Implications of assisted reproductive technologies on term singleton birth weight: an analysis of 25,777 children in the national assisted reproduction registry of Japan

Comparison of Fetal Crown-Rump Length Measurements between Thawed and Fresh Embryo Transfer

Background and Objectives: Neonates born from thawed embryo transfers tend to have a significantly higher birthweight compared to those from fresh embryo transfers. The aim of this study was to compare the crown-rump length (CRL) between thawed and fresh embryos to investigate the potential causes of different growth patterns between them. Materials and Methods: This was a retrospective study (July 2010-December 2023) conducted at the Third Department of Obstetrics and Gynecology, School of Medicine, Faculty of Health Sciences, Aristotle University of Thessaloniki, Greece. In total, 3082 assisted reproductive technology (ART) pregnancies (4044 embryos) underwent a routine scan at 11+0-13+6 gestational weeks and were included in the study. Maternal age, the type of embryo transfer (thawed vs. fresh, donor vs. their own oocytes), CRL, twin and singleton gestations were analyzed. Results: The mean maternal age in thawed was significantly higher than in fresh embryos (39.8 vs. 35.8 years, p-value < 0.001). The mean CRL z-score was significantly higher in thawed compared to fresh embryo transfers (0.309 vs. 0.199, p-value < 0.001). A subgroup analysis on singleton gestations showed that the mean CRL z-score was higher in thawed blastocysts compared to fresh (0.327 vs. 0.215, p-value < 0.001). Accordingly, an analysis on twins revealed that the mean CRL z-score was higher in thawed blastocysts (0.285 vs. 0.184, p-value: 0.015) and in oocytes' recipients compared to own oocytes' cases (0.431 vs. 0.191, p-value: 0.002). Conclusions: The difference in CRL measurements between thawed and fresh embryos may be a first indication of the subsequent difference in sonographically estimated fetal weight and birthweight. This finding highlights the need for additional research into the underlying causes, including maternal factors and the culture media used.

Cardiovascular Risk in Pediatrics: A Dynamic Process during the First 1000 Days of Life

The early childhood period, encompassing prenatal and early stages, assumes a pivotal role in shaping cardiovascular risk factors. We conducted a narrative review, presenting a non-systematic summation and analysis of the available literature, focusing on cardiovascular risk from prenatal development to the first 1000 days of life. Elements such as maternal health, genetic predisposition, inadequate fetal nutrition, and rapid postnatal growth contribute to this risk. Specifically, maternal obesity and antibiotic use during pregnancy can influence transgenerational risk factors. Conditions at birth, such as fetal growth restriction and low birth weight, set the stage for potential cardiovascular challenges. To consider cardiovascular risk in early childhood as a dynamic process is useful when adopting a personalized prevention for future healthcare and providing recommendations for management throughout their journey from infancy to early adulthood. A comprehensive approach is paramount in addressing early childhood cardiovascular risks. By targeting critical periods and implementing preventive strategies, healthcare professionals and policymakers can pave the way for improved cardiovascular outcomes. Investing in children's health during their early years holds the key to alleviating the burden of cardiovascular diseases for future generations.

The Associated Factors of Low Birthweight Among Term Singletons in Japan: A Pregnancy Birth Registry Analysis

BACKGROUND

Progress in reducing the global low birthweight (LBW) has been insufficient. Although the focus has been on preventing preterm birth, evidence regarding LBW in term births is limited. Despite its low preterm birth prevalence, Japan has a higher LBW proportion than other developed countries. This study aimed to examine the prevalence of LBW in term singleton births and its associated factors using a national database.

METHODS

We retrospectively analyzed the data of neonates registered in the Japan Society of Obstetrics and Gynecology Successive Pregnancy Birth Registry System who were born 2013-2017. Exclusion criteria included stillbirths, delivery after 42 gestational weeks, and missing data. Logistic regression analyses were performed to investigate the maternal and perinatal factors associated with LBW in term singletons using the data of 715,414 singleton neonates.

RESULTS

The overall prevalence of LBW was 18.3%, and 35.7% of LBWs originated from singleton term pregnancies. Multiple logistic regression analyses indicated that both modifiable and non-modifiable factors were independently associated with LBW in term neonates. The modifiable maternal factors included pre-pregnancy underweight, inadequate gestational weight gain, and smoking during pregnancy, while the non-modifiable factors included younger maternal age, nulliparity, hypertensive disorders of pregnancy, cesarean section delivery, female offspring, and congenital anomalies.

CONCLUSION

Using the Japanese pregnancy birth registry data, more than one-third of LBWs were found to originate from singleton term pregnancies. Both modifiable and non-modifiable factors were independently associated with LBW in term neonates. Prevention strategies on modifiable risk factor control will be effective in reducing LBW worldwide.

Obstetric and neonatal outcomes after natural versus artificial cycle frozen embryo transfer and the role of luteal phase support: a systematic review and meta-analysis

BACKGROUND

The number of frozen embryo transfers (FET) has increased dramatically over the past decade. Based on current evidence, there is no difference in pregnancy rates when natural cycle FET (NC-FET) is compared to artificial cycle FET (AC-FET) in subfertile women. However, NC-FET seems to be associated with lower risk of adverse obstetric and neonatal outcomes compared with AC-FET cycles. Currently, there is no consensus about whether NC-FET needs to be combined with luteal phase support (LPS) or not. The question of how to prepare the endometrium for FET has now gained even more importance and taken the dimension of safety into account as it should not simply be reduced to the basic question of effectiveness.

OBJECTIVE AND RATIONALE

The objective of this project was to determine whether NC-FET, with or without LPS, decreases the risk of adverse obstetric and neonatal outcomes compared with AC-FET.

SEARCH METHODS

A systematic review and meta-analysis was carried out. A literature search was performed using the following databases: CINAHL, EMBASE, and MEDLINE from inception to 10 October 2022. Observational studies, including cohort studies, and registries comparing obstetric and neonatal outcomes between singleton pregnancies after NC-FET and those after AC-FET were sought. Risk of bias was assessed using the ROBINS-I tool. The quality of evidence was evaluated using the Grading of Recommendations Assessment, Development and Evaluation approach. We calculated pooled odds ratios (ORs), pooled risk differences (RDs), pooled adjusted ORs, and prevalence estimates with 95% CI using a random effect model, while heterogeneity was assessed by the I2.

OUTCOMES

The conducted search identified 2436 studies, 890 duplicates were removed and 1546 studies were screened. Thirty studies (NC-FET n = 56 445; AC-FET n = 57 231) were included, 19 of which used LPS in NC-FET. Birthweight was lower following NC-FET versus AC-FET (mean difference 26.35 g; 95% CI 11.61-41.08, I2 = 63%). Furthermore NC-FET compared to AC-FET resulted in a lower risk of large for gestational age (OR 0.88, 95% 0.83-0.94, I2 = 54%), macrosomia (OR 0.81; 95% CI 0.71-0.93, I2 = 68%), low birthweight (OR 0.81, 95% CI 0.77-0.85, I2 = 41%), early pregnancy loss (OR 0.73; 95% CI 0.61-0.86, I2 = 70%), preterm birth (OR 0.80; 95% CI 0.75-0.85, I2 = 20%), very preterm birth (OR 0.66, 95% CI 0.53-0.84, I2 = 0%), hypertensive disorders of pregnancy (OR 0.60, 95% CI 0.50-0.65, I2 = 61%), pre-eclampsia (OR 0.50; 95% CI 0.42-0.60, I2 = 44%), placenta previa (OR 0.84, 95% CI 0.73-0.97, I2 = 0%), and postpartum hemorrhage (OR 0.43; 95% CI 0.38-0.48, I2 = 53%). Stratified analyses on LPS use in NC-FET suggested that, compared to AC-FET, NC-FET with LPS decreased preterm birth risk, while NC-FET without LPS did not (OR 0.75, 95% CI 0.70-0.81). LPS use did not modify the other outcomes. Heterogeneity varied from low to high, while quality of the evidence was very low to moderate.

WIDER IMPLICATIONS

This study confirms that NC-FET decreases the risk of adverse obstetric and neonatal outcomes compared with AC-FET. We estimate that for each adverse outcome, use of NC-FET may prevent 4 to 22 cases per 1000 women. Consequently, NC-FET should be the preferred treatment in women with ovulatory cycles undergoing FET. Based on very low quality of evidence, the risk of preterm birth be decreased when LPS is used in NC-FET compared to AC-FET. However, because of many uncertainties-the major being the debate about efficacy of the use of LPS-future research is needed on efficacy and safety of LPS and no recommendation can be made about the use of LPS.

Current Status and Issues of the Japan Oncofertility Registry

Purpose: Fertility preservation (FP) is becoming increasingly common among child, adolescent, and young-adult (CAYA) patients with cancer. However, Japan has long lacked definite estimates of utilization rates for FP services among CAYA patients with cancer, and little is known about disease/FP outcomes among users. Therefore, the Japan Society for Fertility Preservation (JSFP) launched the Japan Oncofertility Registry (JOFR) in 2018 and started the online registration of information regarding primary disease, FP, and data on prognosis and pregnancy outcomes. This study reports the analytical results of FP data registered in the JOFR as of 2021. Methods: Data about patients' primary disease(s), treatment courses, cancer and pregnancy outcomes, and specific procedures were extracted from the JOFR and analyzed. Results: In 2021, 1244 patients received counseling or treatment related to FP (540 males, 704 females). While the numbers of males in each age group were approximately equal, most females were aged between 31 and 40 years. In total, 490 male and 540 female patients underwent FP procedures. Leukemia, testicular cancer, and malignant lymphoma accounted for the majority of male cases seeking treatment, whereas breast cancer was the primary disease in two-thirds of the females. Since 1999, 395 patients have accumulatively experienced subsequent pregnancy. Conclusions: As of January 2022, >7000 cases from >100 fertility facilities have been registered in the JOFR. In the future, maintaining JOFR to disseminate information on cancer prognoses, pregnancy rates, and other oncofertility outcomes is expected to drive further expansion of oncofertility services in Japan.

Influence of maternal age on the birthweight of infants delivered from frozen-thawed blastocyst transfer cycles

The aim of this study was to investigate whether maternal age had an effect on the birthweight of singletons delivered from frozen-thawed blastocyst transfer (FBT) cycles. A total of 1203 FBT cycles occurring between July 2011 and June 2021 at a single centre were retrospectively analysed. Based on the maternal age at FBT, the patients were divided into four groups: <30, 30-34, 35-37, and ≥38 years of age. Main outcomes measured included singleton birthweights, preterm births, large-for-gestational-age (LGA) and small-for-gestational-age (SGA) live births among the groups. There was no significant difference in birth weight among the four groups, while the highest birth weight was found in the <30 years group. The incidence of very preterm births and very low birth weights demonstrated an increasing trend with age; on the contrary, the incidence of preterm births, low birth weight (LBW), high birth weight and LGA and SGA live births gradually decreased with increasing age, but these differences were not statistically significant among groups (P>0.05, respectively). Although the proportion of females was lower than that of males, the difference was not statistically significant among the groups. After adjusting for possible confounders, maternal age was found to have no effect on adverse neonatal outcomes in the regression analyses (P>0.05). Birthweight in singleton births from FBT was not affected by maternal age.

Does endometrial thickness affect birth weight and serum levels of pregnancy-associated plasma protein-A in frozen cycles?

OBJECTIVE

To investigate whether endometrial thickness (EMT) affects birth weight and maternal serum pregnancy-associated plasma protein-A (PAPP-A) level in singleton pregnancies following frozen-thawed blastocyst transfer (FET).

METHODS

This retrospective study included women who underwent first-trimester combined screening for aneuploidy after FET, and subsequently delivered a singleton live birth after 24 weeks of gestation at a private in-vitro fertilization centre. The subjects were stratified into three groups based on EMT percentiles: <7.7 mm (<10th percentile), 7.7-12 mm (10-90th percentile), and > 12 mm (>90th percentile). Multi-variable linear regression analysis was undertaken to identify the association between birth weight and EMT after adjusting for variables with p < 0.1 on univariate analysis.

RESULTS

In total, 560 women met the inclusion criteria. Mean (±standard deviation) birth weight was 3127 ± 783 g in those with EMT < 7.7 mm, 3225 ± 644 g in those with EMT 7.7-12 mm, and 3256 ± 599 g in those with EMT > 12 mm (p = 0.577). Mean PAPP-A and PAPP-A < 0.5 rates were similar in the three groups. On multi-variate analysis, maternal serum PAPP-A was found to be a significant predictor of birth weight (p = 0.013), but EMT was not found to be predictive of birth weight on univariate or multi-variate analysis.

CONCLUSION

This study provided a new angle to evaluate the association between EMT and neonatal birth weight by analysing this association along with maternal serum PAPP-A as a marker for placental function, suggesting that EMT is not an independent factor for neonatal birth weight.

Anthropometric measurements of term singletons at 6 years of age born from fresh and frozen embryo transfer: A multicenter prospective study in Japan

Purpose

The purpose of this study is to compare anthropometric measurements between term singletons conceived via fresh embryo transfer (FreET) and frozen embryo transfer (FET) and those born via natural conception (NC) or fertility treatments milder than assisted reproductive technology (non-ART) at 6 years of age.

Methods

A total of 8149 children were enrolled, and questionnaires about anthropometric measures (weight, height, BMI) were addressed to parents, when the children were 1.5, 3, and 6 years of age. A total of 3299 term singletons were enrolled at birth: 533, 476, 916, and 1374 in the NC, non-ART, FreET, and FET groups, respectively.

Results

A total of 1635 term singletons (290, 176, 467, and 702 in the NC, non-ART, FreET, and FET groups respectively) were enrolled until 6 years of age (follow-up rate, approximately 50%). When non-ART group was used as control, the FreET children were 1.0 cm taller than the non-ART children at 6 years of age, after adjusting for confounding factors. However, no differences were observed in the anthropometric data among the non-ART, ART, and NC children at 6 years of age.

Conclusion

At 6 years of age, term singletons were taller in the FreET group than in the non-ART group, after adjusting for confounders.

High birth weight and greater gestational age at birth in singletons born after frozen compared to fresh embryo transfer

OBJECTIVE

While many studies agree that the fetal birth weight is higher after frozen embryo transfer (FET), few studies have explored the difference in fetal weight change during such pregnancies. This cohort study was to identify the difference in fetal birth weight and gestational age at birth between singletons born following fresh ET and those born following FET.

MATERIALS AND METHODS

This was a hospital-based cohort study using clinical data from the Kaohsiung Chang Gung Memorial Hospital Obstetric and Neonatal Database from January 1, 2007, to December 1, 2018. A sample of 784 eligible women who had singleton pregnancies and live-born deliveries after 428 fresh ET or 356 FET between January 2007 and December 2018.

RESULTS

Compared with those in the fresh ET group, singletons in the FET group had higher birth weight (3137 g [2880-3441 g] vs. 3060 g [2710-3340 g], p < 0.05), were born later (39.0 weeks of gestation [38.0-40.0 weeks] vs. 38.0 weeks of gestation [37.0-39.0 weeks], p < 0.05), and had a lower incidence of preterm birth (10.4% vs. 15.2%, p < 0.05). The difference in birth weight was not associated with maternal body weight (BW) or body mass index, increase in maternal BW in the third trimester, but related to the total increase in maternal BW during pregnancy.

CONCLUSIONS

The birthweight of singletons born following FET and fresh ET became significant in the late third trimester. The main reason is that singletons conceived from FET were at a lower relative risk of preterm delivery and had a higher gestational age at birth.

Greater estimated fetal weight and birth weight in IVF/ICSI pregnancy after frozen-thawed vs fresh blastocyst transfer: prospective cohort study with novel unified modeling methodology

OBJECTIVE

To compare, using a unified approach, standardized estimated fetal weight (EFW) trajectories from the second trimester to birth and birth-weight (BW) measurements in in-vitro fertilization/intracytoplasmic sperm injection (IVF/ICSI) pregnancies obtained after frozen-thawed vs fresh blastocyst transfer (BT).

METHODS

This was a secondary analysis of a prospective longitudinal cohort study performed at the Fetal Medicine and Obstetric Departments of San Raffaele Hospital in Milan, Italy, from January 2016 to December 2020. Eligible for inclusion were singleton viable gestations conceived by autologous IVF/ICSI conception after fresh or frozen-thawed BT that underwent standard fetal biometry assessment at 19-41 weeks and had BW measurements available. All ultrasound assessments were performed by operators blinded to the employment of cryopreservation. Patients with twin gestation, significant pregestational disease, miscarriage, major fetal abnormalities and use of other types of medically assisted reproduction techniques were excluded. EFW and BW Z-scores and their trajectories were analyzed using general linear models (GLM) and logistic regression with a unified modeling methodology based on the Fetal Medicine Foundation fetal and neonatal population weight charts, adjusting for major confounders. Differences between prenatal EFW and postnatal BW centiles in the two groups were assessed and compared using contingency tables, χ² test and conversion of prenatal to postnatal centiles.

RESULTS

A total of 631 IVF/ICSI pregnancies were considered, comprising 263 conceived following fresh BT and 368 after frozen-thawed BT. A total of 1795 EFW observations were available (n = 715 in fresh BT group and n = 1080 in frozen-thawed BT group; median of three observations per patient). EFW and BW < 10^th centile were significantly more frequent in the fresh than in the frozen-thawed BT group (P = 0.003 and P < 0.001, respectively). EFW and BW > 90^th centile were significantly more frequent in the frozen-thawed vs fresh BT group (P = 0.034 and P = 0.002, respectively). GLM showed significantly decreasing EFW Z-scores with advancing gestational age (GA) in both groups. The effect of GA was assumed to be equal in the two study groups, as no significant interaction effect was found. Smoothed mean EFW Z-scores from 19 weeks of gestation to term and smoothed mean BW Z-scores were both significantly higher in the frozen-thawed compared with the fresh BT group (EFW Z-score, 0.70 ± 1.29 vs 0.28 ± 1.43; P < 0.001; BW Z-score, 0.04 ± 1.08 vs -0.31 ± 1.28; P < 0.001). Mean smoothed EFW Z-score values in the frozen-thawed vs fresh BT groups were 1.01 ± 0.12 vs 0.60 ± 0.08 at 19-27 weeks, 0.36 ± 0.07 vs -0.06 ± 0.04 at 28-35 weeks and -0.66 ± 0.01 vs -0.88 ± 0.02 at 36-41 weeks. Mean smoothed BW Z-score values in the frozen-thawed vs fresh BT groups were -0.80 ± 0.14 vs -1.20 ± 0.10 at 28-35 weeks and 0.22 ± 0.16 vs -0.24 ± 0.14 at 36-41 weeks. Assessment of EFW and BW concordance showed a significantly greater rate of postnatal confirmation of prenatally predicted small-for-gestational age (SGA) < 10^th centile in the fresh compared with the frozen-thawed BT group (P < 0.001), whereas the rate of postnatal confirmation of large-for-gestational age (LGA) > 90^th centile was significantly higher in the frozen-thawed vs the fresh BT group (P < 0.001). Logistic regression analysis showed that the smoothed rate of EFW < 3^rd centile was about 6-fold higher in the fresh vs frozen-thawed BT group (P < 0.001), whereas the smoothed rates of EFW 90^th -97^th centile and > 97^th centile were nearly double in the frozen-thawed compared with the fresh BT group (P < 0.05 and P < 0.001, respectively).

CONCLUSIONS

Robust novel unified prenatal-postnatal modeling in IVF/ICSI pregnancies after frozen-thawed or fresh BT from 19 weeks of gestation to birth showed non-divergent growth trajectories, with higher EFW and BW Z-scores in the frozen-thawed vs fresh BT group. The mean EFW Z-scores in both IVF/ICSI groups were greater than those expected for natural conceptions, being highest in the midtrimester and decreasing with advancing gestation in both groups, becoming negative after 32 weeks in the fresh and after 35 weeks in the frozen-thawed BT group. Mean BW Z-scores were negative in both groups, with lower values in preterm fetuses, and increased with advancing gestation, becoming positive at term in the frozen-thawed BT group. IVF/ICSI conceptions from frozen-thawed as compared to fresh BT presented increased rate of LGA and reduced rate of SGA both prenatally and postnatally. © 2021 International Society of Ultrasound in Obstetrics and Gynecology.

The effects of post-frozen-thawed embryo transfer pregnancy on early fetal development

AIM

Frozen-thawed embryo transfer (FET) has gained popularity as an assistive reproductive technology despite its increased risk of large-for-gestational-age offspring. This study aimed to analyze the effect of FET on fetal development, particularly the growth rate and estimated fetal weight (EFW) throughout pregnancy.

METHODS

This was a single-center, retrospective study that examined 97 patients with FET conception and 477 patients with natural conception (NC) who underwent labor and delivery at our clinic between December 2015 and June 2019. Crown-rump length (CRL) in the first trimester and EFW measurements in the second and third trimesters were obtained from transabdominal ultrasound records. Birthweight was adjusted for sex, parity, and gestational age. Regression coefficients of CRL, EFW, and birthweight were compared between the FET and NC groups to examine the growth rate. Multiple regression analysis was performed to determine the relationship between birth size and baseline characteristics.

RESULTS

The growth rate was higher in the first trimester in the FET group than in the NC group (difference: 0.19 mm/day, p = 0.018). CRL, EFW, and adjusted birthweight were higher in the FET group than in the NC group throughout pregnancy. The factors associated with the development of larger offspring through FET than through NC were advanced maternal age, primiparity, cesarean section delivery, and high birthweight.

CONCLUSIONS

Throughout pregnancy, FET resulted in a larger offspring than in NC, with accelerated growth observed only during the first trimester. Thus, FET highly affects early fetal development.

What are the causes for low birthweight in Japan? A single hospital-based study

Low-birthweight (LBW; <2,500 g) babies are at a higher risk of poor educational achievement, disability, and metabolic diseases than normal-birthweight babies in the future. However, reliable data on factors that contribute to LBW have not been considered previously. Therefore, we aimed to examine the distribution of the causes for LBW. A retrospective review of cases involving 4,224 babies whose mothers underwent perinatal care at Keio University Hospital between 2013 and 2019 was conducted. The LBW incidence was 24% (1,028 babies). Of the 1,028 LBW babies, 231 babies were from multiple pregnancies. Of the 797 singleton LBW babies, 518 (65%) were born preterm. Obstetric complications in women with preterm LBW babies included premature rupture of membrane or labor onset (31%), hypertensive disorders of pregnancy (HDP, 64%), fetal growth restriction (24%), non-reassuring fetal status (14%), and placental previa/vasa previa (8%). Of the 279 term LBW babies, 109 (39%) were small for gestational age. Multiple logistic regression analyses revealed the following factors as LBW risk factors in term neonates: low pre-pregnancy maternal weight, inadequate gestational weight gain, birth at 37 gestational weeks, HDP, anemia during pregnancy, female sex, and neonatal congenital anomalies. HDP was an LBW risk factor not only in preterm births but also in term births. Our results suggest that both modifiable and non-modifiable factors are causes for LBW. It may be appropriate to consider a heterogeneous rather than a simple classification of LBW and to evaluate future health risks based on contributing factors.

The effect of repeated cryopreservation and thawing using cryotip on the clinical outcomes of embryos

PURPOSE

To compare the clinical outcomes of embryo transfers that were cryopreserved and thawed two or three times with those cryopreserved and thawed once by CryoTip.

METHODS

Data for 388 single cryopreserved-thawed blastocyst transfer cycles, performed from April 2012 to March 2014, were assessed. The blastocysts were classified into three groups: blastocysts (A) cryopreserved once, (B) cryopreserved twice, and (C) cryopreserved three times.

RESULTS

The pregnancy rate was 43.8% (134/306) in group A and 46.3% (38/82) in group B, while the miscarriage rate was 29.1% (39/134) in group A and 23.7% (9/38) in group B. The rate of improvement/maintenance of blastocyst grade was 84.0% (257/306) in group A and 80.5% (66/82) in group B. The pregnancy and miscarriage rates of the blastocysts that showed improvement/maintenance in the grade were 45.9% (118/257) and 29.7% (35/118) in group A and 48.5% (32/66) and 21.9% (7/32) in group B, respectively. The pregnancy rate was 33.3% (2/6), while the miscarriage rate was 0.0% (0/2) in group C.

CONCLUSIONS

Pregnancy rates achieved with re-cryopreserved and rethawed blastocyst transfer were comparable to those achieved with single cryopreserved-thawed blastocyst transfer.

Genetic counseling prior to assisted reproductive technology

BACKGROUND

Reproductive medicine deals with fertility and is closely related to heredity. In reproductive medicine, it is necessary to provide genetic information for the patients prior to assisted reproductive technology (ART). Japan Society for Reproductive Medicine (JSRM) requires doctors involved in reproductive medicine to have standard knowledge of reproductive genetics and knowledge of reproductive medicine, which is covered in their publication, "required knowledge of reproductive medicine."

METHODS

With the aim of providing straightforward explanations to patients in the clinical situation at pre-ART counseling, we provide the following five topics, such as (a) risk of birth defects in children born with ART, (b) chromosomal abnormalities, (c) Y chromosome microdeletions (YCMs), (d) possible chromosomal abnormal pregnancy in oligospermatozoa requiring ICSI (intracytoplasmic sperm injection), and (e) epigenetic alterations.

MAIN FINDINGS

The frequency of chromosome abnormalities in infertile patients is 0.595%-0.64%. YCMs are observed in 2%-10% of severe oligospermic men. High incidence of spermatozoa with chromosomal abnormalities has been reported in advanced oligospermia and asthenozoospermia that require ICSI. Some epigenetic alterations were reported in the children born with ART.

CONCLUSION

Certain genetic knowledge is important for professionals involved in reproductive medicine, even if they are not genetic experts.

Herausforderung Adenomyose – operative, endokrine und reproduktionsmedizinische Therapieoptionen

Die Adenomyose ist durch endometriale Zellen im Myometrium charakterisiert. Zu den klinischen Beschwerden gehören Schmerzen, Blutungsstörungen und beeinträchtigte Fertilität. Die Abklärung beinhaltet eine gute Anamnese und die Bildgebung mit transvaginalem Ultraschall (TVUS) sowie ggf. Magnetresonanztomographie. Klassisch zeigt sich die Adenomyose im TVUS durch partielle Aufhebung der Junktionalzone. Die Therapie erfolgt ganzheitlich und beinhaltet ein gutes Schmerzmanagement. Bei jungen Patientinnen sollte eine endokrine Therapie erfolgen. Die Kinderwunschtherapie kann mit einer 3‑monatigen Down-Regulation mit Gonadotropin-Releasing-Hormon(GnRH)-Analoga eingeleitet werden. Bei notwendiger In-vitro-Fertilisation haben Protokolle mit ultralanger Down-Regulation oder zeitlich versetztem Embryotransfer nach GnRH-Analoga bessere Resultate gezeigt. Bei fortgeschrittener Erkrankung, abgeschlossener Familienplanung oder Therapieresistenz kommt die operative Sanierung oder Hysterektomie infrage.

Greater fetal crown-rump length growth with the use of in vitro fertilization or intracytoplasmic sperm injection conceptions after thawed versus fresh blastocyst transfers: secondary analysis of a prospective cohort study

OBJECTIVE

To compare first-trimester fetal crown-rump length (CRL) measurements in pregnancies obtained after thawed blastocyst transfer versus fresh blastocyst transfer after in vitro fertilization (IVF)/intracytoplasmic sperm injection (ICSI).

DESIGN

Prospective longitudinal cohort study of CRL Z scores with adjustment for major confounders.

SETTING

University-affiliated obstetrics, fetal medicine, and fertility units.

PATIENT(S)

Singleton gestations conceived via IVF/ICSI and fresh or thawed blastocyst transfer with ultrasound performed at 6-14 weeks of gestational age.

INTEVENTION

None.

MAIN OUTCOME MEASURE(S)

CRL Z scores.

RESULT(S)

A total of 365 IVF/ICSI pregnancies were recruited (fresh: 161; thawed: 204). The mean CRL Z score at 6-14 weeks was significantly greater in thawed versus fresh transfers. Different growth trajectories between thawed and fresh transfers were detected: Mean CRL Z score was 0 at 65 days in fresh versus 80 days in frozen. Comparisons of both fresh and thawed transfers with reference values from the general population confirmed significantly lower CRL Z scores in both IVF/ICSI groups (P<.001). The risks of CRL <5th percentile in fresh versus thawed were, respectively 68% vs. 40% at 6 weeks and 2% vs. 1% at 14 weeks. A significant positive correlation between CRL Z scores and birth weight Z scores was found only for fresh transfers, not for thawed.

CONCLUSION(S)

At 6-14 weeks, thawed blastocyst transfers after IVF/ICSI conceptions present greater CRLs compared with fresh, and both IVF/ICSI groups show smaller CRLs than the general population. This effect is particularly evident before 9 weeks and it may favor birth weight difference of thawed versus fresh BT pregnancies.

Six-year follow-up of children born from vitrified oocytes

RESEARCH QUESTION

Are children born from vitrified-warmed oocytes physically or mentally different from naturally conceived children?

DESIGN

Intracytoplasmic sperm injection (ICSI) of vitrified-warmed oocytes was performed for 282 patients (307 cycles) from August 2000 to March 2020. Long-term follow-up of children born from vitrified-warmed oocytes was performed via a questionnaire that was sent to the parents at regular intervals from 3 to 72 months after the child's birth. Questionnaires were sent 11 times from birth to the age of 6 years. The development of motor function and mental status was evaluated as the primary outcome, based on the reported data. Subsequently, patients were divided into four groups by age at oocyte retrieval (20-29, 30-34, 35-39, and 40 years or older). Clinical outcomes were calculated as a secondary outcome.

RESULTS

For the 282 patients, the birth of 116 babies was reported (110 singletons and three sets of twins), and seven cases are, at the time of writing, unconfirmed. The results of the survey found physical parameters in singletons to be equivalent to the nationally reported average data issued by the Ministry of Health, Labor and Welfare of Japan.

CONCLUSION

This is the first follow-up report of children born from vitrified-warmed oocytes followed by ICSI. The data suggested that the responses from the study participants on the mental and physical development of children were comparable to the data reported by the government, although more responses from patients should be collected to allow further study.

Perinatal and maternal outcomes after frozen versus fresh embryo transfer cycles in women of advanced maternal age

OBJECTIVE

The delay of childbearing in women has become a worldwide issue in recent decades. The application of assisted reproductive technology in women of advanced maternal age (AMA) is increasing. Evidence on the safety and outcomes of frozen embryo transfer (FET) compared with fresh embryo transfer (ET) in AMA women is still lacking. Therefore, the objective of the present study was to compare perinatal and maternal outcomes after autologous FET and fresh ET cycles in women of AMA.

STUDY DESIGN

A retrospective study of 1663 FET and 3964 fresh ET cycles in reproductive medical centers from 2009 to 2014. Women who aged ≥35 years and had clinical pregnancies after autologous frozen or fresh ET were included. The main perinatal outcomes included birth weight, gestational age, rates of preterm birth, macrosomia, low birth weight (LBW), and very low birth weight. The main maternal outcomes included rates of hypertensive disorders of pregnancy, gestational diabetes mellitus, and preterm premature rupture of the membranes.

RESULTS

Women who underwent FET had an increased risk of hypertensive disorders of pregnancy [1.1 % vs. 0.4 %, adjusted OR (95 % CI): 2.76 (1.39-5.51); p = 0.004]. Singletons born after FET had significantly higher mean birth weight (3388.78 ± 538.47 vs. 3316.19 ± 549.08; p = 0.001). Furthermore, increased risk of macrosomia [13.5 % vs. 10.4 %, adjusted OR (95 % CI): 1.35 (1.07-1.71); p = 0.013] and decreased risk of LBW [3.6 % vs. 5.3 %, adjusted OR (95 % CI): 0.67 (0.45-1.00); p = 0.048] were found in singletons born after FET.

CONCLUSIONS

Perinatal risks of AMA patients are higher in FET than in fresh ET, including higher birth weight, risks of macrosomia in singleton births, and hypertensive disorders of pregnancy.

Examination of fetal growth trajectories following infertility treatment

PURPOSE

The objective of this retrospective cohort study was to compare fetal growth during the second and third trimesters for ovulation induction with intrauterine insemination (IUI), fresh embryo transfer (ET), frozen embryo transfer (FET), and spontaneous conception following infertility.

METHODS

Three hundred ninety-five women with viable pregnancies confirmed at a single academic fertility center participated. All women achieved pregnancy either by treatment or spontaneously after a diagnosis of infertility. Inclusion criteria included autologous singleton pregnancies. Exclusion criteria included pregnancies from donor oocytes, twins, unavailable ultrasound data, and treatment methods with small number of participants. Primary outcomes of interest were head circumference (HC), abdominal circumference (AC), HC/AC ratio, and estimated fetal weight (EFW). Conditional growth curve models were created, and growth curves were selected for each outcome of interest.

RESULTS

For ovulation induction with IUI, fresh ET, FET, and spontaneous conception, the slope analysis of growth curves for per-week growth rate of HC, AC, HC/AC ratio, and EFW demonstrated no difference. A subgroup analysis of fresh ET and FET groups, for same outcomes, also showed no difference.

CONCLUSION

These findings contribute to the very limited literature on fetal growth trajectories following infertility treatment and suggest no significant differences in fetal growth for ovulation induction with IUI, fresh ET, FET, and spontaneous conception following infertility. It is possible there were no differences in growth trajectories between these conception methods because the majority of children born following infertility are of normal birth weight. While results are reassuring, further research with larger populations is warranted.

Anogenital distance in newborn infants conceived by assisted reproduction and natural conception

RESEARCH QUESTION

Does anogenital distance (AGD) differ in newborn infants conceived through assisted reproduction technology (ART) compared with those conceived naturally?

DESIGN

This case-control study looked at anthropometric and anogenital measurements in 247 male and 200 female newborns born after ART (n = 121) or natural conception (n = 326), within 24 h of birth. Anogenital measurements included distance from the centre of the anus to the anterior clitoris (AGDAC) and to the posterior fourchette (AGDAF) in female infants, and from the centre of the anus to the posterior base of the scrotum (AGDAS) and to the anterior base of the penis (AGDAP) in male infants.

RESULTS

ART mothers were older, more likely to be nulliparous and delivered by Caesarean section at an earlier gestational week. AGDAS of male infants was approximately twice the AGDAF of female infants (17.6 ± 5.0 versus 9.1 ± 3.6 mm). AGDAF in female infants conceived by ART compared with those conceived naturally was not significantly different (8.8 ± 3.6 versus 9.3 ± 3.6 mm; P = 0.404). AGDAC were also comparable for both groups (27.4 ± 6.3 versus 27.7 ± 7.1 mm; P = 0.770). In male infants, no significant difference was seen between ART and natural conception groups in terms of AGDAS (17.4 ± 4.6 versus 17.7 ± 5.2 mm, P = 0.742) and AGDAP (37.5 ± 6.6 versus 38.0 ± 6.7 mm, P = 0.589). When adjusted for gestational age, weight, length and head circumference, mode of conception was not associated with differences in any of the anogenital measurements.

CONCLUSIONS

AGD measurements in infants conceived by ART are no different from those of infants conceived naturally.

Endometrial thickness is associated with incidence of small-for-gestational-age infants in fresh in vitro fertilization-intracytoplasmic sperm injection and embryo transfer cycles

OBJECTIVE

To investigate whether endometrial thickness (EMT) is associated with adverse obstetric and neonatal outcomes in fresh in vitro fertilization/intracytoplasmic sperm injection-embryo transfer (IVF/ICSI-ET) cycles.

DESIGN

Retrospective cohort study.

SETTING

University-based reproductive medical center.

PATIENT(S)

Women under the age of 42 years who underwent IVF/ICSI treatment and received fresh ET in our unit from January 2017 to December 2018, resulting in a live singleton birth.

INTERVENTION(S)

Controlled ovarian hyperstimulation and IVF/ICSI; fresh ET.

MAIN OUTCOME MEASURE(S)

Birth weight, gestational age, small for gestational age (SGA), large for gestational age (LGA), placenta previa, placental abruption, hypertensive disorders, and gestational diabetes mellitus.

RESULT(S)

The risk of being born SGA was statistically significantly increased in the EMT ≤7.5 mm group compared with those from the EMT >12 mm group (adjusted odds ratio [aOR] 2.391; 95% confidence interval [CI], 1.155-4.950). Moreover, maternal body mass index, secondary infertility, preterm delivery, and hypertensive disorders were all independent predictors for SGA. The mean birth weights of singletons in women with EMT ≤7.5 mm were lower than in the groups with EMT >7.5-12 mm and EMT >12 mm (3.25 ± 0.56 kg vs. 3.38 ± 0.51 kg and 3.39 ± 0.53 kg, respectively).

CONCLUSION(S)

After fresh IVF/ICSI-ET, the risk of SGA was increased twofold in women with EMT ≤7.5 mm compared with women with EMT >12 mm. We suggest that women with a thin EMT after obtaining a pregnancy by IVF should receive improved prenatal care to reduce the risk of delivering a SGA infant.

Increased blood pressure and impaired endothelial function after accelerated growth in IVF/ICSI children

STUDY QUESTION

What is the effect of growth velocity (height and weight) in early infancy on metabolic end-points and endothelial function in children born after ART?

SUMMARY ANSWER

Neonatal, infant and childhood growth is positively related to blood pressure in 9-year-old IVF/ICSI offspring, while growth in childhood was negatively associated with endothelial function.

WHAT IS KNOWN ALREADY

Offspring of pregnancies conceived after ART are at risk for later cardiometabolic risk factors. It is well established that early growth is related to numerous later cardiometabolic risk factors such as high blood pressure. This concept is known as the Developmental Origin of Health and Disease theory.

STUDY DESIGN SIZE DURATION

The relation between early growth and later cardiometabolic risk profile was studied in the MEDIUM-KIDS study, a prospective observational cohort study in children born after an IVF/ICSI treatment. In 131 children (48.1% males) at the average age of 9.4 years, cardiometabolic outcomes were assessed and growth data from birth until age 9 years were collected from child welfare centers.

PARTICIPANTS/MATERIALS SETTINGS METHODS

The following cardiometabolic outcomes were assessed: blood pressure, skinfolds, lipid spectrum, hair cortisone and glucose and insulin levels. Data on maximum skin perfusion after transdermal delivery of acetylcholine as a measure of endothelial function were collected.Growth charts were obtained electronically from child welfare centers, which offer free consultations and vaccinations to all Dutch children. At these centers, height and weight are recorded at predefined ages. Growth was defined as z-score difference in weight between two time points. Multivariable linear regression analysis was used to model the relation between growth and cardiometabolic outcomes. The following growth windows were -studied simultaneously in each model: 0-1 month, 1-3 months, 3-6 months, 6-11 months, 11-24 months and 2-6 years. The model was adjusted for height growth in all intervals except for 0-1 month.

MAIN RESULTS AND THE ROLE OF CHANCE

In multivariable linear regression analyses, multiple growth windows were positively associated with blood pressure, for example growth from 2-6 years was significantly related to systolic blood pressure: B = 4.13, P = 0.005. Maximum skin perfusion after acetylcholine was negatively associated with height-adjusted weight gain from 2 to 6 years: B = -0.09 (log scale), P = 0.03. Several growth windows (weight 1-3 months, 3-6 months, 6-11 months, 11-24 months, 2-6 years) were positively linked with total adiposity. Lipids, glucose tolerance indices and cortisone were not related to growth.

LIMITATIONS REASONS FOR CAUTION

This study is of modest size and of observational nature, and we did not include a control group. Therefore, we cannot assess whether the observed associations are causal. It is also not possible to analyze if our observations are specific for, or exacerbated in, the ART population. Ideally, a control group of naturally conceived siblings of IVF/ICSI children should simultaneously be studied to address this limitation and to assess the impact of the ART procedure without the influence of parental (subfertility) characteristics.

WIDER IMPLICATIONS OF THE FINDINGS

The results of this study contribute to our understanding of the reported increased risk for hypertension in ART offspring. We speculate that early, accelerated growth may be involved in the reported increased risk for hypertension in ART offspring, with endothelial dysfunction as a possible underlying mechanism. However, additional research into the mechanisms involved is required.

STUDY FUNDING/COMPETING INTERESTS

The study was financially supported by the March of Dimes, grant number #6-FY13-153. The sponsor of the study had no role in study design, data collection, data analysis, data interpretation or writing of the paper. The authors have no conflict of interest to declare.

TRIAL REGISTRATION NUMBER

NTR4220.

Fresh versus frozen embryo transfer has no effect on childhood weight

OBJECTIVE

To evaluate the effect of frozen, compared with fresh, embryo transfer on neonatal and pediatric weight and weight gain trajectory.

DESIGN

Retrospective cohort study.

SETTING

Academic medical center.

PATIENT(S)

Women who underwent fresh or frozen embryo transfer at the Mayo Clinic from 2010 to 2014. All included embryo transfers resulted in a singleton live birth. Children were followed from birth to at least 18 months. When possible, growth was evaluated to 5 years of age.

INTERVENTIONS(S)

Fresh versus frozen embryo transfer.

MAIN OUTCOME MEASURE(S)

Propensity score methodology was used to balance the two groups by maternal characteristics and gestational age before evaluating outcomes. Each infant and childhood growth measurement was compared between the two groups.

RESULT(S)

Of the 136 women, 87 underwent a fresh embryo transfer and 49 underwent a frozen embryo transfer. Birth length and head circumference were significantly different in infants delivered after fresh versus frozen embryo transfer. There was a statistically significant difference in birth weight between infants born after fresh versus frozen embryo transfer. However, this difference did not persist when adjusted for gestational age, sex, and maternal factors. Childhood growth measurements including age- and sex-specific weight, and body mass index percentiles were not significantly different between groups.

CONCLUSION(S)

This study confirmed an association of frozen embryo transfer and increased birth weight, but the association did not persist when controlling for confounding maternal factors. We found no effect of fresh versus frozen embryo transfer on neonatal weight and childhood weight gain trajectory.

Male subfertility and the risk of major birth defects in children born after in vitro fertilization and intracytoplasmic sperm injection: a retrospective cohort study

Background

Children born after intracytoplasmic sperm injection (ICSI) are at increased risk of specific major birth defects compared with children born after in vitro fertilization (IVF). However, whether this risk is due to the treatment itself (i.e., IVF or ICSI) or underlying male subfertility is unknown. This study investigated the associations between male subfertility and the risk of major birth defects in children born after IVF and ICSI.

Methods

We conducted a retrospective cohort study using data from the Japanese assisted reproductive technology registry between 2007 and 2014. Fresh embryo transfer cycles registered from 2007 to 2014 that resulted in singleton live births, still births, or selective terminations were included (n = 59,971). Major birth defects were defined by the US Centers for Disease Control and Prevention guidelines, excluding chromosomal abnormalities. Odds ratios (ORs) and 95% confidence intervals (CIs) were calculated using generalized estimating equations adjusting for potential confounders.

Results

Major birth defects were reported in 626/59,971 (1.04%) cases. Among IVF cycles, male subfertility was associated with significantly greater risks of hypospadias (3/3163 [0.09%] vs 4/28,671 [0.01%], adjusted OR = 6.85, 95% CI 2.05–22.9, P = 0.002) and atrial septal defects (4/3163 [0.13%] vs 9/28,671 [0.03%], adjusted OR = 3.98, 95% CI 1.12–14.1, P = 0.03) compared with fertile men. Subgroup analysis using sperm parameters showed that oligozoospermia (i.e., sperm concentrations < 15 million/mL) was significantly associated with a greater risk of ventricular septal defects compared with normal sperm concentrations in IVF pregnancies (5/868 [0.58%] vs 60/28,090 [0.21%], adjusted OR = 2.68, 95% CI 1.15–6.27, P = 0.02), and severe oligozoospermia (i.e., sperm concentrations < 5 million/mL) was significantly associated with an increased risk of hypospadias compared with normal sperm concentrations in ICSI pregnancies (5/3136 [0.16%] vs 5/16,865 [0.03%], adjusted OR = 3.88, 95% CI 1.14–13.2, P = 0.03).

Conclusions

The results of this exploratory study suggest that underlying male subfertility may play a role in the risk of major birth defects related to ICSI and IVF. Further research, including systematic reviews adjusting for confounders, is required to confirm the associations between male subfertility and major cardiac and urogenital birth defects.

Electronic supplementary material

The online version of this article (10.1186/s12884-019-2322-7) contains supplementary material, which is available to authorized users.

Large for gestational age and macrosomia in singletons born after frozen/thawed embryo transfer (FET) in assisted reproductive technology (ART)

Increase in success rates with frozen embryo transfer (FET) and reduced risk of ovarian hyperstimulation syndrome (OHSS) and multiple pregnancies has lead to a steady rise in FET. Further, FET is associated with lower risk of prematurity and low birth weight in singletons, when compared with fresh transfer. However, there is a growing concern of increased risk of large for gestational (LGA) and/or macrosomic children after FET. Macrosomic/LGA births have a higher risk of cesarean section, fetal hypoxia and stillbirth. Improvements in cryopreservation techniques indicate that FET is a trend expected to continue and a freeze-all policy has lately been introduced. With this review, we wished to evaluate the association between FET and LGA and/or macrosomia. We searched electronic databases on January 12, 2018. Ten studies on LGA and six studies on macrosomia were eligible for meta-analysis. We found that the risk of LGA in FET was increased 1.5-fold (AOR = 1.50 95% CI 1.44-1.57 p < 0.001) compared to fresh cycles and 1.3-fold (AOR = 1.31 95% CI 1.20-1.43 p < 0.001) compared to natural conception (NC). Similarly we found a 1.7-fold increased risk of macrosomia in FET compared to fresh transfer (AOR = 1.71 95% CI 1.59-1.83 p < 0.001) and a 1.4-fold increased risk compared to NC (AOR = 1.42 95% CI 1.17-1.71 p < 0.001). Whether the increased risk of LGA and macrosomia is associated with higher long-term health risks remains unknown. Future studies should explore epigenetics modifications in children born after FET and predictors of long-term diseases need to be examined further with longitudinal studies.

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.

Obstetrical complications of thin endometrium in assisted reproductive technologies: a systematic review

PURPOSE

The aim of the systematic review is to describe the obstetrical complications associated with pregnancies in the context of a thin endometrial lining.

METHODS

Systematic review of the literature.

RESULTS

Patients who conceive in the setting of a thin endometrium have a significantly increased risk of early pregnancy loss, namely miscarriage and ectopic pregnancy. These patients also have a twofold increase in low birth weight and preterm delivery, as well as a significantly higher risk of intrauterine growth restriction and composite adverse perinatal outcomes.

CONCLUSIONS

In addition to the lower probability of conception, a thin endometrium in assisted reproductive technologies appears to be associated with both early and late pregnancy complications. These pregnancies thus warrant special attention and close follow-up from obstetricians.

The growth of assisted reproductive treatment-conceived children from birth to 5 years: a national cohort study

BACKGROUND

Birth weight and early child growth are important predictors of long-term cardiometabolic disease risk, in line with the Developmental Origins of Health and Disease hypothesis. As human assisted reproductive technologies (ARTs) occur during the sensitive periconceptional window of development, it has recently become a matter of urgency to investigate risk in ART-conceived children.

METHODS

We have conducted the first large-scale, national cohort study of early growth in ART children from birth to school age, linking the register of ART, held by the UK's Human Fertilisation and Embryology Authority, to Scottish maternity and child health databases.

RESULTS

In this study of 5200 ART and 20,800 naturally conceived (NC) control children, linear regression analysis revealed the birthweight of babies born from fresh embryo transfer cycles is 93.7 g [95% CI (76.6, 110.6)g] less than NC controls, whereas babies born from frozen embryo transfer (FET) cycles are 57.5 g [95% CI (30.7, 86.5)g] heavier. Fresh ART babies grew faster from birth (by 7.2 g/week) but remained lighter (by 171 g), at 6-8 weeks, than NC babies and 133 g smaller than FET babies; FET and NC babies were similar. Length and occipital-frontal circumference followed the same pattern. By school entry (4-7 years), weight, length and BMI in boys and girls conceived by fresh ART and FET were similar to those in NC children.

CONCLUSIONS

ART babies born from fresh embryo transfer grow more slowly in utero and in the first few weeks of life, but then show postnatal catch up growth by school age, compared to NC and FET babies. As low birth weight and postnatal catch-up are independent risk factors for cardiometabolic disease over the life-course, we suggest that further studies in this area are now warranted.

Recent advances in oncofertility care worldwide and in Japan

BACKGROUND

Oncofertility is a crucial facet of cancer supportive care. The publication of guidelines for the cryopreservation of oocytes and ovarian tissue is becoming increasingly prevalent in Japan and an updated overview is necessary.

METHODS

In order to provide an updated overview of oncofertility care, original research and review articles were searched from the PubMed database and compared in order to present clinical care in Japan.

RESULTS

In Western countries, various methods for ovarian stimulation, such as the combined use of aromatase inhibitors and random-start protocols, have been reported. Although ovarian tissue cryopreservation, mainly performed via the slow-freezing method, also has yielded >100 live births, the optimal indications and procedures for the auto-transplantation of cryopreserved tissue have been under investigation. In Japan, however, vitrification is prevalent for ovarian tissue cryopreservation, although its efficacy has not yet been established. The quality of network systems for providing oncofertility care in Japan varies greatly, based on the region.

CONCLUSION

There remain many issues in the optimization of oncofertility care in Japan. Along with the regional oncofertility networks, the creation of "oncofertility navigators" from healthcare providers who are familiar with oncofertility, such as nurses, psychologists, and embryologists, could be useful for supplementing oncofertility care coordination, overcoming the issues in individual regions.

Effect of embryo and blastocyst transfer on the birthweight of live-born singletons from FET cycles

PURPOSE

To evaluate the effect of culture duration (embryo (day 3) transfer vs. blastocyst (day 5-6) transfer) on the birthweight of singletons from frozen embryo transfer (FET) cycles.

METHODS

A total of 1092 singletons were analyzed in this retrospective study. The distribution of large for gestational age (LGA) infants, the mean birthweight, and z scores of singletons were compared between the day 3 and day 5-6 transfer groups. Multiple linear regression analysis was performed to evaluate the relationships between confounding factors and singleton birthweight.

RESULTS

The proportion of LGA infants significantly increased with BMI (BMI < 20, 12.8%; 20 ≤ BMI ≤ 25, 23.2%; BMI > 25, 32.3%; P < 0.0001). However, the proportions of small for gestational age (SGA) and LGA infants were not significantly different between day 3 and day 5-6 transfers. The absolute mean birthweight of singletons was not significantly different between day 3 transfer (3422 ± 547 g) and day 5-6 transfer (3433 ± 559 g; P = 0.732). The z scores (calculated from a reference population) of singletons were also not significantly different between the two groups (0.499 vs. 0.533, P = 0.625). Multiple linear regression analysis showed that maternal BMI, gestational age, and infant gender had significant effects on singleton birthweight, while culture duration (P = 0.731) did not significantly affect singleton birthweight.

CONCLUSIONS

In vitro culture duration did not affect the birthweight of newborns resulting from day 3 to day 5-6 transfers in FET cycles.

Identifying a possible factor for the increased newborn size in singleton pregnancies after assisted reproductive technology using cryopreserved embryos, in comparison with fresh embryos

PURPOSE

To determine whether the cycle regimens that are used for endometrial preparation are associated with the birthweight (BW) after assisted reproductive technology (ART) using frozen-thawed embryo transfer (FET).

METHODS

The BW of singletons who were born by ART using FET was compared retrospectively, according to whether a FET was conducted in a hormone replacement therapy cycle (HRT, n = 403) or an ovulatory cycle (OVL, n = 117). The BW after timed intercourse (NAT, n = 162) also was investigated.

RESULTS

There were no significant differences in the age of the mothers, percentage of primiparas, gestational periods, Body Mass Index, and sex ratio between the HRT and OVL cycles. The average BW from HRT was significantly greater than that of OVL. The BW from HRT was also greater, compared with NAT, while statistical significance was not achieved between OVL and NAT. The putative factors affecting the BW, such as ovarian stimulation protocols, endometrial thickness, and the stage and quality of embryos, could not explain the difference in the BW between the HRT and OVL cycles.

CONCLUSION

An increased BW from ART using FET seems to be ascribable to conditions of the endometrium, but not cryopreservation procedures per se, which might provide a mechanistic framework for understanding heavier neonates who are born by FET.

Clinical outcomes of frozen embryo versus fresh embryo transfer following in vitro fertilization: a meta-analysis of randomized controlled trials

PURPOSE

To examine available data from randomized controlled trials to assess if the freeze-all embryo and subsequent frozen-thawed embryo transfer (FET) results in better clinical outcomes than fresh embryo transfer (ET).

METHODS

Meta-analysis.

RESULTS

We conducted an electronic literature search on PubMed and Embase databases and manually supplemented another 2 articles from relevant citations. Seven studies were finally included in the meta-analysis,including 1141 women who underwent fresh embryo transfer and 1079 who underwent frozen embryo transfer. The results of the meta-analysis suggested that the live birth rate [RR (95% CI) 1.18 (1.08-1.30), P = 0.0003] and clinical pregnancy rate [RR (95% CI) 1.10 (1.02-1.19), P = 0.02] were significantly higher in FET group. Miscarriage rate [RR (95% CI) 0.62 (0.48-0.80), P = 0.0002], and moderate to severe OHSS occurrence rate [RR (95% CI) 0.22 (0.12 to 0.39), P < 0.00001] were significantly lower in FET group. Differences of biochemical pregnancy rate, ongoing pregnancy rate and implantation rate between the two groups did not reach the statistical significance.

CONCLUSIONS

Our results suggest that the IVF/ICSI with FET is more efficient and less risky for OHSS compared with ET. However, we should comprehensively inform patients with advantages, disadvantages and potential risks related to embryo cryopreservation, and carefully assess their fertility conditions to make the most beneficial clinical decision.

The high concentration of progesterone is harmful for endometrial receptivity and decidualization

Progesterone is required for the establishment and maintenance of mammalian pregnancy and widely used for conservative treatment of luteal phase deficiency in clinics. However, there are limited solid evidences available for the optimal timing and dose of progesterone therapy, especially for the possible adverse effects on implantation and decidualization when progesterone is administrated empirically. In our study, mouse models were used to examine effects of excess progesterone on embryo implantation and decidualization. Our data indicate that excess progesterone is not only harmful for mouse implantation, but also impairs mouse decidualization. In excess progesterone-treated mice, the impaired LIF/STAT3 pathway and dysregulated endoplasmic reticulum stress may lead to the inhibition of embryo implantation and decidualization. It is possible that the decrease in birth weight of excess progesterone-treated mice is due to a compromised embryo implantation and decidualization. Furthermore, excess progesterone compromises in vitro decidualization of human endometrial stromal cells.

Influence of cryopreservation on perinatal outcome after blastocyst- vs cleavage-stage embryo transfer: systematic review and meta-analysis

OBJECTIVE

To compare the perinatal outcomes of singleton pregnancies resulting from blastocyst- vs cleavage-stage embryo transfer and to assess whether they differ between fresh and frozen embryo transfer cycles.

METHODS

A systematic review of the literature was carried out using the Scopus, MEDLINE and ISI Web of Science databases with no time restriction. We included only peer-reviewed articles involving humans, in which perinatal outcomes of singleton pregnancies after blastocyst-stage embryo transfer were compared with those after cleavage-stage embryo transfer. Primary outcomes were preterm birth before 37 weeks and low birth weight (< 2500 g). Secondary outcomes were very preterm birth before 32 weeks, very low birth weight (< 1500 g), small-for-gestational-age (SGA), large-for-gestational-age (LGA), perinatal mortality and congenital anomaly. A meta-analysis was performed using a random-effects model. Three subgroups were evaluated: fresh only, frozen only and fresh plus frozen embryo transfer cycles.

RESULTS

From a total of 3928 articles identified, 14 were selected for qualitative/quantitative analysis. Significantly higher incidences of preterm birth < 37 weeks (11 studies, n = 106 629 participants; risk ratio (RR), 1.15 (95% CI, 1.05 - 1.25); P = 0.002) and very preterm birth < 32 weeks (seven studies, n = 103 742; RR, 1.16 (95% CI, 1.02-1.31); P = 0.03) were observed after blastocyst- than after cleavage-stage embryo transfer in fresh cycles. However, the risk of preterm and very preterm birth was similar after blastocyst- and cleavage-stage transfers in frozen and fresh plus frozen cycles. Overall effect size analysis revealed fewer SGA deliveries after blastocyst- compared with cleavage-stage transfer in fresh cycles but a similar number in frozen cycles. Conversely, more LGA deliveries were observed after blastocyst- compared with cleavage-stage transfer in frozen cycles (two studies, n = 39 044; RR, 1.18 (95% CI, 1.09-1.27); P < 0.0001) and no differences between the two groups in fresh cycles (four studies, n = 42 982; RR, 1.14 (95% CI, 0.97-1.35); P = 0.11). There were no differences with respect to low birth weight, very low birth weight or congenital anomalies between blastocyst- and cleavage-stage transfers irrespective of the cryopreservation method employed. Only one study reported a higher incidence of perinatal mortality after blastocyst- vs cleavage-stage embryo transfer in frozen cycles, while no differences were found in fresh cycles.

CONCLUSIONS

Our results suggest that cryopreservation of embryos can influence outcome of pregnancy conceived following blastocyst- vs cleavage-stage embryo transfer in terms of preterm birth, very preterm birth, LGA, SGA and perinatal mortality. Caution should be exercised in interpreting these findings given the low level of evidence and wide heterogeneity of the studies. Copyright © 2017 ISUOG. Published by John Wiley & Sons Ltd.

Pregnancy, birth, and infant outcomes by maternal fertility status: the Massachusetts Outcomes Study of Assisted Reproductive Technology

BACKGROUND

Births to subfertile women, with and without infertility treatment, have been reported to have lower birthweights and shorter gestations, even when limited to singletons. It is unknown whether these decrements are due to parental characteristics or aspects of infertility treatment.

OBJECTIVE

The objective of the study was to evaluate the effect of maternal fertility status on the risk of pregnancy, birth, and infant complications.

STUDY DESIGN

All singleton live births of ≥22 weeks' gestation and ≥350 g birthweight to Massachusetts resident women in 2004-2010 were linked to hospital discharge and vital records. Women were categorized by their fertility status as in vitro fertilization, subfertile, or fertile. Women whose births linked to in vitro fertilization cycles from the Society for Assisted Reproductive Technology Clinic Outcomes Reporting System were classified as in vitro fertilization. Women with indicators of subfertility but not treated with in vitro fertilization were classified as subfertile. Women without indicators of subfertility or in vitro fertilization treatment were classified as fertile. Risks of 15 adverse outcomes (gestational diabetes, pregnancy hypertension, antenatal bleeding, placental complications [placenta abruptio and placenta previa], prenatal hospitalizations, primary cesarean delivery, very low birthweight [<1500 g], low birthweight [<2500 g], small-for-gestation birthweight [z-score ≤-1.28], large-for-gestation birthweight [z-score ≥1.28], very preterm [<32 weeks], preterm [<37 weeks], birth defects, neonatal death [0-27 days], and infant death [0-364 days of life]) were modeled by fertility status with the fertile group as reference and the subfertile group as reference, using multivariate log binomial regression and reported as adjusted risk ratios and 95% confidence intervals.

RESULTS

The study population included 459,623 women (441,420 fertile, 8054 subfertile, and 10,149 in vitro fertilization). Women in the subfertile and in vitro fertilization groups were older than their fertile counterparts. Risks for 6 of 6 pregnancy outcomes and 6 of 9 infant outcomes were increased for the subfertile group, and 5 of 6 pregnancy outcomes and 7 of 9 infant outcomes were increased for the in vitro fertilization group. For 4 of the 6 pregnancy outcomes (uterine bleeding, placental complications, prenatal hospitalizations, and primary cesarean) and 2 of the infant outcomes (low birthweight and preterm) the risk was greater in the in vitro fertilization group, with nonoverlapping confidence intervals to the subfertile group, indicating a substantially higher risk among in vitro fertilization-treated women. The highest risks for the in vitro fertilization women were uterine bleeding (adjusted risk ratio, 3.80; 95% confidence interval, 3.31-4.36) and placental complications (adjusted risk ratio, 2.81; 95% confidence interval, 2.57-3.08), and for in vitro fertilization infants, very preterm birth (adjusted risk ratio, 2.13; 95% confidence interval, 1.80-2.52), and very low birthweight (adjusted risk ratio, 2.15; 95% confidence interval, 1.80-2.56). With subfertile women as reference, risks for the in vitro fertilization group were significantly increased for uterine bleeding, placental complications, prenatal hospitalizations, primary cesarean delivery, low and very low birthweight, and preterm and very preterm birth.

CONCLUSION

These analyses indicate that, compared with fertile women, subfertile and in vitro fertilization-treated women tend to be older, have more preexisting chronic conditions, and are at higher risk for adverse pregnancy outcomes, particularly uterine bleeding and placental complications. The greater risk in in vitro fertilization-treated women may reflect more severe infertility, more extensive underlying pathology, or other unfavorable factors not measured in this study.

Retrospective comparative study of the factors affecting birthweights in frozen-thawed embryo transfer, compared to fresh embryo transfer

Aim

Several studies have indicated that the cause of the increased birthweight of frozen‐thawed embryos was associated with assisted reproductive technology (ART) procedures, such as cryopreservation. In the present study, the mean birthweight of singletons was compared between the ovulatory and hormone replacement therapy (HRT) cycles in order to investigate the primary factor that leads to higher birthweights from frozen‐thawed embryo transfer (FET).

Methods

This retrospective study was carried out from January 2011 to December 2014 on 2738 singletons who were born at 37‐41 weeks’ gestation, following ART in a single facility. The mean birthweight of the singletons who were born after a fresh embryo transfer (ET) was compared to the mean birthweight of the singletons who were born after a FET. In the FET cycles, the mean birthweight of the singletons was compared between the ovulatory and HRT cycles.

Results

The mean birthweight of the singletons who were born after a FET was significantly higher than that of the singletons who were born after a fresh ET. In the FET cycles, the birthweight from the HRT cycles was significantly higher than that from the ovulatory cycles. Among the HRT cycles, there was no difference between the birthweight of the singleton who were born from a blastocyst transfer and those who were born from a cleavage‐stage ET.

Conclusion

The primary factor to affect the birthweight of singletons might be the pre/postET hormonal environment of the endometrium and not the stage of the transferred embryo nor the frozen‐thawed procedure itself.

Endometrial thickness influences neonatal birth weight in pregnancies with obstetric complications achieved after fresh IVF-ICSI cycles

PURPOSE

Pregnancy-associated complications, duration of gestation and parity are well-known predictors of neonatal birth weight. Assisted reproductive technology (ART) affects neonatal birth weight as well. Endometrial thickness as measured on the day of HCG triggering may therefore impact on the neonatal birth weight.

METHODS

The data of 764 singleton deliveries achieved after fresh transfer between November 1997 and 2014 were collected retrospectively with the intention to analyze the relationship of maternal and neonatal characteristics with endometrial thickness and the possible predictive value of endometrial thickness on neonatal birth weight.

RESULTS

Higher maternal age (p < 0.001), diminished ovarian reserve (p < 0.001), endometriosis (p = 0.008) and hypogonadotropic hypogonadism (p < 0.001) predicted thin endometrium. Neonatal birth weight (p = 0.004), longer duration of pregnancy (p = 0.008), parity (p = 0.026) and higher maternal BMI (p = 0.003) were correlated significantly with the degree of endometrial proliferation. Endometrial thickness strongly predicted neonatal birth weight (p = 0.004). After adjusting regression analysis for maternal age and BMI, parity, neonatal gender and pregnancy duration, endometrial thickness remained predictive for neonatal birth weight in pregnancies with obstetric complications (p = 0.017). In uneventful pregnancies duration and parity are determinants of neonatal birth weight.

CONCLUSIONS

Our findings suggest that endometrial thickness is an additional ART-related factor influencing neonatal birth weight. This finding should be confirmed in large cohort studies.

Pre-pregnancy BMI-specific optimal gestational weight gain for women in Japan

Background

The Institute of Medicine (IOM) guidelines are the most widely used guidelines on gestational weight gain; however, accumulation of evidence that body composition in Asians differs from other races has brought concern regarding whether their direct application is appropriate. We aimed to study to what extent optimal gestational weight gain among women in Japan differs by pre-pregnancy body mass index (BMI) and to compare estimated optimal gestational weight gain to current Japanese and Institute of Medicine (IOM) recommendations.

Methods

We retrospectively studied 104,070 singleton pregnancies among nulliparous women in 2005–2011 using the Japanese national perinatal network database. In five pre-pregnancy BMI sub-groups (17.0–18.4, 18.5–19.9, 20–22.9, 23–24.9, and 25–27.4 kg/m²), we estimated the association of the rate of gestational weight gain with pregnancy outcomes (fetal growth, preterm delivery, and delivery complications) using multivariate regression.

Results

Weight gain rate associated with the lowest risk of adverse outcomes decreased with increasing BMI (12.2 kg, 10.9 kg, 9.9 kg, 7.7 kg, and 4.3 kg/40 weeks) for the five BMI categories as described above, respectively. Current Japanese guidelines were lower than optimal gains, with the lowest risk of adverse outcomes for women with BMI below 18.5 kg/m², and current IOM recommendations were higher than optimal gains for women with BMI over 23 kg/m².

Conclusion

Optimal weight gain during pregnancy varies largely by pre-pregnancy BMI, and defining those with BMI over 23 kg/m² as overweight, as proposed by the World Health Organization, may be useful when applying current IOM recommendations to Japanese guidelines.

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We estimated gestational weight gain that optimizes pregnancy outcomes in Japanese.

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Optimal gain was 12.2 kg/40 weeks for pre-pregnancy BMI 17.0–18.4 kg/m².

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Optimal gain was 4.3 kg/40 weeks for pre-pregnancy BMI 25.0–27.4 kg/m².

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Current national guidelines are too low for women with pre-pregnancy BMI < 18.5 kg/m².

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BMI > 23 kg/m² should be defined as overweight if applying IOM recommendations.

Deferred Frozen Embryo Transfer: What Benefits can be Expected from this Strategy in Patients with and without Endometriosis?

Progress with cryopreservation techniques have enabled development of the deferred frozen-thawed embryo transfer (DET) strategy as an alternative to relying on fresh embryo transfers.

With DET, the entire embryo cohort is cryopreserved, and embryo transfer is then performed in a subsequent cycle that takes place separately from the controlled ovarian stimulation (COS).

Initially developed to limit the risk of ovarian hyperstimulation syndrome that occurs with high responders, this strategy has been applied extensively with other populations in an effort to improve implantation rates. The assumption is that COS, which is essential for in vitro fertilization/intra cytoplasmic sperm injection (IVF/ICSI) procedures to obtain a multi-follicular development, could have a detrimental impact on the endometrium as a result of greatly elevated levels of steroids. It is currently not clear whether the DET strategy can be generally applied to all women requiring an IVF/ICSI procedure.

The objectives of this literature review regarding DET, were hence: (i) to present the scientific background that contributed to extensive adoption of this technique, (ii) to detail the pregnancy outcomes and potential obstetric and neonatal consequences, (iii) to report on its ability to prevent risks induced by COS, and (iv) to propose indications for the DET strategy in clinical practice.

GnRH agonist administration prior to embryo transfer in freeze-all cycles of patients with endometriosis or aberrant endometrial integrin expression

Prolonged gonadotrophin-releasing hormone agonist (GnRHa) administration before IVF with fresh embryo transfer to patients with endometriosis or aberrant endometrial integrin expression (-integrin) improves outcomes but may suppress ovarian response and prevents elective cryopreservation of all embryos. This retrospective cohort pilot study evaluates freeze-all cycles with subsequent prolonged GnRHa before embryo transfer in these populations. Patients from 2010 to 2015 who met inclusion criteria and received a long-acting GnRHa every 28 days twice before FET were evaluated. A subset underwent comprehensive chromosomal screening (CCS) after trophectoderm biopsy. Three groups were identified: Group 1: + CCS, +endometriosis (20 patients, 20 transfers); Group 2: +CCS, -integrin (12 patients, 13 transfers); Group 3: no CCS, +endometriosis or -integrin (10 patients, 12 transfers); Group 4: all transfers after CCS for descriptive comparison only (n = 2809). Baseline characteristics were similar among Groups 1-3 except that the mean surgery to oocyte aspiration interval was longer for Group 1 than Group 3. Implantation and ongoing pregnancy rates were statistically similar among the three groups and compared favourably to Group 4. A non-significant trend towards improved outcomes was noted in Group 1. Prolonged GnRHa after freeze-all in these patients avoids excessive ovarian suppression and results in excellent outcomes.

Birthweights and Down syndrome in neonates that were delivered after frozen-thawed embryo transfer: The 2007-2012 Japan Society of Obstetrics and Gynecology National Registry data in Japan

Aim

To evaluate the use of frozen embryos on the outcome of assisted reproductive technology (ART), a retrospective study of the Japanese Assisted Reproductive Technology Registry data during the years 2007-2012 was conducted.

Methods

A total of 124 946 singleton neonates who reached term gestation following ART from 2007-2012, with 80 660 achieved through frozen-thawed embryo transfer (ET) and 44 286 being achieved through fresh ET, were analyzed for their birthweights and chromosomal abnormalities.

Results

The birthweight of the neonates from the frozen-thawed ETs was significantly higher than that of those from the fresh ETs throughout all the study years. The frequency of Down syndrome was 0.17% for the fresh ETs and 0.13% for the frozen-thawed ETs in the period 2007-2012. This study showed that frozen-thawed ETs result in a constant increase of the average birthweight between 37 and 41 weeks gestational age and lower frequencies of Down syndrome.

Conclusion

Frozen-thawed ETs were comparable to the fresh ET method, with the exceptions of higher birthweights and a lower frequency of Down syndrome in the neonates that were born from frozen-thawed ET. The increase in birthweights was not proportional to the gestational ages. This cannot be explained with any well-known mechanism. The frequency of chromosomal abnormalities needs detailed data for analysis.

Assisted Reproductive Technology and Newborn Size in Singletons Resulting from Fresh and Cryopreserved Embryos Transfer

OBJECTIVES AND STUDY DESIGN

The aim of this study was two-fold: to investigate the association of Assisted Reproductive Technology (ART) and small newborn size, using standardized measures; and to examine within strata of fresh and cryopreserved embryos transfer, whether this association is influenced by parental infertility diagnoses. We used a population-based retrospective cohort from Michigan (2000-2009), Florida and Massachusetts (2000-2010). Our sample included 28,946 ART singletons conceived with non-donor oocytes and 4,263,846 non-ART singletons.

METHODS

Regression models were used to examine the association of ART and newborn size, measured as small for gestational age (SGA) and birth-weight-z-score, among four mutually exclusive infertility groups: female infertility only, male infertility only, combined female and male infertility, and unexplained infertility, stratified by fresh and cryopreserved embryos transfer.

RESULTS

We found increased SGA odds among ART singletons from fresh embryos transfer compared with non-ART singletons, with little difference by infertility source [adjusted odds-ratio for SGA among female infertility only: 1.18 (95% CI 1.10, 1.26), male infertility only: 1.20 (95% CI 1.10, 1.32), male and female infertility: 1.18 (95% CI 1.06, 1.31) and unexplained infertility: 1.24 (95% CI 1.10, 1.38)]. Conversely, ART singletons, born following cryopreserved embryos transfer, had lower SGA odds compared with non-ART singletons, with mild variation by infertility source [adjusted odds-ratio for SGA among female infertility only: 0.56 (95% CI 0.45, 0.71), male infertility only: 0.64 (95% CI 0.47, 0.86), male and female infertility: 0.52 (95% CI 0.36, 0.77) and unexplained infertility: 0.71 (95% CI 0.47, 1.06)]. Birth-weight-z-score was significantly lower for ART singletons born following fresh embryos transfer than non-ART singletons, regardless of infertility diagnoses.

Increased incidence of post-term delivery and Cesarean section after frozen-thawed embryo transfer during a hormone replacement cycle

PURPOSE

This study aimed to clarify the risks of adverse pregnancy outcomes in patients who conceive singletons after frozen embryo transfer (FET) during a hormone replacement cycle and their offspring.

METHODS

A retrospective cohort study was conducted in patients who conceived after FET, based on the Japanese-assisted reproductive technology registry for 2013. The perinatal outcomes in cases with live-born singletons achieved through natural ovulatory cycle FET (NC-FET) (n = 6287) or hormone replacement cycle FET (HRC-FET) (n = 10,235) were compared. Multiple logistic regression analyses were performed to determine the potential confounding factors.

RESULTS

The frequencies of macrosomia (1.1% in NC-FET and 1.4% in HRC-FET; P = 0.058) were comparable between patients after NC-FET and HRC-FET. The proportions of post-term delivery (0.2% in NC-FET and 1.3% in HRC-FET; P < 0.001) and Cesarean section (33.6% in NC-FET and 43.0% in HRC-FET; P < 0.001) were higher in patients after HRC-FET than in patients after NC-FET. The risks of post-term delivery (adjusted odds ratio (AOR) 5.68, 95% confidence interval (CI) 3.30-9.80) and Cesarean section (AOR 1.64, 95% CI 1.52-1.76) were also higher in patients after HRC-FET than in patients after NC-FET.

CONCLUSIONS

Patients who conceived singletons after HRC-FET were at increased risk of post-term delivery and Cesarean section compared with those who conceived after NC-FET.