were between 101.19 and 118.23 kg . Some body measurements of does, such as height at withers, rump height, rump width, body length, heart girth, ear length, tail length, and front and back wrist girth, were measured as 92.80, 93.07, 22.86, 91.97, 105.02, 26.83, 20.19, 12.35 and 12.31 cm, respectively, before mating season. The same values at the abovementioned period were measured as 98.27, 98.71, 23.87, 100.48, 109.89, 26.97, 22.30, 14.46 and 14.41 cm, respectively. This study is the first research related to Manavlı goats, for which no features have been reported to date. The obtained results will help to contribute to livestock diversity.

O-093 Infant mortality after assisted reproductive technology – a Nordic collaborative study on 7,947,575 liveborn children

Abstract Study question Is infant mortality, i.e., mortality up to one year of age, higher after assisted reproductive technology (ART) than after natural conception (NC)? Summary answer Infant mortality was increased in ART-singletons vs NC-singletons, with similar increased mortality across ART fertilization methods. Infant mortality was not increased in ART-twins vs NC-twins. What is known already Children born after ART have an increased risk of poor perinatal outcomes such as preterm birth and low birth weight, mainly due to the higher twin birth rates in the ART population. ART singletons also carry an increased risk of poor perinatal outcomes as compared to their NC counterparts. Studies on consequences of being born after ART are mostly sparse and inconclusive which also applies to studies on infant mortality. Study design, size, duration A Nordic registry-based study including all children born alive in Denmark (1994–2014), Finland (1990–2014), Norway (1984–2015) and Sweden (1985–2015) resulting in a cohort of 171,836 ART-children and 7,775,739 NC-children. Among ART-children 127,248 (74%) were singletons and 42,569 (25%) twins, and among NC-children 7,576,396 (97%) were singletons and 194,775 (3%) twins. Multiples with &amp;gt;2 children were excluded (&amp;lt;0.1%). All singletons and twins were followed until death, emigration or one year of age. Participants/materials, setting, methods Data originated from national ART-, birth-, and causes of death registers. Infant mortality was compared for ART vs NC singletons and ART vs NC twins in separate analyses using Cox proportional hazards model yielding hazard ratios (HRs) with 95% confidence intervals (95% CIs). Infant mortality in singletons and twins was compared for IVF, ICSI, fresh and frozen embryo transfer vs NC counterparts. Cause-specific death analysis accounted for other causes of death as a competing risk. Main results and the role of chance Overall, 515 (4‰) ART- and 26,076 (3‰) NC-singletons and 615 (14‰) ART- and 3317 (17‰) NC-twins died during infancy. Median age at death was 3 (IQR 0–195) and 10 days (IQR 0–245) for ART- and NC-singletons, respectively, and 1 (IQR 0–151) and 2 days (IQR 0–161) for ART- and NC-twins, respectively. After adjusting for country, parity, maternal age, and birth year, the adjusted HR (aHR) for infant mortality was 1.75 (95% CI 1.60–1.91) for ART-singletons vs NC-singletons, and 0.94 (95% CI 0.86–1.03) for ART-twins vs NC-twins. A higher mortality was found consistently among ART-singletons born after IVF, ICSI, fresh embryo transfer and frozen embryo transfer vs NC-singletons. Infant mortality was consistently similar between ART-twins and NC-twins across treatment methods. Leading causes of death were conditions originating in the perinatal period (23% and 47% of deaths among singletons and twins) with aHR 1.87 (95% CI 1.65–2.12) for ART-singletons vs NC-singletons, and aHR 0.97 (95% CI 0.86–1.10) for ART-twins vs NC-twins, and congenital malformations (19% and 11% of deaths among singletons and twins) with aHR 1.31 (95% CI 1.09–1.58) for singletons and aHR 1.37 (95% CI 1.08–1.74) for ART-twins vs NC-twins. Limitations, reasons for caution Observational studies are prone to confounding. Despite adjustment for some major confounders, residual confounding from underlying parental conditions cannot be excluded. Causes of death may be more complex than the causes registered. Further, 44% of deaths among NC and 12% of deaths in ART were without an assigned cause. Wider implications of the findings Findings that infant mortality is increased among ART- vs NC-singletons corresponds with previous findings of poorer perinatal outcomes in this group. Risks were similar across ART fertilization methods and cryopreservation status. Trial registration number Not applicable

Особенности развития и психическое здоровье близнецов раннего возраста: обзор отечественных и зарубежных исследований

&lt;p style="text-align: justify;"&gt;&lt;strong&gt;Objectives. &lt;/strong&gt;Due to the increasing birth rate of twins and the high risk of delayed physical, cognitive, and psychosocial development in twins at an early age, there is a need to identify factors that contribute to the mental health and developmental trajectory of children.&lt;/p&gt; &lt;p style="text-align: justify;"&gt;&lt;strong&gt;Methods.&amp;nbsp;&lt;/strong&gt;We conducted a review and analysis of recent domestic and international research from 183 articles published between 2009 and 2024, and available in the Scopus, Semantic Scholar, PubMed, Bielefeld Academic Search Engine, Russian Science Citation Index (RSCI) and Crossref databases. The search used the keywords &amp;ldquo;infant twins&amp;rdquo;, &amp;ldquo;twins at early age&amp;rdquo;, &amp;ldquo;twins early development&amp;rdquo;, &amp;ldquo;twins interaction&amp;rdquo;.&lt;/p&gt; &lt;p style="text-align: justify;"&gt;&lt;strong&gt;Results.&amp;nbsp;&lt;/strong&gt;The interest of researchers in different aspects of the mental health and development of children born from monozygotic and dizygotic twin pregnancies is shown. The main factors affecting the health and development of twins are genetic factors, congenital defects, gestational age and birth weight, the presence of trauma during birth, as well as the somatic health of children in the first months of life. The early development of twins is closely related to the features of the care organization and parenting, interaction with the mother, as with a caring adult, a set of environmental factors and conditions for the education. At an early age, twins are at high risk of lagging in general physical, cognitive and speech impairment development compared with singleton, which should be taken into account in monitoring the need for early help for children.&lt;/p&gt; &lt;p style="text-align: justify;"&gt;&lt;strong&gt;Conclusions.&amp;nbsp;&lt;/strong&gt;There is a need for relevant domestic research on the features of the development of twins at an early age. The study of the individual trajectory of early development of each child from twins should be carried out taking into account the factor of discordance in a twin pair.&lt;/p&gt;

Iatrogenic and demographic determinants of the national plural birth increase

ObjectiveTo study the contribution of ovulation induction and ovarian stimulation, in vitro fertilization (IVF) and unassisted conception to the increase in national plural births in the U.S., a significant contributor to adverse maternal and infant health outcomes. DesignNational and IVF-assisted plural birth data were derived from the Centers for Disease Control and Prevention’s National Vital Statistics System (1967-2021, after introduction of Clomiphene Citrate in the U.S.) and the National Assisted Reproductive Technology Surveillance System (1997-2021), respectively. Main Outcome MeasuresIn addition to IVF-assisted plural births, the contributions of unassisted conception to plural births among women aged <35 and ≥35 years were estimated using plural birth rates from 1949-1966, and a Bayesian logistic model with race and age as independent variables. The contribution of ovulation induction and ovarian stimulation was estimated as the difference between national plural births and IVF-assisted and unassisted counterparts. ResultsFrom 1967-2021, the national twin birth rate increased 1.7-fold to a 2014 high (33.9/1000 live births), then declined to 31.2/1000 live births; the triplet and higher-order birth rate increased 6.7-fold to a 1998 high (1.9/1000 live births), then declined to 0.8/1000 live births. In 2021, the contribution of unassisted conception among women <35 to the national plural births was 56.1%, followed by ovulation induction and ovarian stimulation (19.5%), unassisted conception among women ≥35 (16.8%) and IVF (7.6%). During 2009-2021, the contribution of ovulation induction and ovarian stimulation has remained stable, the contribution of unassisted conception among women <35 and women ≥35 has increased, and the contribution of IVF has decreased. ConclusionOvulation induction and ovarian stimulation are leading iatrogenic contributors to plural births. They are, therefore, targets for intervention to reduce the adverse maternal and infant health outcomes associated with plural births. Maternal age ≥35 is a significant contributor to the national plural birth increase.

Production, reproduction, and some adaptation characteristics of Romanov sheep raised under humid temperate climate.

This study aimed to determine the fertility and growth traits, viability, and body measurements of the Romanov sheep under breeder conditions in the humid region of Turkey. The animal material of the research consisted of sheep imported from Ukraine in 2019. In the study, there are two farms with 31 and 44 ewes in the first year and three farms with 45, 34, and 32 ewes in the second year. The reproductive performances of 186 sheep and lambs in three different farms were examined, and nine rams, one ram per 20 sheep, were used for mating. Two-year (2020 and 2021) data on the reproductive performance of pure Romanov ewes, survivability in ewes and lambs, and development characteristics in lambs were used in the present study. The conceived rate (88.17%), fecundity at birth (1.42) and at weaning (1.29), litter size at birth (1.76) and weaning (1.56), single (50.98%), twin (41.83%), and triplet birth rate (6.54%), and abortion rate (6.71%) were determined for 2 years average. Birth and weaning weights of lambs were affected by sex and birth type (p < 0.01). The Romanov sheep and their lambs did not satisfy the breeder regarding reproductive performance and lamb development.

P-766 Re-assessment of the Belgian legislation on embryo transfer in a blastocyst transfer policy

Abstract Study question How does a multiple fresh blastocyst transfer policy impacts live birth rate (LBR) and multiple live birth rates (MLBR) in relation to maternal age ? Summary answer Fresh transferring of ≥ 2 blastocysts only increases LBR in women above the age of 36 and substantially increases risk of multiples in all age categories. What is known already Multiple pregnancies after ART are recognized as a major complication as it significantly contributes to extreme preterm and very low-birthweight births. Even in the presence of a strict Belgian embryo transfer law in some subgroups in which double embryo transfer (DET) is allowed (women aged &amp;lt;36 years in cycle rank 3 up to 6 and in women aged 36-40 years in cycle rank 2), twining rates remain above 10%. A study by Tannus et al., (2017) concluded that double blastocyst transfer (DBT) is associated with both higher LBR and higher twin birth rates compared to elective single blastocyst transfer (eSBT). Study design, size, duration A single center retrospective, observational cohort study was conducted between July 2010 and December 2020. Both fresh IVF and ICSI cycles were included. A total of 8,402 fresh transfers were performed (2,948 on day 3 and 5,454 on day 5) over the course of the study period. SET was performed in 6,108 cases, DET in 2,077 cases, triple embryo transfer (TET) in 202 cases and multiple embryo transfers (MET) in 15 cases. Participants/materials, setting, methods The primary outcomes of this study were LBR per transfer and twin pregnancy rate. Generalized estimating equations (GEE) with the patient as subject was applied to account for clustering of cycles within women. An interaction analysis between the number of embryos transferred and age categories in the day 5 group was performed. A P-value of &amp;lt; 0.05 was considered statistically significant. Main results and the role of chance In women aged &amp;lt;36 years, chances of a live birth were not significantly higher when two or more vs. a single blastocyst were transferred (OR: 1.014; 95%% CI 0.791 - 1.299; p = 0.91). However, transferring more than one blastocyst in women aged 36-40 years and &amp;gt;40 years did result in a higher chance of live birth compared to SBT (OR: 1.631; 95% CI: 1.218 - 2.185; p = 0.0008 and OR: 1.634; CI: 1.219-2.190; p = 0.0008, respectively).` Women aged 36-40 years and &amp;gt; 40 years had an estimated 19.3% and 66.3% lower odds respectively of a live birth after the transfer of a day 5 embryo, vs. women aged &amp;lt;36 years (OR: 0.800, 95% CI: 0.687-0.931; p = 0.0034 and OR: 0.337, CI: 0.268-0.424; p &amp;lt; 0.0001, respectively). Overall, live births were 28.5% higher when 2 or more blastocysts were transferred compared to an SBT (OR: 1.285 95% CI 1.1.077 – 1.533) (p = 0.0046). The estimated odds for a twin pregnancy were 17.8 times higher for DBT/MBT compared to SBT (OR 17.814; 95% CI: 10.74 - 29.55) (p &amp;lt; 0.0001). Limitations, reasons for caution This study is limited by its retrospective design and no interaction analysis between number of twin pregnancies and age categories was possible due to the low number of twins. Wider implications of the findings The data indicates that in women younger than 36 years only one blastocyst should be transferred regardless the embryo quality or the cycle rank. Only for patients older than 40 years, transfer of two blastocyst(s) could be considered. Trial registration number Not applicable

Twin birth rates and obstetric interventions in Iceland: A nationwide study from 1997 to 2018.

Twin pregnancies are associated with increased antepartum and intrapartum risks. Limited multiple embryo transfers are associated with decreased twin birth rates. We aimed to study the effect of 2009 Icelandic regulations on twin birth rates and examine obstetric intervention rates for twin births during the study period. The study included all births (N = 94 028) in Iceland during 1997-2018. Twin birth rates and obstetric intervention rates were compared over birth year periods using modified Poisson regression adjusted for confounders. An observed decrease in the twin birth rate trend was most notable from 2006 until 2009. Twin birth decreased in 2009-2013 (prevalence ratio [PR] 0.74, 95% confidence interval [CI] 0.64-0.86) and in 2014-2018 (PR 0.74, 95% CI 0.64-0.86) compared with 1997-2002. This decrease was only evident for women aged 30+ years in stratified analysis. Induction of labor rates increased from 26% in 1997-2002 to 44% in 2014-2018 (adjusted rate ratio [ARR] 2.10, 95% CI 1.72-2.57) whereas elective cesarean section (ARR 0.80, 95% CI 0.59-1.07) and urgent cesarean section (ARR 0.79, 95% CI 0.63-1.00) rates appeared to decline. Twin births decreased during the study period. International guidelines published before the Icelandic regulations may have affected twin birth rates in Iceland. Induction of labor rates for twins increased while cesarean section rates decreased.

Comparison of pregnancy outcomes between IVF-ET pregnancies and spontaneous pregnancies in women of advanced maternal age

Aim To explore the impact of IVF on pregnancy complications and birth outcomes in women of advanced maternal age. Methods In this retrospective study, 3325 women were divided into the ART pregnancy group (n = 241) and the natural pregnancy group (n = 3086). The differences in maternal general conditions, pregnancy complications and birth outcomes were compared between the two groups. Results The ART group had higher rates of primiparity (78.4% vs 20.4%), cesarean section (90.5% vs 76.2%) and twin births (28.6% vs 2.1%). The risk of gestational hypertension (5.8% vs 2.9%), preeclampsia (5.0% vs 2.3%) and preterm birth [28 ∼ 31 + 6 weeks (2.9% vs 1.1%), 32 ∼ 33 + 6 weeks (5.0% vs 1.4%), 34 ∼ 36 + 6 weeks (15.8% vs 9.4%)] was significantly higher in the ART group than in the natural pregnancy group. Neonates in the ART group had lower birth weights (2882.61 ± 657.70 vs 3223.05 ± 534.28). However, in the singleton-only comparison, only gestational hypertension still showed a statistically significant difference. Conclusions For women of advanced maternal age, IVF-ET pregnancies may result in higher rates of pregnancy complications and adverse birth outcomes, but this is likely to be due to increased rates of multiple pregnancies.

Temporal Trends in Multiple Births in Greece: The Evolution of an Epidemic.

Introduction Multiple births constitute the dominant adverse effect of fertility treatments and are associated with increased perinatal risks. The aim of this study was to comprehensively examine and present time trends in multiple births in Greece. Methods Data on live births by multiplicity were derived from the Hellenic Statistical Authority, covering a 65-year period from 1957 to 2021. Temporal trends in multiple birth rates (MBR), twin birth rates (TwBR), as well as in triplet and higher-order birth rates (Tr+BR)were assessed using joinpoint regression analysis, and the annual percentage changes (APC) were calculated with a 95% confidence interval (95% CI) and level of statistical significance (p < 0.05). Results The MBR in Greece showed a downward trend from 1957 to 1979 (APC = -1.7, 95% CI: -2.0 to -1.4, p < 0.001). However, the rate started to climb in the 1980s, accelerated during the 1990s, and continued to rise in the two most recent decades, reaching a historic high and a world record of 57.2 per 1,000 births in 2021, i.e., a 3.4-fold increase since 1985. The TwBR increased from an all-time low of 16.5 per 1,000 births in 1978 with APC = 1.4 (95% CI: 0.2 to 2.5, p = 0.021) during 1979-1989, APC = 6.3 (95% CI: 5.5 to 7.2, p < 0.001) during 1989-2001, and APC = 1.2 (95% CI: 0.8 to 1.5, p < 0.001) during the last two decades (2001-2021). The Tr+BR, after an all-time low of 17.5 per 100,000 births in 1966, increased dramatically from 1982 to 2000 (APC = 12.4, 95% CI: 9.6 to 15.2, p < 0.001), leveled off during 2000-2011, and after reaching a historic maximum of 351.1 per 100,000 births in 2010, there was a sharp decreasing trend during the last decade (2011-2021: APC = -12.1, 95% CI: -16.8 to -7.2, p < 0.001). Conclusion The dramatic increases in maternal age as well as in medically assisted conceptions have resulted in an epidemic increase in MBR in Greece reaching world record levels. During the last decade, there was an encouraging decline in the Tr+BR; however, the TwBR has continued to trend upwards.

The effect of reduced dose of PGF2α on certain reproductive parameters in awassi yearlings in anestrus synchronisation protocol following the end of the of the breeding season

The aim of this study was to investigate the effect of the administration of half or full dose of prostaglandinF2α (PGF2α; Gestavet Prost, d-cloprostenol, HIPRA®) injection in a routine synchronization protocol following theend of the breeding period including intravaginal sponge (medroxyprogesterone acetate; Espanjovet, HIPRA®) andeCG (Oviser 500, HIPRA®) on certain fertility parameters in ewes.Two hundred thirty-eight Awassi yearlings (agedone year old) divided into two groups:116 ewes received a half dose (HSDP; 37.5 μg) of PGF2α and 122 ewes receivedfull dose (FSDP;75 μg).The pregnancy rates were 67.2% and 72.1% for HSDP and FSDP, respectively (P&gt;0.05).The lambing rates were 64.7% and 63.9% for HSDP and FSDP, respectively (P&gt;0.05).The single lambing rate inHSDP(94.7%) was higher (P&lt;0.05) compared to that in FSDP (73.1%). The twin and multiple birth rates of FSDPwas higher (P&lt;0.05) than HSDP. As a result, it was inferred that aHSDP could be used in Awassi yearlings withoutexperience of lamb care and in a herd in which single lambing was preferable. Moreover, due to the fact that it is moreaffordable and not detrimentalto fertility, it was concluded that HSDPcan offer an advantage in large flocks and can beused for manipulating fecundity ratesin yearlings.

Effects of exogenous GnRH administration on lambing performance of oestrus-synchronized Kazak ewes during the breeding season.

The objective of this study was to investigate the effects of GnRH at insemination on lambing performance of Kazak ewes. Oestrus was synchronized in 774 adult Kazak ewes using an intravaginal sponge impregnated with flurogestone acetate. The sponge was left in the vagina for 12 days followed with an injection of 330 IU of eCG at sponge removal. Each ewe was inseminated twice at 48 h and 60 h after sponge removal. The treatment group (n=387) was intramuscularly injected at the first insemination with a dose of 25 μg GnRH and the control group (n=387) with saline solution. The results showed that GnRH administration significantly decreased the fertility rate. In addition, significant differences were observed between the two groups in terms of the twin birth rate, the abortion rate and the litter size. In conclusion, GnRH administration at insemination was not recommended in Kazak ewes undergoing the fixed time artificial insemination during the breeding season. The breed may be a critical determinant of the potential for the exploitation of GnRH application in sheep breeding programmes.

P-736 Twins, an instant family: beyond the risks and health in Central America

Abstract Study question Why do patients attending fertility centers in Centralamerica consider twins as the best possible outcome? Summary answer In Centralamerica patients expect to have twins after a fertility treatment. Preliminary results show that, from a specialist’s perspective, this expectation might be financially driven. What is known already Twins have fascinated humanity since early times. Every culture in the world has a different reaction to the birth of twins and has myths about them. Some myths are still present in current times and affect our decisions. After a fertility treatment, the likelihood of having twins increases, which has contributed to a worldwide increase of the twin birth rate. In spite of the risks, some patients prefer to have twins. Study design, size, duration This is a qualitative study based on anthropological theory and ethnographic research. Semi-structured interviews were conducted to infertility specialists during July of 2020 in Centralamerica. These six countries are a cultural region that shares historical and economic features which enables a socio-cultural anthropological research. The framework for the interview’s structure is the ecological paradigm from medical anthropology theory. In this paradigm the individual is seen as part of a context that influences their medical decisions. Participants/materials, setting, methods The participants were infertility specialist who had more than 3 years of experience and practice reproductive medicine in Central America. The method was a semi-structured interview via Zoom and was recorded and then transcribed with the software Transcriptions Version 1.2. The results were coded and analyzed with cognitive anthropology methods to identify cultural models in the speech. In ethical aspects, the confidentiality of the interviewee was considered important and was protected through informed consent. Main results and the role of chance The results of the interviews with infertility specialists indicate that they have difficulties explaining patients about the risks and complications of a multiple pregnancy. According to the physicians, many patients expect twins after a treatment. The patients have the idea that they will have “two for one” (“dos de un solo”) and believe that the raising of two babies will require less time and money. The birth of twins is considered a “double blessing” (“doble bendicion”) or a “double price” (“doble premio”). With one single treatment they hope to get the “ideal family” that consist of one girl and one boy (“tener la parejita”). The patients have preconceived ideas that are influenced by their environment, like family members, friends and the media. Central America was part of the mesoamerican region were maya and aztecs myths continue to influence the popular culture and people continued to believe that twins have special connections and could have a good sibling relationship. Physicians are not aware that the media and family have so much weight in the medical decisions of their patients only focus on the fact that patients underestimate the risks. Limitations, reasons for caution The reason for caution is that this is a local study that cannot be generalized in time and place. Wider implications of the findings The results would help to design interviews for patients with the final purpose of understanding their perceptions and attitudes toward twins. In a region with no public health policies regarding infertility treatments, the results can improve communication between the doctors and patients to reduce twin rates. Trial registration number (')

Comparison of the effect of Gonadotropin-Releasing Hormone and Human Chorionic Go3nadotropin on Reproductive Performance of Romanov Ewes During the Natural Breeding Season.

Low pregnancy rate is an important issue in small ruminants. Superovulation protocols would serve as the possible techniques to increase the pregnancy rate in small ruminants due to the use of synthetic hormones. The present study aimed to assess the effect of gonadotropin-releasing hormone (GnRH) and Human chorionic gonadotropin (hCG) after artificial insemination (AI) on the pregnancy rate of Romanov ewes breed. To this end, estrus was synchronized in 140 ewes using a controlled internal drug-releasing (CIDR) device. Following CIDR removal, all ewes received 400 IU Pregnant Mare's Serum Gonadotropin (PMSG). The ewes were assigned to three groups (control, n=20; experimental groups, each of them was divided into three subgroups, n=20). The first group in each experiment was assumed as control. The second and third groups received three levels of GnRH, (400, 500, and 600 µg, n=20) and hCG (200, 300, and 400 IU) administered by the intramuscular (IM) route. As soon as the signs of estrus were observed, the ewes were isolated from the others and artificially inseminated with fresh sperm using the transcervical method. The results indicated that there were no significant differences between experimental groups in ovulation and pregnancy rates on days 33 and 90 post-AI (P>0.05). The highest twin birth rate (20%) was recorded in the hCG group (300 IU), as compared to GnRH and control groups (P<0.05). The effect of GnRH and hCG on the plasma concentration of progesterone was significant (P<0.01). The groups significantly differed in fecundity rate (Single birth, twin birth, and triple birth) (P<0.05), all of these parameters were significantly higher in the hCG 300 IU group. It can be concluded that the injection of 300 IU of hCG hormone after insemination improves pregnancy rate in ewes.

Factors affecting fertility traits and milk yield of Holstein cattle with different origins raised in Trakya region

This study was conducted with Holstein heifers imported from the United States (US), Germany, and the Czech Republic to a private dairy farm in Kırklareli/Lüleburgaz region in Turkey to evaluate their adaptation in terms of milk production and fertility performance. The first insemination age of the herd was 490.62 days, and the first calving age was 804.24 days. The number of inseminations required per pregnancy was calculated as 3.99, gestation length as 279.72 days, and service period as 213.99 days. The rate of abortion and twin births were higher in those of US origin. Increased first calving age was observed in heifers of German origin due to delayed insemination. The mean actual lactation milk yield in the first lactation periods was 11834.75 Lt, 305 days milk yield was 8573.31 Lt, lactation length was 419.61 days, the dry period was 63.02 days. Milk yield performance of Holsteins of US origin was higher in the first lactation period. In conclusion, milk production was profitable; however, the fertility performance of the herd was poor in general. Poor fertility performance was due to poor herd management and adaptation problems. Therefore, after the calving period, more attention should be paid to oestrus monitoring and insemination activities. In Turkey, the success of live animal imports should be well investigated; in particular, problems occurring during animal selection for importation should be evaluated, and short-/long-term national strategies should be developed.

Assessment of Twin Fetal Exposure to Environmental Magnetic and Electromagnetic Fields.

Fetal development is vital in the human lifespan. Therefore, it is essential to characterize exposure by a series of typical environmental magnetic and electromagnetic fields. In particular, there has recently been a sharp increase in the twin birth rate. However, lack of appropriate models has prohibited dosimetric evaluation, restricting characterization of the impact of these environmental factors on twins. The present study developed two whole-body pregnant models of 31 and 32 weeks of gestation with twin fetuses and explored several typical exposure scenarios, including 50-Hz uniform magnetic field exposure, local 125-kHz magnetic field (MF), and 13.56-MHz electromagnetic field exposure, as well as wideband planewave radiofrequency (RF) exposure from 20 to 6000 MHz. Finally, dosimetric results were derived. Compared to the singleton pregnancy with similar weeks of gestation, twin fetuses were overexposed at 50-Hz uniform MF, but they were probably underexposed in the RF scenarios with frequencies for wireless communications. Furthermore, the twin fetuses manifested large dosimetric variability compared to the singleton, which was attributed to the incident direction and fetal position. Based on the analysis, the dosimetric results over the entire gestation period were estimated. The results can be helpful to estimate the risk of twin-fetal exposure to electromagnetic fields and examine the conservativeness of the international guidelines.© 2022 Bioelectromagnetics Society.

Perinatal Risks of Twin Pregnancies and Births-Data for the Decision-Making Process Prior to Double Embryo Transfer

The incidence of multiple pregnancies has increased due to Assisted Reproductive Techniques (ART) in the last decades. National data of the German birth registry show that before ART was introduced, the twin birth rate was 10 of 1,000 births.

Clinical data analysis of nine years of experience with twin pregnancy: a tertiary hospital-based retrospective study

Background: The incidence of twin pregnancy has been increasing worldwide and in China. This study provided a comprehensive analysis of the clinical data of twins in a Chinese tertiary hospital and summarized the clinical characteristics. Methods: A retrospective collection of data was carried out for 717 cases of twins in the Obstetrics Department of the First Affiliated Hospital of Xi’an Jiaotong University from 2011 to 2020. A comprehensive analysis of baseline information and maternal and perinatal outcomes was conducted, and the twin birth rate of the study population was also calculated. Results: The average twin delivery rate was 2.61%. A total of 206 cases were monochorionic, and 511 cases were dichorionic. Premature delivery, hypertensive disorder complicating pregnancy and premature rupture of membranes were the three most common complications. Caesarean section rates from 2011 to 2019 were maintained at 70%–80%. A total of 144 cases (20.08%) of 717 twin cases were complicated twins. Birthweight discordance ≥25% accounted for 13.53% of cases. Adverse neonatal outcomes with higher incidences were neonatal respiratory distress syndrome, small for gestational age and 1 min Apgar score ≤7. Conclusions: Twin pregnancy has different and unique clinical features. Obstetricians should pay close attention to its clinical management to obtain better perinatal outcomes.

Some Fertility Traits and Growing Characteristics of Kivircik Sheep Breed in the Extensive Farm Conditions

In this study, fertility properties and growth traits of Kivircik sheep breed have investigated in Manisa province of Turkey. Fertility properties such as lambing rate, single birth rate, twins rate, litter size, vital rate and growth traits like birth weight, 30 days, 60 days, 120 days weights have calculated and distribution of growth traits according to sex and birth type has analyzed. In the first year of the trial; pregnancy rate, one birth rate, twin rate, litter size, survival rate has determined respectively 92.2%, 69.4%, 30.6%, 1.32 and 85.1%. In the same year, average birth weights of Kivircik male and female lambs are 4.08±0.74 kg and 3.93±0.69 kg, 30. day weights are 10.57±2.83 kg and 9.83±2.73 kg, 60. day weights are 21.32±10.36 kg and 19.66±5.46 kg, 120. day weights are 31.36±7.73 kg and 28.49±6.44 kg. In the second year of the trial; pregnancy rate, one birth rate, twin rate, litter size, survival rate has determined respectively 94.9%, 95.8%, 4.02%, 1.04 and 88.8%. In the same year, average birth weights of Kivircik male and female lambs are 4.22±0.91 kg and 4.00±0.73 kg, 30. day weights are 11.37±2.25 kg and 10.69±2.09 kg, 60. day weights are 22.75±4.49 kg and 21.37±4.18 kg, 120. day weights are 38.40±9.13 kg and 34.37±7.56 kg. At the end of the trial, fertility traits except twin birth rate and litter size has determined higher in II. year than I. year. This is likely due to higher live weight before mating and better herd management. Both two years, there were significant differences between growth traits (birth weight, 30 days weight, 60 days weight and 120 days weight) and sex or birth type.

Higher Rates of Twinning Among Repeat Vs First-Time Teenage and Young Adult Mothers in the United States, 2009-2018.

Few studies examining predictors of twinning consider younger mothers who do not use assisted reproductive technologies (ART). Higher parity is associated with greater odds of having a twin birth, but it is unclear whether this association is present among young women. We tested the hypothesis that the rates and odds of twinning would increase with parity among teenage and young adult mothers who did not use ART. We conducted a retrospective, population-based cohort study using 2009-2018 United States National Vital Statistics data on 11,383,370 (58.94% first, 41.06% repeat) births to adolescent and adult women aged 15-24 years. None. Rates and odds of twinning by parity among teenage (15-19 years) and young adult (20-24 years) mothers. The adjusted twin birth rate among first-time teenage mothers was 13.28 per 1000 births compared to 16.62 twins per 1,000 births among repeat teenage mothers. This difference by parity was present but smaller among mothers aged 20-24 (18.31 vs 21.44 twins per 1000 births for first-time and repeat young adult mothers, respectively). Repeat young mothers, particularly teenage mothers, are a high-risk group in terms of infant and maternal health outcomes; their higher rate of twinning puts them at an additional risk for adverse birth outcomes. Practitioners may counsel young mothers at risk for subsequent unintended pregnancy on elevated risk of twinning.