Vanishing twin syndrome among ART singletons and pregnancy outcomes

Comparison of miscarriage rates in low prognosis patients according to the POSEIDON criteria

OBJECTIVE

The POSEIDON criteria stratified patients with poor ovarian response into four subgroups with exclusive characteristics and assisted reproductive technology success rates. However, limited studies focused on miscarriage in the POSEIDON population. This study aimed to explore whether the miscarriage rate different among low prognosis patients according to POSEIDON criteria.

MATERIALS AND METHODS

This is a retrospective observational study. All clinical pregnancies achieved after in vitro fertilization or intracytoplasmic sperm injection treatment between January 1998 and April 2021 were analyzed. The primary outcome was miscarriage, defined as the pregnancy loss before 20 weeks of gestation age. Miscarriage rate was estimated per clinical pregnancy and gestational sac.

RESULTS

A total of 1222 clinical pregnancies from 1088 POSEIDON patients met the inclusion criteria. The miscarriage rates per clinical pregnancy in each POSEIDON subgroup were as follows: Group 1: 11.7 %, Group 2: 26.5 %, Group 3: 20.9 %, and Group 4: 37.5 %. The miscarriage rate per gestational sac showed a similar trend as the clinical miscarriage rate. Multivariate regression analysis showed that advanced maternal age is an independent factor for miscarriage (Group 2 vs. 1: OR 2.476; Group 4 vs. 3: OR 2.252). Patients with diminished ovarian reserve (DOR) have higher miscarriage risks but without significance (Group 3 vs. 1: OR 1.322; Group 4 vs. 2: OR 1.202).

CONCLUSION

Miscarriage rates differed among low prognosis patients according to the POSEIDON criteria. Age remains a determined risk for miscarriage. DOR might be a potential factor for miscarriage, but it didn't account for a significant impact in POSEIDON patients.

The effect of a vanishing twin on first- and second-trimester maternal serum markers and ultrasound screening for aneuploidy

A vanishing twin (VT) is the early demise of a twin fetus. It is estimated to occur in 20-30% of pregnancies associated with assisted reproductive technology. VT becomes increasingly prominent when assisted fertilization is used, because one or more embryos are transferred to the uterus. Maternal serum screening tests during pregnancy can screen for trisomy chromosomes 21, 18, and 13 and are divided into first- and second-trimester tests. In singleton pregnancies, the first trimester screening test is performed at 11-13 weeks and 6 days of gestation. It consists of two serum markers, pregnancy-associated plasma protein A and β-human chorionic gonadotropin (β-hCG), and measures nuchal translucency thickness. The second-trimester screening test was performed at 15-20 weeks and 6 days of gestation. It consists of four serum markers: alpha-fetoprotein, β-hCG, unconjugated estriol, and inhibin A. More effective screening for trisomy 21 in singleton pregnancies is achieved by analyzing cell-free DNA in the maternal blood. A VT includes a demise of the fetus. Although it affects maternal serum markers, it has not been corrected. Five studies examined the effect of VT on maternal serum markers, but the results were controversial. This study aimed to review the patterns of changes in maternal serum markers in VTs, interpret prenatal tests for pregnant women with VTs in clinical practice, and consider what information should be provided.

Fertility treatment increases the risk of preterm birth independent of multiple gestations

Objective

To investigate the complex interplay between fertility treatment, multiple gestations, and prematurity.

Design

Retrospective cohort study linking the national Center for Disease Control and Prevention infant birth and death data from 2014 to 2018.

Setting

National database from Center of Disease Control and Prevention.

Patients

In total, 19,454,155 live-born infants with gestational ages 22-44 weeks, 114,645 infants born using non IVF fertility treatment (NIFT), and 179,960 via assisted reproductive technology (ART).

Intervention

Noninvasive fertility treatment or ART vs. spontaneously conceived pregnancies.

Main Outcome Measures

The main outcome assessed was prematurity. Formal mediation analysis was conducted to calculate the percentage mediated by multiple gestations.

Results

Newborns born using NIFT or ART compared with those with no fertility treatment had a higher incidence of multiple gestation (no fertility treatment = 3.0%; NIFT = 24.7%; ART = 32.7%; P<.001) and prematurity (no fertility treatment = 11.2%; NIFT = 23.4%; ART = 28.4%; P<.001). Mediation analysis demonstrates that 76.8% (95% confidence interval [CI], 75.2%-78.1%) of the effect of NIFT on prematurity was mediated through multiple gestations. Similarly, 71.2% (95% CI, 70.8%-72.7%) of the effect of ART on prematurity is mediated through multiple gestation. However, the direct effect of NIFT on prematurity is 20.4% (95% CI, 19.0%-22.0%). The direct effect of ART was 24.7% (95% CI, 23.7%-25.6%).

Conclusion

A significant proportion of prematurity associated with fertility treatment is mediated by the treatment itself, independent of multiple gestations.

Nomogram for predicting the risk of preterm delivery after IVF/ICSI treatment: an analysis of 11513 singleton births

Background

There is a higher risk of preterm delivery (PTD) in singleton live births conceived after in vitro fertilization (IVF)/intracytoplasmic sperm injection (ICSI) compared with spontaneously conceived pregnancies. The objective of our study was to build a predictive nomogram model to suggest the possibility of PTD in singleton pregnancies after IVF/ICSI treatment.

Method

11513 IVF/ICSI cycles with singleton live births were enrolled retrospectively. These cycles were randomly allocated into a training group (80%) and a validation group (20%). We used the multivariate logistics regression analysis to determine prognostic factors for PTD in the training group. A nomogram based on the above factors was further established for predicting PTD. Receiver operating characteristic curves (ROC), areas under the ROC curves (AUC), concordance index (C-index), and calibration plots were analyzed for assessing the performance of this nomogram in the training and validation group.

Results

There were fourteen risk factors significantly related to PTD in IVF/ICSI singleton live births, including maternal body mass index (BMI) > 24 kg/m2, smoking, uterine factors, cervical factors, ovulatory factors, double embryo transferred (DET), blastocyst transfer, FET, vanishing twin syndrome (VTS), obstetric complications (placenta previa, placenta abruption, hypertensive of pregnancies, and premature rupture of membrane), and a male fetus. These factors were further incorporated to construct a nomogram prediction model. The AUC, C-index, and calibration curves indicated that this nomogram exhibited fair performance and good calibration.

Conclusions

We found that the occurrence of PTD increased when women with obesity, smoking, uterine factors, cervical factors, ovulatory factors, DET, VTS, and obstetric complications, and a male fetus. Furthermore, a nomogram was constructed based on the above factors and it might have great value for clinic use.

Promising Perinatal Outcome after Using a Simplified Low-Cost IVF Culture System Specifically Designed for Resource-Poor Countries

Background: Assisted reproductive techniques services are often not accessible to the majority of infertile couples in Low and Middle Income Countries (LMIC) due to high costs. Lowering IVF laboratory costs is a crucial step to make IVF affordable for a larger part of the world population. We developed a simplified culture system (SCS) which has proven to be effective, and the next step is to prove its safety.Methods: Preterm birth (PTB) and low birthweight (LBW) of 176 singletons born after using the SCS, 105 after fresh embryo transfer (fresh ET), and 71 after frozen embryo transfer (frozen ET) were compared with all IVF/ICSI singletons born in Belgium between 2013 and 2018. When comparing our 105 SCS babies born after fresh ET with all Belgian babies born after conventional IVF only, we also adjusted for 7 risk factors known to influence perinatal outcome, namelythe mother’s age, day of transfer, pituitary inhibition protocol, rank of cycles, number of oocytes retrieved, number of embryos transferred, and gender of the baby.Findings: Before adjustment, we found a significantly higher PTB (10.2% vs. 3.8%, OR 2.852, 95% CI [1.042–7.803], p-value 0.0413) and LBW (9.8% vs. 2.9%, OR 3.692, 95% CI [1.163–11.721], p-value 0.0267) in the conventional IVF group versus SCS after fresh ET. After adjusting for seven risk parameters, these differences remained significant (PTB: OR 2.627, 95% CI [1.013–6.816], p-value 0.0471) and LBW: OR 3.267, 95% CI [1.118–9.549], p-value 0.0305). PTB and LBW between both groups was not significantly different for singletons born after frozen ET. Interpretation: Taking into account the small series, PTB and LBW rates in SCS singletons in FRET cycles are very reassuring and significantly lower compared to babies born after conventional IVF in Belgium. Being aware of its effectiveness, our results offer a good perspective for SCS to become an important tool to implement low-cost IVF in LMIC.

Risk of Hypertensive Disorders in Pregnancy After Fresh and Frozen Embryo Transfer in Assisted Reproduction: A Population-Based Cohort Study With Within-Sibship Analysis

BACKGROUND

Frozen embryo transfer (frozen-ET) is increasingly common because of improved cryopreservation methods and elective freezing of all embryos. Frozen-ET is associated with higher risk of hypertensive disorders in pregnancy than both natural conception and fresh embryo transfer (fresh-ET), but whether this is attributable to parental factors or treatment is unknown.

METHODS

Using the Medical Birth Registries of Denmark (1994-2014), Norway, and Sweden (1988-2015), linked to data from national quality registries and databases on assisted reproduction, we designed a population-based cohort study with within-sibship comparison. We included 4 426 691 naturally conceived, 78 300 fresh-ET, and 18 037 frozen-ET singleton pregnancies, of which 33 209 sibships were conceived using different conception methods. Adjusted odds ratios (aOR) of hypertensive disorders in pregnancy for fresh-ET and frozen-ET versus natural conception with 95% CI were estimated using multilevel logistic regression, where random effects provided conventional population-level estimates and fixed effects gave within-sibship estimates. Main models included adjustment for birth year, maternal age, parity, and country.

RESULTS

Risk of hypertensive disorders in pregnancy was higher after frozen-ET compared to natural conception, both at population-level (7.4% versus 4.3%, aOR, 1.74 [95% CI, 1.61-1.89]) and within sibships (aOR, 2.02 [95% CI, 1.72-2.39]). For fresh-ET, risk was similar to natural conception, both at population-level (aOR, 1.02 [95% CI, 0.98-1.07]) and within sibships (aOR, 0.99 [95% CI, 0.89-1.09]).

CONCLUSIONS

Frozen-ET was associated with substantially higher risk of hypertensive disorders in pregnancy, even after accounting for shared parental factors within sibships.

Obstetric and Perinatal Outcomes of Singleton Births Following Single- vs Double-Embryo Transfer in Sweden

Importance

Pregnancies resulting from assisted reproductive technology are associated with an increased risk of adverse perinatal outcomes compared with those following natural conception. Previous studies have shown an association of pregnancies resulting from transfer of multiple embryos with these negative findings.

Objective

To determine the risk for adverse outcomes in singletons conceived through assisted reproduction using double-embryo transfer (DET) vs single-embryo transfer (SET).

Design, Setting, and Participants

This cohort study used data from women who achieved singleton deliveries after SET or DET in Sweden between 2007 and 2017 as recorded in the National Quality Registry for Assisted Reproduction. All embryo transfers, at cleavage or blastocyst stage, replaced in fresh or frozen treatment cycles were included. Data on obstetric and neonatal outcomes were retrieved by linkage to the National Medical Birth Register. Naturally conceived singletons were included as a reference group. Data were analyzed between September 2021 and August 2022.

Exposures

Double-embryo transfer leading to singleton birth.

Main Outcomes and Measures

Relative risk ratios or odds ratios (ORs) and absolute risk differences (ARDs) in percentage points with 95% CIs were calculated for obstetric and perinatal outcomes in singleton births conceived using DET vs SET.

Results

Among 1 115 863 singleton births, 30 713 singletons were born after SET and 5123 after DET. A higher risk of neonatal death was found in singletons after DET vs SET (OR, 2.67 [95% CI, 1.28-5.55]; ARD, 0.2 percentage points [95% CI, 0.0-0.4 percentage points]). In frozen embryo transfers, DET was associated with a higher risk of low birth weight (OR, 1.64 [95% CI, 1.19-2.25]; ARD, 2.0 percentage points [95% CI, 0.5-3.5 percentage points]). Among blastocyst transfers, DET was associated with very preterm birth (relative risk ratio, 2.64 [95% CI, 1.50-4.63]; ARD, 1.8 percentage points [95% CI, 0.3-3.4 percentage points]) and low birth weight (OR, 1.83 [95% CI, 1.29-2.60]; ARD, 3.2 percentage points [95% CI, 0.9-5.5 percentage points]).

Conclusions and Relevance

These results indicate a higher risk of adverse outcomes following DET, even when the result is a singleton birth, vs singletons born after SET. Adverse outcomes were mainly observed in singletons following DET using frozen embryos and blastocysts.

Perinatal outcome of babies born after using a simplified IVF culture system versus ICSI with sibling oocytes: a prospective cohort study

RESEARCH QUESTION

Is there a difference in perinatal outcome in the same patient cohort for babies conceived following randomization of sibling oocytes allocated to a simplified IVF culture system (SCS) or intracytoplasmic sperm injection (ICSI) followed by conventional culturing?

DESIGN

The study compared the perinatal outcomes of 367 babies born from 1 January 2013 until 31 December 2020 after using split SCS and ICSI insemination of sibling oocytes in a selected group of normo-responsive women, excluding cases of severe male infertility. Primary outcome measures were preterm birth (PTB; <37 weeks' gestation), low birthweight (LBW; <2.5 kg) and small for gestational age (SGA) as a primary outcome parameter while secondary outcome measures included mean birthweight, mean gestational age, extreme prematurity (<32 weeks), very low birthweight (<1.5 kg), perinatal mortality, multiple pregnancy and Caesarean section rate.

RESULTS

A total of 105 and 103 singleton babies were born after fresh embryo transfer (FRET) and 71 and 50 singletons after frozen embryo transfer (FET) in the SCS and ICSI groups, respectively. For babies born after FRET, the LBW rate was 2.9% (3/105) for SCS and 7.8% (8/103) for ICSI (P = 0.10). LBW occurred in 4.2% (3/71) and 0% (0/50) of babies born after the transfer of cryopreserved-thawed SCS and ICSI embryos, respectively (P = 0.14). The rate of PTB was 3.8% and 6.8% for SCS and ICSI in FRET cycles (P = 0.33), and 8.5% and 6.0% for SCS and ICSI in FET cycles (P = 0.62). One congenital malformation was found in the SCS FET group.

CONCLUSION

There was no difference in perinatal outcome for singleton and twin babies born after SCS and ICSI.

Vanishing twin syndrome is associated with first-trimester intrauterine hematoma in twin pregnancies after in vitro fertilization

RESEARCH QUESTION

Is there an association between intrauterine hematoma (IUH), vanishing twin syndrome (VTS), and subsequent complications in twin pregnancies after in vitro fertilization (IVF)? What are the risk factors for these complications?

DESIGN

Women who presented with two live gestational sacs following double embryo transfer were included. Patients with systematic diseases, artificial fetal reduction, and incomplete data were excluded. Further stratification of IUH pregnancies was performed according to IUH-related characteristics (i.e., volume, changing pattern, and relationship with fetal cardiac activities). The primary outcome was the incidence of VTS, while adverse outcomes in the surviving singleton and the gestational age of VTS were secondary outcomes.

RESULTS

The incidence of IUH was 13.8%. A total of 1,078 twin pregnancies including 539 IUH pregnancies and 539 non-IUH pregnancies were included. IUH pregnancy was associated with higher risks of VTS (26.9% vs. 18.7%, p = 0.001) as well as a higher incidence of preterm birth (p = 0.001, crude OR = 1.98, 95% CI 1.28-3.09, adjusted OR = 1.19, 95% CI 1.09-1.24), threatened abortion (p < 0.001, crude OR = 9.12, 95% CI 2.90-28.69, adjusted OR = 6.63, 95% CI 1.69-14.67), and postpartum hemorrhage (p = 0.024, crude OR = 3.13, 95% CI 1.09-8.99, adjusted OR = 1.16, 95% CI 1.08-1.32) in the surviving singleton. There was no significant difference in risks of other complications. The absence of fetal cardiac activities at the diagnosis of IUH predicted VTS (p < 0.001, crude OR 4.67, 95% CI 3.67-5.78, adjusted OR 3.33, 95% CI 1.56-5.14) and fetal loss at smaller gestational age (7.81 ± 2.10 vs. 11.39 ± 5.60 weeks, p < 0.001), while an IUH with an increasing volume did not increase the risk of VTS but might induce threatened abortion in the surviving fetus (p < 0.001, crude OR 1.84, 95% CI 1.32-2.55, adjusted OR 1.72, 95% CI 1.13-2.13).

CONCLUSIONS

IUH was a risk factor for VTS in twin pregnancies following double embryo transfer and elevated the risks of threatened abortion, preterm birth, and postpartum hemorrhage in the surviving singleton. The absence of fetal cardiac activities at the diagnosis of IUH elevated the risks of VTS, while an IUH with an increasing volume was associated with threatened abortion without elevating the risks of VTS. An IUH diagnosed before the presence of fetal cardiac activities also resulted in an earlier miscarriage. The study suggests that attention be paid to twin pregnancies with first-trimester IUH to prevent VTS and subsequent adverse perinatal outcomes.

HIGHLIGHTS

First-trimester intrauterine hematoma (IUH) following double embryo transfer is associated with a higher incidence of vanishing twin syndrome (VTS) and elevated subsequent risk of threatened abortion, preterm birth, and postpartum hemorrhage in the surviving singleton. Other perinatal outcomes were not associated with the diagnosis of first-trimester IUH. The absence of fetal cardiac activities at the diagnosis of IUH was of predictive value toward VTS, while an IUH with an increasing size was associated with threatened abortion without elevating the risk of VTS. Incomplete fetal cardiac activities and earlier detection of an IUH might also predict miscarriage at smaller gestational age.

Cerebral palsy in ART children has declined substantially over time: a Nordic study from the CoNARTaS group

STUDY QUESTION

Are the decreasing multiple birth rates after ART associated with a simultaneous drop in the incidence of cerebral palsy (CP) in ART children over time?

SUMMARY ANSWER

The relative odds of CP in ART children have declined in the Nordic countries over the past two decades concurrently with declining multiple birth rates.

WHAT IS KNOWN ALREADY

In the Nordic countries, the rate of twin pregnancies after ART has decreased from 30% in the early 1990s to 4-13% in 2014, following the implementation of elective single embryo transfer (SET). Consequently, preterm birth rates have declined substantially in ART pregnancies. However, whether the risk of CP, a known consequence of preterm birth, has decreased correspondingly is still unknown.

STUDY DESIGN, SIZE, DURATION

Retrospective register-based cohort study based on data on all singletons, twins, and higher-order multiples born in Denmark (birth year 1994-2010), Finland (1990-2010), and Sweden (1990-2014), corresponding to 111 844 ART children and 4 679 351 spontaneously conceived children.

PARTICIPANTS/MATERIAL, SETTING, METHODS

Data were obtained from a large Nordic cohort of children born after ART and spontaneous conception initiated by the Committee of Nordic ART and Safety-CoNARTaS. The CoNARTaS cohort was established by cross-linking national register data using the unique personal identification number, allocated to every citizen in the Nordic countries. Data from the National Medical Birth Registers, where information on maternal, obstetric, and perinatal outcomes is recorded, were cross-linked to data from the National ART- and Patients Registers to obtain information on fertility treatments and CP diagnoses. Relative risks of CP for ART compared to spontaneous conception were estimated as odds ratios from multivariate logistic regression analyses across all birth years, as well as for the following birth year categories: 1990-1993, 1994-1998, 1999-2002, 2003-2006, 2007-2010, and 2011-2014. Analyses were made for all children and for singletons and twins, separately.

MAIN RESULTS AND THE ROLE OF CHANCE

The main outcome measure was the relative odds of CP in different time periods for ART versus spontaneously conceived children. CP was diagnosed in 661 ART children and 16 478 spontaneously conceived children born between 1990 and 2014. In 1990-1993, the relative odds of CP were substantially higher in all ART children (adjusted odds ratio (aOR) 2.76 (95% CI 2.03-3.67)) compared with all spontaneously conceived children, while in 2011-2014, it was only moderately higher (aOR 1.39 (95% CI 1.01-1.87)). In singletons, the higher relative odds of CP in ART children diminished over time from 1990 to 1993 (aOR 2.02 (95% CI 1.22-3.14)) to 2003-2006 (aOR 1.18 (95% CI 0.91-1. 49)) and was not significantly increased for birth cohorts 2007-2010 and 2011-2014. For ART twins versus spontaneously conceived twins, the relative odds of CP was not statistically significantly increased throughout the study period.

LIMITATIONS, REASONS FOR CAUTION

The main limitation of the study was a shorter follow-up time and younger age at first CP diagnosis for ART children compared with spontaneously conceived children. However, analyses ensuring a minimum of bias from differences in age at CP diagnosis and follow-up time confirmed the results, hence, we do not consider this to cause substantial bias.

WIDER IMPLICATIONS OF THE FINDINGS

A SET policy in ART treatments has the potential to reduce the increased risk of cerebral palsy in the ART population due to lower rates of multiple deliveries. At a time with high survival rates of frozen/thawed embryos, this study provides a strong argument against the continued use of multiple embryo transfer in most ART settings. Larger cohort studies including also the number of gestational sacs in early pregnancy will be preferable to show an effect of vanishing twins on the risk of CP in the ART population.

STUDY FUNDING/COMPETING INTEREST(S)

The study was financed by grants from NordForsk (grant number 71450), Elsass Foundation (19-3-0444), the ALF-agreement (ALFGBG 70940), and The Research Fund of Rigshospitalet, Copenhagen University Hospital. There are no conflicts of interest to declare.

TRIAL REGISTRATION NUMBER

ISRCTN11780826.

Advanced trophectoderm quality increases the risk of a large for gestational age baby in single frozen-thawed blastocyst transfer cycles

STUDY QUESTION

Does trophectoderm (TE) quality affect birthweight after single frozen-thawed blastocyst transfer?

SUMMARY ANSWER

Transfer of single blastocyst with advanced TE quality was associated with higher birthweight and increased risk of a large for gestational age (LGA) baby.

WHAT IS KNOWN ALREADY

Transfer of blastocysts with advanced TE quality results in higher ongoing pregnancy rates and a lower miscarriage risk. However, data on the relationship between TE quality and birthweight are still lacking.

STUDY DESIGN, SIZE, DURATION

This retrospective cohort study at a tertiary-care academic medical center included 1548 singleton babies born from single frozen-thawed blastocyst transfer from January 2011 to June 2019.

PARTICIPANTS/MATERIALS, SETTING, METHODS

Babies were grouped into four groups according to embryo expansion (Stages 3, 4, 5 and 6), three groups according to inner cell mass (ICM) quality (A, B and C), and three groups according to TE quality (A, B and C). Main outcomes included absolute birthweight, Z-scores adjusted for gestational age and gender, and adverse neonatal outcomes. Multivariable linear and logistic regression analyses were performed to investigate the association of neonatal outcomes with expansion stage, ICM quality and TE quality.

MAIN RESULTS AND THE ROLE OF CHANCE

As TE quality decreased, birthweight (3468.10 ± 471.52, 3357.69 ± 522.06, and 3288.79 ± 501.90 for A, B and C, respectively, P = 0.002), Z-scores (0.59 ± 1.07, 0.42 ± 1.04, and 0.27 ± 1.06 for A, B and C, respectively, P = 0.002) and incidence of LGA (28.9%, 19.7% and 17.4% for A, B and C, respectively, P = 0.027) decreased correspondingly. After adjusting for confounders, compared with the Grade A group, blastocysts with TE Grade B (standardized coefficients (β): -127.97 g, 95% CI: -234.46 to -21.47, P = 0.019) and blastocysts with TE grade C (β: -200.27 g, 95% CI: -320.69 to -79.86, P = 0.001) resulted in offspring with lower birthweight. Blastocysts with TE grade C brought babies with lower Z-scores than TE Grade A (β: -0.35, 95% CI: -0.59 to -0.10, P = 0.005). Also, embryos with TE Grade B (adjusted odds ratio (aOR):0.91, 95% CI: 0.84 to 0.99, P = 0.033) and embryos with TE Grade C (aOR : 0.89, 95% CI: 0.81 to 0.98, P = 0.016) had lower chance of leading to a LGA baby than those with TE Grade A. No association between neonatal outcomes with embryo expansion stage and ICM was observed (all P > 0.05).

LIMITATIONS, REASONS FOR CAUTION

The retrospective design, lack of controlling for several unknown confounders, and inter-observer variation limited this study.

WIDER IMPLICATIONS OF THE FINDINGS

The study extends our knowledge of the down-stream effect of TE quality on newborn birthweight and the risk of LGA.

STUDY FUNDING/COMPETING INTEREST(S)

This study was funded by National Key R&D Program of China (2018YFC1003000), National Natural Science Foundation of China (81771533 to Y.P.K. and 31200825 to L.S.) and Innovative Research Team of High-level Local Universities in Shanghai (SSMU-ZLCX20180401), Shanghai Sailing Program(21YF1423200) and the Fundamental research program funding of Ninth People's Hospital affiliated to Shanghai Jiao Tong university School of Medicine (JYZZ117). The authors declare no conflict of interest in this present study.

TRIAL REGISTRATION NUMBER

N/A.

Separating parental and treatment contributions to perinatal health after fresh and frozen embryo transfer in assisted reproduction: A cohort study with within-sibship analysis

BACKGROUND

Compared to naturally conceived children, adverse perinatal outcomes are more common among children born after assisted reproductive technology with fresh embryo transfer (fresh-ET) or frozen embryo transfer (frozen-ET). However, most previous studies could not adequately control for family confounding factors such as subfertility. We compared birth size and duration of pregnancy among infants born after fresh-ET or frozen-ET versus natural conception, using a within-sibship design to account for confounding by maternal factors.

METHODS AND FINDINGS

This registry-based cohort study with nationwide data from Denmark (1994-2014), Norway (1988-2015), and Sweden (1988-2015) consisted of 4,510,790 live-born singletons, 4,414,703 from natural conception, 78,095 from fresh-ET, and 17,990 from frozen-ET. We identified 33,056 offspring sibling groups with the same mother, conceived by at least 2 different conception methods. Outcomes were mean birthweight, small and large for gestational age, mean gestational age, preterm (<37 weeks, versus ≥37), and very preterm birth (<32 weeks, versus ≥32). Singletons born after fresh-ET had lower mean birthweight (-51 g, 95% CI -58 to -45, p < 0.001) and increased odds of small for gestational age (odds ratio [OR] 1.20, 95% CI 1.08 to 1.34, p < 0.001), while those born after frozen-ET had higher mean birthweight (82 g, 95% CI 70 to 94, p < 0.001) and increased odds of large for gestational age (OR 1.84, 95% CI 1.56 to 2.17, p < 0.001), compared to naturally conceived siblings. Conventional population analyses gave similar results. Compared to naturally conceived siblings, mean gestational age was lower after fresh-ET (-1.0 days, 95% CI -1.2 to -0.8, p < 0.001), but not after frozen-ET (0.3 days, 95% CI 0.0 to 0.6, p = 0.028). There were increased odds of preterm birth after fresh-ET (OR 1.27, 95% CI 1.17 to 1.37, p < 0.001), and in most models after frozen-ET, versus naturally conceived siblings, with somewhat stronger associations in population analyses. For very preterm birth, population analyses showed increased odds for both fresh-ET (OR 2.03, 95% CI 1.90 to 2.12, p < 0.001) and frozen-ET (OR 1.66, 95% CI 1.42 to 1.94, p < 0.001) compared with natural conception, but results were notably attenuated within siblings (OR 1.18, 95% CI 1.0 to 1.41, p = 0.059, and OR 0.92, 95% CI 0.67 to 1.27, p = 0.6, for fresh-ET and frozen-ET, respectively). Sensitivity analyses in full siblings, in siblings born within 3-year interval, by birth order, and restricting to single embryo transfers and blastocyst transfers were consistent with the main analyses. Main limitations were high proportions of missing data on maternal body mass index and smoking.

CONCLUSIONS

We found that infants conceived by fresh-ET had lower birthweight and increased odds of small for gestational age, and those conceived by frozen-ET had higher birthweight and increased odds of large for gestational age. Conception by either fresh-ET or frozen-ET was associated with increased odds of preterm birth. That these findings were observed within siblings, as well as in conventional multivariable population analyses, reduces the likelihood that they are explained by confounding or selection bias.

TRIAL REGISTRATION

ClinicalTrials.gov ISRCTN11780826.

Birthweight and other perinatal outcomes of singletons conceived after assisted reproduction compared to natural conceived singletons in couples with unexplained subfertility: follow-up of two randomized clinical trials

STUDY QUESTION

Does assisted reproduction, such as ovarian stimulation and/or laboratory procedures, have impact on perinatal outcomes of singleton live births compared to natural conception in couples with unexplained subfertility?

SUMMARY ANSWER

Compared to natural conception, singletons born after intrauterine insemination with ovarian stimulation (IUI-OS) had a lower birthweight, while singletons born after IVF had comparable birthweights, in couples with unexplained subfertility.

WHAT IS KNOWN ALREADY

Singletons conceived by assisted reproduction have different perinatal outcomes such as low birthweight and a higher risk of premature birth than naturally conceived singletons. This might be due to the assisted reproduction, such as laboratory procedures or the ovarian stimulation, or to an intrinsic factor in couples with subfertility.

STUDY DESIGN, SIZE, DURATION

We performed a prospective cohort study using the follow-up data of two randomized clinical trials performed in couples with unexplained subfertility. We evaluated perinatal outcomes of 472 live birth singletons conceived after assisted reproduction or after natural conception within the time horizon of the studies.

PARTICIPANTS/MATERIALS, SETTING, METHODS

To assess the possible impact of ovarian stimulation we compared the singletons conceived after IUI with FSH or clomiphene citrate (CC) and IVF in a modified natural cycle (IVF-MNC) or standard IVF with single embryo transfer (IVF-SET) to naturally conceived singletons in the same cohorts. To further look into the possible effect of the laboratory procedures, we put both IUI and IVF groups together into IUI-OS and IVF and compared both to singletons born after natural conception. We only included singletons conceived after fresh embryo transfers. The main outcome was birthweight presented as absolute weight in grams and gestational age- and gender-adjusted percentiles. We calculated differences in birthweight using regression analyses adjusted for maternal age, BMI, smoking, parity, duration of subfertility and child gender.

MAIN RESULTS AND THE ROLE OF CHANCE

In total, there were 472 live birth singletons. Of the 472 singleton pregnancies, 209 were conceived after IUI-OS (136 with FSH and 73 with CC as ovarian stimulation), 138 after IVF (50 after IVF-MNC and 88 after IVF-SET) and 125 were conceived naturally.Singletons conceived following IUI-FSH and IUI-CC both had lower birthweights compared to naturally conceived singletons (adjusted difference IUI-FSH -156.3 g, 95% CI -287.9 to -24.7; IUI-CC -160.3 g, 95% CI -316.7 to -3.8). When we compared IVF-MNC and IVF-SET to naturally conceived singletons, no significant difference was found (adjusted difference IVF-MNC 75.8 g, 95% CI -102.0 to 253.7; IVF-SET -10.6 g, 95% CI -159.2 to 138.1). The mean birthweight percentile was only significantly lower in the IUI-FSH group (-7.0 percentile, 95% CI -13.9 to -0.2). The IUI-CC and IVF-SET group had a lower mean percentile and the IVF-MNC group a higher mean percentile, but these groups were not significant different compared to the naturally conceived group (IUI-CC -5.1 percentile, 95% CI -13.3 to 3.0; IVF-MNC 4.4 percentile, 95% CI -4.9 to 13.6; IVF-SET -1.3 percentile, 95% CI -9.1 to 6.4).Looking at the laboratory process that took place, singletons conceived following IUI-OS had lower birthweights than naturally conceived singletons (adjusted difference -157.7 g, 95% CI -277.4 to -38.0). The IVF group had comparable birthweights with the naturally conceived group (adjusted difference 20.9 g, 95% CI -110.8 to 152.6). The mean birthweight percentile was significantly lower in the IUI-OS group compared to the natural group (-6.4 percentile, 95% CI -12.6 to -0.1). The IVF group was comparable (0.7 percentile, 95% CI -6.1 to 7.6).

LIMITATIONS, REASONS FOR CAUTION

The results are limited by the number of cases. The data were collected prospectively alongside the randomized controlled trials, but analyzed as treated.

WIDER IMPLICATIONS OF THE FINDINGS

Our data suggest IUI in a stimulated cycle may have a negative impact on the birthweight of the child and possibly on pre-eclampsia. Further research should look into the effect of different methods of ovarian stimulation on placenta pathology and pre-eclampsia in couples with unexplained subfertility using naturally conceived singletons in the unexplained population as a reference.

STUDY FUNDING/COMPETING INTEREST(S)

Both initial trials were supported by a grant from ZonMW, the Dutch Organization for Health Research and Development (INeS 120620027, SUPER 80-83600-98-10192). The INeS study also had a grant from Zorgverzekeraars Nederland, the Dutch association of healthcare insurers (09-003). B.W.J.M. is supported by an NHMRC investigator Grant (GNT1176437) and reports consultancy for ObsEva, Merck Merck KGaA, Guerbet and iGenomix, outside the submitted work. A.H. reports grants from Ferring Pharmaceutical company (the Netherlands), outside the submitted work. F.J.M.B. receives monetary compensation as a member of the external advisory board for Merck Serono (the Netherlands), Ferring Pharmaceutics BV (the Netherlands) and Gedeon Richter (Belgium), he receives personal fees from educational activities for Ferring BV (the Netherlands) and for advisory and consultancy work for Roche and he receives research support grants from Merck Serono and Ferring Pharmaceutics BV, outside the submitted work. The remaining authors have nothing to disclose.

TRIAL REGISTRATION NUMBER

INeS study Trial NL915 (NTR939); SUPER Trial NL3895 (NTR4057).

Further evidence that a supraphysiologic estradiol level during ovarian stimulation affects birthweight: findings of fresh and frozen embryo transfer with comparable estradiol levels on human chorionic gonadotropin trigger

Studies have reported a supraphysiologic estradiol (E2) level during ovarian stimulation may be related to low birthweight after fresh embryo transfer (ET), but whether a high E2 level in the stimulation cycle affects birthweight via frozen ET remained controversial. The study was to investigate whether a supraphysiologic E2 level in ovarian stimulation cycle affects birth weight in infants conceived via subsequent FET. In this retrospective cohort study, 2525 singletons conceived via FET and 2668 singletons conceived via fresh ET were analyzed. The birthweight and incidences of small for gestational age (SGA) in infants conceived via FET in groups with low and high levels of E2 did not differ significantly. Multivariate analyses showed that the peak E2 level was not predictive of SGA in infants conceived via FET. Singletons conceived via fresh ET had a higher risk of SGA than those conceived via FET even after comparable previous exposure to a high level of E2 > 3000 pg/mL. Our study results indicated that the increased risk of SGA was at least partly a result of the supraphysiologic E2 exposure to the intrauterine environment.

The late vanishing of a co-twin contributes to adverse perinatal outcomes in the surviving singleton

STUDY QUESTION

Is the vanishing of a co-twin after or before the ultrasonic registration of cardiac activity at approximately 6-8 weeks of gestation associated with adverse perinatal outcomes?

SUMMARY ANSWER

The timing of the demise of a co-twin after the registration of cardiac activity is an independent risk factor for adverse perinatal outcomes.

WHAT IS KNOWN ALREADY

A significant body of evidence has confirmed that vanishing twin (VT) pregnancies are associated with higher levels of risk for preterm birth (PTB), low birthweight (LBW), small-for-gestational age (SGA) and perinatal mortality, compared with singleton pregnancy. However, the impact of co-twin vanishing, before or after the presence, of cardiac activity, on perinatal outcomes has yet to be extensively investigated.

STUDY DESIGN, SIZE, DURATION

We retrospectively reviewed the medical records of 38 876 singletons delivered from ART cycles between 2006 and 2018, at the Peking University Third Hospital.

PARTICIPANTS/MATERIALS, SETTING, METHODS

In total, 35 188 singletons were delivered from the singleton pregnancy group, 2256 singletons from the VT pregnancy group after that cardiac activity was noted, and 1432 singletons were delivered from the VT pregnancy group before cardiac activity could be registered. Using the Poisson model, the adjusted risk ratio (aRR) was used to estimate the incidence of PTB, LBW, SGA and perinatal mortality, in the pregnancies of two types of VT compared with singleton pregnancies after correction for potential confounding factors.

MAIN RESULTS AND THE ROLE OF CHANCE

The vanishing of a co-twin after the registration of cardiac activity was associated with an increased risk of perinatal mortality when compared with the group of singleton pregnancies (0.5% vs 0.2%; P = 0.006); this association still existed after adjustment for potential confounders (aRR 2.19, 95% CI 1.12-4.30; P = 0.023). Furthermore, it was significantly associated with a higher risk of PTB (all cycles aRR 2.00, 95% CI 1.77-2.24; P < 0.001; fresh transfer aRR 2.06, 95% CI 1.78-2.38; P < 0.001; frozen transfer aRR 1.87, 95% CI 1.52-2.28; P < 0.001), LBW (all cycles aRR 2.47, 95% CI 2.12-2.88; P < 0.001; fresh transfer aRR 2.50, 95% CI 2.07-3.02; P < 0.001; frozen transfer aRR 2.39; 95% CI 1.83-3.12; P < 0.001) and SGA (all cycles aRR 1.56, 95% CI 1.35-1.80; P < 0.001; fresh transfer aRR 1.53, 95% CI 1.29-1.81; P < 0.001; frozen transfer aRR 1.62, 95% CI 1.24-2.11; P < 0.001). However, prior to the presence of cardiac activity, the vanishing of a co-twin was not associated with a higher risk of perinatal mortality (all cycles aRR 0.71, 95% CI 0.17-2.92; P = 0.636; fresh cycles aRR 0.51, 95% CI 0.07-3.70; P = 0.502; frozen cycles aRR 1.29, 95% CI 0.17-9.66; P = 0.803), PTB (all cycles aRR 1.11, 95% CI 0.91-1.34; P = 0.301; fresh cycles aRR 1.10, 95% CI 0.87-1.39; P = 0.447; frozen cycles aRR 1.13, 95% CI 0.81-1.58; P = 0.467), LBW (all cycles aRR 1.19, 95% CI 0.91-1.55; P = 0.207; fresh cycles aRR 1.08, 95% CI 0.77-1.51; P = 0.668; frozen cycles aRR 1.45, 95% CI 0.93-2.25; P = 0.100) and SGA (all cycles aRR 1.09, 95% CI 0.89-1.35; P = 0.405; fresh cycles aRR 0.97, 95% CI 0.75-1.26; P = 0.839). Pregnancies involving the two types of VT were significantly different in terms of PTB (all cycles aRR 1.80, 95% CI 1.45-2.24; P < 0.001; fresh cycles aRR 1.88, 95% CI 1.44-2.45; P < 0.001; frozen cycles aRR 1.65, 95% CI 1.13-2.40; P = 0.009), LBW (all cycles aRR 2.08, 95% CI 1.55-2.79; P < 0.001; fresh cycles aRR 2.32, 95% CI 1.61-3.36; P < 0.001; frozen cycles aRR 1.65, 95% CI 1.01-2.70; P = 0.046) and SGA (all cycles aRR 1.70, 95% CI 1.36-2.11; P < 0.001; fresh cycles aRR 1.87, 95% CI 1.42-2.45; P < 0.001).

LIMITATIONS, REASONS FOR CAUTION

The present data are not able to differentiate between co-twin demise occurring in the first or second trimester. Because the second trimester ultrasound scan is not an integral aspect of IVF assessment, this information was not available in the database.

WIDER IMPLICATIONS OF THE FINDINGS

Adverse perinatal outcomes in ART babies can be avoided by replacing one embryo at a time. It is possible to apply selective single embryo transfer strategy for all while maintaining acceptable success rates.

STUDY FUNDING/COMPETING INTEREST(S)

This study was supported by the National Natural Science Foundation of China for Young Scholars (Reference number: 31801251). No competing interests to declare.

TRIAL REGISTRATION NUMBER

not applicable.

Association between peak serum estradiol level during controlled ovarian stimulation and neonatal birthweight in freeze-all cycles: a retrospective study of 8501 singleton live births

STUDY QUESTION

Is there an association between peak serum estradiol (E2) level during controlled ovarian stimulation (COS) and neonatal birthweight in freeze-all cycles?

SUMMARY ANSWER

Peak serum E2 level during ovarian stimulation is not associated with neonatal birthweight in freeze-all cycles.

WHAT IS KNOWN ALREADY

Supraphysiologic E2 levels during COS have been demonstrated to generate a suboptimal peri-implantation endometrial environment and thus lead to adverse neonatal outcomes in fresh embryo transfer cycles. Previous experimental studies also suggested a potential influence of superovulation on oocyte epigenetic programming, but whether it translates into altered phenotypes of fetal growth and development remains unclear in clinical practice. By segmenting the process of COS and embryo transfer, the freeze-all policy provides a novel model to investigate the sole impact of ovarian stimulation on oocytes after ruling out the effects of hyperestrogenic milieu on endometrium in fresh cycles.

STUDY DESIGN, SIZE, DURATION

A retrospective cohort study of 8501 patients who underwent their first COS cycles with a freeze-all strategy and delivered live-born singletons in subsequent frozen-thawed embryo transfer cycles from January 2007 to December 2016 at a tertiary-care academic medical center.

PARTICIPANTS/MATERIALS, SETTING, METHODS

Patients were categorized into six groups according to E2 level on trigger day in regular increments of 1000 pg/mL: <1000, 1000-1999, 2000-2999, 3000-3999, 4000-4999 and ≥5000 pg/mL. Univariable and multivariable linear regression and logistic regression analysis were performed to assess the independent association between peak E2 level and measures of neonatal birthweight including absolute birthweight, Z-score, low birthweight (LBW) and small-for-gestational age (SGA).

MAIN RESULTS AND THE ROLE OF CHANCE

The six groups did not differ significantly in birthweight, Z-score or the incidence of LBW and SGA. Compared with the E2 <1000 pg/mL group, the adjusted mean difference (95% confidence interval [CI]) of stratified higher E2 groups was 17.2 (-31.0-65.5), 12.3 (-35.9-60.5), -4.1 (-51.9-43.7), -0.6 (-48.9-47.8) and -3.6 (-50.0-42.8) g for birthweight, and 0 (-0.11-0.10), 0.02 (-0.08-0.12), 0.04 (-0.06-0.14), -0.01 (-0.11-0.10) and -0.04 (-0.14-0.06) for Z-score, respectively. Regarding the outcomes of LBW and SGA, no increased risks were observed in each E2 category, with the adjusted odds ratio (95% CI) being 1.21 (0.68-2.16), 1.0 (0.58-1.90), 0.90 (0.50-1.63), 0.93 (0.51-1.69) and 1.08 (0.61-1.90) for LBW, and 0.97 (0.58-1.64), 1.06 (0.63-1.77), 0.77 (0.46-1.31), 0.71 (0.41-1.22) and 1.00 (0.60-1.65) for SGA, respectively.

LIMITATIONS, REASONS FOR CAUTION

The study was retrospective in design, and other unknown confounding factors may not be included for adjustment. Furthermore, the generalization of the study finding could be limited to some extent by the majority of double cleavage-stage embryo transfer and difference in birthweight reference percentiles between Chinese and other populations.

WIDER IMPLICATIONS OF THE FINDINGS

Our observations suggest that the hyperestrogenic milieu during COS does not seem to pose adverse effects on neonatal birthweight after frozen-thawed embryo transfer, which provides reassuring information for high ovarian responders in freeze-all cycles concerning their offspring's health.

STUDY FUNDING/COMPETING INTEREST(S)

This study was funded by the National Key Research and Development Program of China (SQ2018YFC100163) and National Natural Science Foundation of China (81571397, 81771533). The authors declare no conflict of interest.

Risks of nonchromosomal birth defects, small-for-gestational age birthweight, and prematurity with in vitro fertilization: effect of number of embryos transferred and plurality at conception versus at birth

PURPOSE

Excess embryos transferred (ET) (> plurality at birth) and fetal heartbeats (FHB) at 6 weeks' gestation are associated with reductions in birthweight and gestation, but prior studies have been limited by small sample sizes and limited IVF data. This analysis evaluated associations between excess ET, excess FHB, and adverse perinatal outcomes, including the risk of nonchromosomal birth defects.

METHODS

Live births conceived via IVF from Massachusetts, New York, North Carolina, and Texas included 138,435 children born 2004-2013 (Texas), 2004-2016 (Massachusetts and North Carolina), and 2004-2017 (New York) were classified by ET and FHB. Major birth defects were reported by statewide registries within the first year of life. Logistic regression was used to estimate adjusted odds ratios (AORs) and 95% CIs of the risks of a major nonchromosomal birth defect, small-for-gestational age birthweight (SGA), low birthweight (LBW), and preterm birth (≤36 weeks), by excess ET, and excess ET + excess FHB, by plurality at birth (singletons and twins).

RESULTS

In singletons with [2 ET, FHB =1] and [≥3 ET, FHB=1], risks [AOR (95% CI)] were increased, respectively, for major nonchromosomal birth defects [1.13 (1.00-1.27) and 1.18 (1.00-1.38)], SGA [1.10 (1.03-1.17) and 1.15 (1.05-1.26)], LBW [1.09 (1.02-1.13) and 1.17 (1.07-1.27)], and preterm birth [1.06 (1.00-1.12) and 1.14 (1.06-1.23)]. With excess ET + excess FHB, risks of all adverse outcomes except major nonchromosomal birth defects increased further for both singletons and twins.

CONCLUSION

Excess embryos transferred are associated with increased risks for nonchromosomal birth defects, reduced birthweight, and prematurity in IVF-conceived births.

Association between serum oestradiol level on the hCG administration day and neonatal birthweight after IVF-ET among 3659 singleton live births

Oestradiol, an important hormone in follicular development and endometrial receptivity, is closely related to clinical outcomes of fresh in vitro fertilization-embryo transfer (IVF-ET) cycles. A supraphysiologic E2 level is inevitable during controlled ovarian hyper-stimulation (COH), and its effect on the outcome of IVF-ET is controversial. The aim of this retrospective study is to evaluate the association between elevated serum oestradiol (E2) levels on the day of human chorionic gonadotrophin (hCG) administration and neonatal birthweight after IVF-ET cycles. The data of 3659 infertile patients with fresh IVF-ET cycles were analysed retrospectively between August 2009 and February 2017 in First Hospital of Zhengzhou University. Patients were categorized by serum E2 levels on the day of hCG administration into six groups: group 1 (serum E₂ levels ≤ 1000 pg/mL, n = 230), group 2 (serum E2 levels between 1001 and 2000 pg/mL, n = 524), group 3 (serum E₂ levels between 2001 and 3000 pg/mL, n = 783), group 4 (serum E₂ levels between 3001 and 4000 pg/mL, n = 721), group 5 (serum E2 levels between 4001 and 5000 pg/mL, n = 548 ), and group 6 (serum E2 levels > 5000 pg/mL, n = 852). Univariate linear regression was used to evaluate the independent correlation between each factor and outcome index. Multiple logistic regression was used to adjust for confounding factors. The LBW rates were as follows: 3.0% (group 1), 2.9% (group 2), 1.9% (group 3), 2.9% (group 4), 2.9% (group 5), and 2.0% (group 6) (P = 0.629), respectively. There were no statistically significant differences in the incidences of neonatal LBW among the six groups. We did not detect an association between peak serum E2 level during ovarian stimulation and neonatal birthweight after IVF-ET. The results of this retrospective cohort study showed that serum E2 peak levels during ovarian stimulation were not associated with birth weight during IVF cycles. In addition, no association was found between higher E2 levels and increased LBW risk. Our observations suggest that the hyper-oestrogenic milieu during COS does not seem to have adverse effects on the birthweight of offspring after IVF. Although this study provides some reference, the obstetric-related factors were not included due to historical reasons. The impact of the high estrogen environment during COS on the birth weight of IVF offspring still needs future research.

Decreased Endometrial Thickness Is Associated With Higher Risk of Neonatal Complications in Women With Polycystic Ovary Syndrome

PURPOSE

To evaluate the association of endometrial thickness (EMT) with obstetric and neonatal outcomes in women with polycystic ovary syndrome (PCOS).

METHODS

A total of 1755 subfertile PCOS women with singleton livebirths after frozen-thawed embryo transfer were included between January 2009 and September 2019. Main obstetric outcomes were hypertensive disorders in pregnancy and abnormal placentation. Main neonatal outcomes were preterm birth (PTB), low birthweight (LBW) and small-for-gestational age (SGA). Crude and adjusted odds ratios (ORs) with 95% confidence intervals (CIs) were estimated by univariate and multivariate logistic regression analyses.

RESULTS

Each millimeter decrease in EMT was related to a 9% (adjusted OR 1.09, 95% CI 1.00-1.19; P = 0.053), 14% (adjusted OR 1.14, 95% CI 1.02-1.28; P = 0.002) and 22% (adjusted OR 1.22, 95% CI 1.07-1.38; P = 0.003) higher risk of PTB, LBW and SGA, respectively. Compared to women with EMT >13 mm, women with EMT ≤8 mm also had significantly higher risk of PTB (adjusted OR 3.79, 95% CI 1.53-9.39; P = 0.004), LBW (adjusted OR 4.33, 95% CI 1.39-13.50; P = 0.012) and SGA (adjusted OR 6.38, 95% CI 1.78-22.83; P = 0.004). These associations remained consistent in further subgroup analysis by endometrial preparation regimen and in sensitivity analyses among nulligravida women or women without adverse obstetric outcomes. No significant differences were found in the incidence of several pregnancy complications across EMT categories.

CONCLUSION

Decreased EMT was independently associated with increased risk of PTB, LBW and SGA in women with PCOS.

Perinatal outcomes in vanishing twin pregnancies following assisted reproductive technology (ART) - a systematic review and meta-analysis

Objectives To compare the fetal and maternal outcomes in surviving singletons of vanishing twin, with singletons or twins, in pregnancies following assisted reproductive technology (ART). Content We searched the PubMed, Embase, Web of Science and Cochrane databases from the time of conception of the database until Dec 2019 to identify relevant published studies. Perinatal outcomes were synthesized with random effects meta-analysis using RevMan 5.3. Summary and Outlook Fifteen studies were included. Dichorionic twin pregnancies conceived by ART wherein the vanishing twin phenomenon occurred had a risk of fetal malformation similar to that of ART singleton pregnancies (OR=1.25; 95% CI 0.87-1.79) and a higher risk of fetal malformation compared with ART twin pregnancies (OR=1.82; 95% CI 1.23-2.70). Moreover, the remaining fetus in ART vanishing twin pregnancy was at a significantly higher risk of preterm birth (<37 weeks) compared to fetuses in ART singleton pregnancies (OR=2.41; 95% CI 1.46-3.99) and a markedly lower risk of preterm birth (<37 weeks) compared to the fetuses in ART twin pregnancies (OR=0.19; 95% CI 0.16-0.22). Meanwhile, the risk of delivery of infants who were small for gestational age (SGA) was significantly higher in ART vanishing twin pregnancies compared to that in ART singleton pregnancies (OR=2.70; 95% CI 1.39-5.24) and similar to that in ART twin pregnancies (OR=0.67; 95% CI 0.27-1.65). The risks of preterm birth and of the infant being SGA is higher for the remaining fetus in an ART vanishing twin pregnancy compared to those for the fetuses in ART singleton pregnancies; the risk of fetal malformation is also higher in such cases compared with ART twin pregnancies.

Is vanishing twin syndrome associated with adverse obstetric outcomes of ART singletons? A systematic review and meta-analysis

PURPOSE

The objective of our meta-analysis was to estimate the effect of VTS on obstetric outcomes of ART singletons.

METHODS

PubMed, Embase, MEDLINE, and ClinicalTrials.gov were searched up to January 2019 to find studies reporting the obstetric outcomes of ART singletons with VTS. Dichotomous data were expressed as odds ratios (OR) with 95% confidence intervals (CI). Continuous data were expressed as weighted mean difference (WMD) with 95% CI.

RESULTS

A total of 17 observational studies encompassing more than 60,000 ART singletons were included in this meta-analysis. The impact of VTS on singletons was highly dependent on the definition of VTS, precisely, the vanishing timing and intrauterine growth stage. When VTS happened at or before 14 weeks, regardless of intrauterine growth stage, there were no differences in terms of gestational age (GA) [WMD = - 0.08, 95% CI = - 0.27, 0.10], preterm birth (< 37 weeks) (PTB) [OR = 1.23, 95% CI = 0.89, 1.70], and low birth weight (< 2.5 kg) (LBW) [OR = 1.56, 95% CI = 1.00, 2.43] in original singletons versus singleton with VTS. On the contrary, VTS occurred after 14 weeks was associated with significantly shorter GW and lower BW, as well as higher risks of PTB and LBW. When the sac reduced in VTS was an empty gestational sac, there would be no differences in GW, PTB, and LBW between singletons versus singletons with VTS, whereas the loss of a fetus with cardiac-activity was associated with adverse obstetric outcomes.

CONCLUSIONS

This meta-analysis suggests whether or not VTS is harmful to obstetric outcomes is highly dependent on the vanishing timing and intrauterine growth stage.

Obstetric and neonatal outcomes after the transfer of vitrified-warmed blastocysts developing from nonpronuclear and monopronuclear zygotes: a retrospective cohort study

OBJECTIVE

To evaluate the obstetric and neonatal outcomes after the transfer of vitrified-warmed single blastocysts developing from nonpronuclear (0PN) and monopronuclear (1PN) zygotes.

DESIGN

Cohort study.

SETTING

Affiliated hospital.

PATIENT(S)

This study was a retrospective analysis of 435 0PN and 281 1PN vitrified-warmed single blastocyst transfers, and 151 0PN and 75 1PN singletons, compared with 13,167 two-pronuclear (2PN) vitrified-warmed single blastocyst transfers and 4,559 2PN singletons, respectively.

INTERVENTION(S)

None.

MAIN OUTCOME MEASURE(S)

Pregnancy rate (PR), abortion rate (AR), live birth rate (LBR), and singleton birthweight were the primary outcome measures.

RESULT(S)

PR, AR, and LBR were similar when compared between the 0PN and 2PN groups after vitrified-warmed blastocyst transfer. However, the 0PN group had a higher birthweights, higher z scores, and a greater proportion of very large for gestational age newborns. When comparing the 1PN and 2PN groups, we found that the PR was similar whereas the AR was higher and the LBR was lower. No differences were detected in the other neonatal outcomes.

CONCLUSION(S)

The results of the present study show that the transfer of 2PN blastocysts should be prioritized because of a higher AR and a lower LBR after 1PN blastocyst transfers and a higher birthweight after 0PN blastocyst transfers when compared with 2PN blastocyst transfers. Our data indicate the need for concern about the safety of 1PN and 0PN embryo transfers.

Comparison of the rates of preterm birth and low birth weight of vanishing twin and primary pregnancies conceived with assisted reproductive technology

OBJECTIVES

The purpose of this study was to compare the rate of preterm birth, low birth weight, and foetal growth restriction in assisted reproductive technology (ART) singleton pregnancies diagnosed with vanishing twin (VT) syndrome to those of ART pregnancies that were originally singleton pregnancies.

METHODS

In this retrospective study, 177 pregnancies diagnosed with VT syndrome were matched and compared with 218 primary singleton pregnancies. The preterm birth and low birth weight rates of these two groups were evaluated. All pregnancies were conceived through ART and delivered at Peking University First Hospital and Hebei Xingtai Infertility Hospital from 2014 to 2016.

RESULTS

The preterm delivery rate (20.90 vs. 8.72%, p<0.05) was significantly higher in the ART singletons with VT syndrome than in the control singleton group. The proportion of low-birth-weight (<2500 g) infants was also higher in the VT group than in the primary singleton group (10.73 vs. 3.67%, p<0.05). In addition, the preterm birth rate of the naturally conceived singletons was significantly lower than that of the ART singletons (6.00 vs. 14.18%, p<0.05).

CONCLUSIONS

ART singleton pregnancies with VT syndrome have higher rates of preterm birth and low-birth-weight new-borns than ART pregnancies that were originally singleton pregnancies.

Number of embryos transferred and diagnosis of preeclampsia

BACKGROUND

Multiple births and first pregnancy are associated with higher preeclampsia risk. It is unknown if the transfer of multiple embryos or first embryo transfer with assisted reproductive technology (ART) is also associated with greater preeclampsia risk.

METHODS

We performed a retrospective cohort study of IVF clinics and hospitals in Massachusetts. We used linked ART surveillance, birth certificate, and maternal hospitalization discharge data for 21,188 births, considering resident singleton (12,810) and twin (8378) live-births from autologous or donor eggs from 2005 to 2012. We used log binomial and Poisson regression to calculate adjusted relative risks (aRRs) and 95% confidence intervals (CI) for the association between preeclampsia and predictors of preeclampsia. Outcomes were stratified by singleton and twin birth, donor versus autologous cycles, and use of fresh versus cryopreserved embryos.

RESULTS

Considering all singleton births, the transfer of multiple embryos increased the risk of preeclampsia [aRR = 1.10 (95% CI: 1.01-1.19)]. Relative risks were greatest for fresh non-donor cycles [aRR = 1.14 (95% CI: 1.03-1.26)]. Vanishing twin and number of prior ART cycles was not associated with preeclampsia among singleton births [aRR = 1.18 (95% CI: 0.91-1.53)], and aRR = 1.01 (95% CI: 0.96-1.05)], respectively. Considering all twin births, the transfer of > 2 embryos increased the risk of preeclampsia [aRR = 1.09 (95% CI: 1.001-1.19)]. Vanishing triplet and number of prior ART cycles were not associated with preeclampsia among twin births [aRR = 0.93 (95% CI: 0.69-1264), and aRR = 0.98 (CI: 0.95-1.02)], respectively.

CONCLUSIONS

Among ART births, the transfer of more than 1 embryo for singleton gestations and more than 2 embryos for twin gestations increased the risk for preeclampsia diagnosis.

Association between endometrial thickness and neonatal outcomes in intrauterine insemination cycles: a retrospective analysis of 1,016 live-born singletons

BACKGROUND

Decreased endometrial thickness (EMT) has been suggested to be associated with reduced birthweight of in vitro fertilization/intracytoplasmic sperm injection (IVF/ICSI) newborns. Considering the differences in ovarian stimulation degree and laboratory procedures between IVF/ICSI and IUI treatment, we aim to investigate whether EMT has any influence on IUI infant outcomes as well.

METHODS

This was a retrospective cohort study of 1016 patients who had singleton livebirths after IUI treatment cycles from January 2008 to December 2018 at a tertiary-care academic medical center in China. Patients were categorized into three groups by the 10th and 90th percentile of peak EMT: ≤7.6, 7.7-13.0 and ≥ 13.1 mm. The primary outcomes of the study were preterm birth (PTB), low birthweight (LBW) and small-for-gestational age (SGA). Multiple regression analyses were performed after controlling for a variety of potential confounders.

RESULTS

No significant differences were found among the three groups in gestational age, birthweight and birthweight Z-score. Compared with the EMT 7.7-13.0 mm group, the incidences of PTB, LBW and SGA were 5.5% (adjusted odds ratio [aOR] 0.81, 95% confidence interval [CI] 0.33-2.01), 6.4% (aOR 1.44, 95% CI 0.58-3.58) and 7.3% (aOR 1.21, 95% CI 0.53-2.76) in the EMT ≤7.6 mm group, respectively. Similarly, EMT ≥13.1 mm was not significantly associated with risks of PTB (aOR 0.63, 95% CI 0.24-1.65), LBW (aOR 0.57, 95% CI 0.17-1.95) and SGA (aOR 0.73, 95% CI 0.28-1.92). The odds of other adverse neonatal outcomes, including macrosomia, large-for-gestational age and major congenital malformations, did not show significant differences before and after adjustment in both EMT ≤7.6 and ≥ 13.1 mm groups.

CONCLUSIONS

EMT is not independently associated with adverse perinatal outcomes in IUI cycles. This novel finding would provide reassuring information for IUI patients with thin endometrial linings regarding their neonatal health. However, further prospective cohort studies with larger datasets are needed to confirm the conclusion.

The impact of selected embryo culture conditions on ART treatment cycle outcomes: a UK national study

STUDY QUESTION

Are selected embryo culture conditions namely media, oxygen level, and incubator type, associated with IVF live birth rate (LBR) and the health of singleton offspring at birth?

SUMMARY ANSWER

There were statistically significant differences in LBR between the eight culture media systems analysed; however, none of the embryo culture factors showed statistically significant associations with birth weight (BW) in multivariable regression analyses.

WHAT IS KNOWN ALREADY

In clinical ART culture media is the initial environment provided for the growth of human embryos. Pre-implantation development is a critical period of developmental plasticity, which could have long-lasting effects on offspring growth and health. Although some studies have shown an impact of culture medium type on BW, the interaction between culture medium type and associated culture conditions on both treatment success rates (LBR) and offspring BW is largely unexplored. This study aimed to examine these factors in a large multicentre national survey capturing the range of clinical practice.

STUDY DESIGN, SIZE, DURATION

In this cross-sectional study, data from a survey circulated to all UK IVF clinics requesting information regarding culture medium type, incubator type, and oxygen level used in ART between January 2011 and December 2013 were merged with routinely recorded treatment and outcome data held in the Human Fertilisation and Embryology Authority Register up to the end of 2014.

PARTICIPANTS/MATERIALS, SETTING, METHODS

Forty-six (62%) UK clinics responded to the survey. A total of 75 287 fresh IVF/ICSI cycles were captured, including 18 693 singleton live births. IVF success (live birth, singleton or multiple; LB), singleton gestation and singleton gestation-adjusted BW were analysed using logistic and linear regression models adjusting for patient/treatment characteristics and clinic-specific effects.

MAIN RESULTS AND THE ROLE OF CHANCE

Culture medium type was shown to have some impact on LBR (multivariable logistic regression, (MRL); post-regression Wald test, P < 0.001), but not on BW (MLR; post-regression Wald test, P = 0.215). However, blastocyst culture had the largest observed effect on odds of LBR (odds ratio (OR) = 1.35, CI: 1.29–1.42), increased the risk of pre-term birth even when controlling for oxygen tension (MLR; OR = 1.42, CI: 1.23–1.63), and gestation-adjusted BW (MLR, β = 38.97 g, CI: 19.42–58.53 g) when compared to cleavage-stage embryo culture. We noted a very strong effect of clinic site on both LBR and BW, thus confounding between treatment practices and clinic site may have masked the effect of culture conditions.

LIMITATIONS, REASONS FOR CAUTION

Larger datasets with more inter-centre variation are also needed, with key embryo culture variables comprehensively recorded in national treatment registries.

WIDER IMPLICATIONS OF THE FINDINGS

This study is the largest investigation of laboratory environmental effects in IVF on both LBR and singleton BW. Our findings largely agree with the literature, which has failed to show a consistent advantage of one culture media type over another. However, we noted some association of LBR with medium type, and the duration of embryo exposure to laboratory conditions (blastocyst culture) was associated with both LBR and singleton health at birth. Because of the strong effect of clinic site noted, further randomized controlled trials are needed in order to reliably determine the effect of embryo culture on IVF success rates and the growth and health of subsequent offspring.

STUDY FUNDING/COMPETING INTEREST(S)

This study was funded by the EU FP7 project grant EpiHealthNet (FP7-PEOPLE-2012-ITN -317 146). The authors have no competing interests to declare.

Associated perinatal determinants of vanishing twin pregnancies achieved by in vitro fertilization vs. spontaneous conception

PURPOSE

To evaluate whether vanishing twin (VT) pregnancies following spontaneous conception have a more adverse perinatal outcome than those conceived after assisted reproduction techniques.

METHODS

The retrospective cohort study consisted of 316 VT pregnancies derived from a hospital database between January 1994 and January 2016 (81 after IVF/ICSI and 235 after spontaneous conception).

RESULTS

VT was significantly more prevalent after spontaneous conception (in 22.0% of twins) than after IVF/ICSI (in 14.5% of twins). VT pregnancies were significantly more associated with pre-gestational and gestational diabetes mellitus (GDM) in IVF/ICSI pregnancies compared to those spontaneously conceived [adjusted odds ratio (AOR): 4.12 and 11.1, respectively]. IVF-related placental insertion abnormalities were significantly higher in VT pregnancies. A high risk for VT was recorded in the spontaneous group for those who had previously undergone an induced abortion (AOR 0.56) or second-trimester fetal loss (AOR 0.67). The VT phenomenon was a major prognosticator of intrauterine growth retardation (IUGR) for the remaining fetus in IVF pregnancies (AOR 5.12). After controlling for covariates conjointly, advanced age (AOR 1.3), GDM (AOR 2.1), hypertensive disorders (AOR 3.5), primiparity (AOR 3.8), and placentation anomalies all represented independent risk factors for VT in IVF pregnancies.

CONCLUSIONS

IVF/ICSI poses a higher risk for an adverse perinatal outcome following VT pregnancies as compared with those spontaneously conceived.

Effect of frozen and fresh embryo transfers on the birthweight of live-born twins

OBJECTIVE

To explore the influence of frozen embryo transfer (FET) and fresh embryo transfer (Fresh) on the birthweight of live-born twins.

STUDY DESIGN

A total of 8482 live-born twins were studied. The proportions of small for gestational age (SGA) and large for gestational age (LGA), the mean birthweight and the z score of live-born twins in the two groups were compared. Multiple linear regression analysis was used to evaluate the relationship between confounding factors and the birthweight of live-born twins.

RESULTS

The proportion of SGA infants significantly decreased as BMI increased (BMI < 20, 6.1 %; 20 ≤ BMI≤25, 4.1 %; BMI > 25, 3.6 %; P<0.05). The proportion of LGA infants significantly increased as BMI increased (BMI < 20, 20.5 %; 20 ≤ BMI≤25, 25.2 %; BMI > 25, 30.7 %; P<0.0001). The proportion of SGA infants was significantly lower in the FET group than in the Fresh group, whereas the proportion of LGA infants was significantly higher in the former than in the latter. The absolute mean birthweight of live-born twins was significantly higher in the FET group compared with the Fresh group (2579 ± 458 vs. 2534 ± 465, P < 0.0001). The mean z score of the FET group was also significantly higher than that of the Fresh group (0.420 vs. 0.240, P < 0.0001). Multiple linear regression analysis indicated that FET was a more significant factor than fresh embryo transfer in influencing the birthweight of live-born twins.

CONCLUSION

FET significantly increased the birthweight of live-born twins compared with fresh embryo transfer.

Neonatal outcomes of singleton live births with vanishing twin syndrome following double embryos transfer in assisted reproductive technology: a retrospective cohort study

Background

Women with vanishing twin syndrome are associated with increased risks of adverse neonatal outcomes, such as preterm birth (PTB) and low birthweight (LBW), compared with those in singleton live births following single embryo transfer (SET) in assisted reproductive technology (ART).

Methods

Anonymized data on all cycles performed in China were obtained from the Reproductive Medicine Department at the Third Affiliated Hospital of Zhengzhou University, which had involved 127597 cycles following double embryos transfer (DET), including 54585 fresh embryos transfer (ET) cycles and 73012 frozen embryos transfer (FET) cycles. In addition, the obstetric outcomes, such as gestation age, PTB, small for gestation age (SGA), birthweight (BW), LBW, congenital malformation, pediatric admission and Neonatal Intensive Care Unit (NICU) admission in the fresh ET and FET cycles, were analyzed. Moreover, logistic regression analysis was performed to adjust the confounders, including age of women, body weight index (BMI), value of AMH, infertile years, current cycle, antral follicles, cause of infertility, number of oocytes retrieved, endometrial thickness at the date of transplantation, number of high-quality embryos, and embryo stage.

Results

In the fresh ET cycles, the BW and gestational age in study group were lower than those in control group, which were (2962.4 ± 563.1vs. 3104.9 ± 498. 5, p = 0.000) and (262.8 ± 8.4 vs. 268.9 ± 13.9, p = 0.000), respectively. Relative to control group, the study group was linked with increased risks of PTB (adjusted odds ratio (aOR) 2.45, 95% CI:1.98–3.03, adjusted p = 0.000), LBW (aOR2.11, 95% CI:1.67–2.65, adjusted p = 0.000), pediatric admission (aOR 2.55, 95% CI2.07–3.13, adjusted p = 0.000), and NICU admission (aOR 1.98, 95% CI1.32–2.96, adjusted p = 0.001), but there were no statistically significant differences in the risks of SGA (aOR 1.09, 95% CI0.82–1.45, adjusted p = 0.960) and congenital malformation (aOR 0.94, 95% CI0.53–1.68, adjusted p = 0.640) between the two groups. In the FET cycles, the gestational age and BW in study group were lower than those in control group, which were (263.0 ± 15.7vs. 273.0 ± 10.5, p = 0.000) and (3099 ± 662.1vs. 3352 ± 671.5), respectively. The study group was associated with increased risks of PTB (aOR2. 45, 95% CI: 2.23–3.43, adjusted p = 0.000), LBW (aOR 2.67, 95% CI: 2.13–3.34, adjusted p = 0.000), pediatric admission (aOR2.62, 95% CI2.14–3.21, adjusted p = 0.000), and NICU admission (aOR 2.22, 95% CI1.43, 3.46, adjusted p = 0.001) compared with those in control group, but differences in the risks of SGA (aOR 0.98, 95% CI0.71–1.36, adjusted p = 0.730) and congenital malformation (aOR 0.99, 95% CI 0.60,1.63, adjusted p = 0.940) between the two groups were not statistically significant.

Conclusions

Our study finds that singleton live births with VTS have higher risks of LBW, PTB, pediatric admission and NICU admission than those without VTS in both the fresh and frozen cycles, even after adjusting for confounders. However, no increased risks of SGA or congenital malformation are observed in singleton live births in both the fresh and frozen ART cycles following DET.

Single embryo transfer improve the perinatal outcome in singleton pregnancy

Background and objectives: Most of previous studies are comparing the perinatal outcome on singleton babies. There has been no study evaluating the possible effect of singleton embryo transfer on the perinatal outcomes in initial singleton pregnancy resulting from fresh embryo transfer. The purpose of our study is to access the effect of embryo transfer number on obstetric and perinatal risks in order to examine the role of single embryo transfer on perinatal outcomes on initial singleton pregnancy.Materials and methods: This study is a retrospective cohort study and analyzed 6439 fresh embryo transfer women. 1647 initial singleton pregnancy patients were divided into one of the following three groups according to the embryo transfer number: group A (n = 94): single embryo transfer (SET); group B (n = 1321): double embryo transfer (DET); group C (n = 262): triple embryo transfer (TET). The miscarriage rate and the ectopic pregnancy rate was compared between group A and group B, group C. 1273 live birth patients were divided into three groups too. The obstetrics outcomes and perinatal outcomes between group A and group B, group C.Results: There were 94 singleton pregnancy patients in unselective single embryo transfer. Comparing with double embryo transfer, the early miscarriage rate was higher, but late miscarriage rate, ectopic rate, and live birth rate were comparable between two groups. The obstetrics outcomes were comparable between single embryo transfer and other two groups. Although there was no significant difference between group A and other two groups, preterm birth rate, extremely preterm birth rate, low-birth weight rate and very low-birth weight rate increased with the increase of embryo transfer number. The mean delivery weight was highest in singleton babies in single embryo transfer group. It is higher in group A comparing with group B (3440.4 versus 3320.7 g) and comparing with group C (3440.4 versus 3277.4 g).Conclusions: Single embryo transfer was associated with a better perinatal outcome such as preterm birth and low-birth weight in a singleton pregnancy. The mean birth weight was significantly higher in single embryo transfer group too. Single embryo transfer is a reasonable option to reach the goal of in vitro-fertilization - a healthy singleton neonate.