Female causes of infertility are associated with higher risk of preterm birth and low birth weight: analysis of 117 401 singleton live births following IVF

Low Birth Weight is Associated with Sperm DNA Fragmentation and Assisted Reproductive Technology Outcomes in Primary Infertile Men: Results of a Cross-Sectional Study

PURPOSE

To assess the relationship between clinical and semen characteristics and assisted reproductive technology (ART) outcomes with different birth weight (BW) categories in a cohort of infertile men.

MATERIALS AND METHODS

Data from 1,063 infertile men were analyzed. Patients with BW ≤2,500, 2,500-4,000, and ≥4,000 g were considered as having low BW (LBW), normal BW (NBW), and high BW (HBW), respectively. Testicular volume (TV) was assessed with a Prader orchidometer. Serum hormones were measured in all cases. Semen analyses were categorized based on 2021 World Health Organization reference criteria. Sperm DNA fragmentation (SDF) was tested in every patient and considered pathological for SDF >30%. ART outcomes were available for 282 (26.5%) patients. Descriptive statistics and logistic regression analyses detailed the association between semen parameters and clinical characteristics and the defined BW categories.

RESULTS

Of all, LBW, NBW, and HBW categories were found in 79 (7.5%), 807 (76.0%), and 177 (16.5%) men, respectively. LBW men had smaller TV, presented higher follicle-stimulating hormone (FSH) but lower total testosterone levels compared to other groups (all p<0.01). Sperm progressive motility (p=0.01) and normal morphology (p<0.01) were lower and SDF values were higher (all p<0.01) in LBW compared to other groups. ART pregnancy outcomes were lower in LBW compared to both NBW and HBW categories (26.1% vs. 34.5% vs. 34.5%, p=0.01). At multivariable logistic regression analysis, LBW was associated with SDF >30% (odd ratio [OR] 3.7; p<0.001), after accounting for age, Charlson Comorbidity Index (CCI), FSH, and TV. Similarly, LBW (OR 2.2; p<0.001), SDF >30% (OR 2.9; p<0.001) and partner's age (OR 1.3; p=0.001) were associated with negative ART outcomes, after accounting for the same predictors.

CONCLUSIONS

LBW was associated with impaired clinical and semen characteristics in infertile men compared to both NBW and HBW. SDF and ART outcomes were significantly worse in the LBW group.

Increased risk of placenta previa and preterm birth in pregnant women with endometriosis/adenomyosis: A propensity-score matching analysis of a nationwide perinatal database in Japan

AIM

We aimed to investigate the associations of endometriosis and adenomyosis with pregnancy complications by using a large-scale Japanese database.

METHODS

We retrospectively analyzed 145 590 singleton pregnancies from the Japan Perinatal Registry Network Database. Pregnant women registered as having endometriosis or adenomyosis were designated as the case group (EA), whereas the control group (non-EA) was selected using propensity-score matching adjusted for variables such as age, parity, BMI, smoking history, and the use of assisted reproductive technology. The main outcomes included placental malposition, preterm birth, and hypertensive disorders of pregnancy (HDP).

RESULTS

In total, 1203 patients from both the EA and non-EA groups were matched and evaluated. The EA group showed significantly higher rates of placenta previa (odds ratio [OR], 3.01; 95% confidence interval [CI], 1.84-4.92), low-lying placenta (OR, 2.02; 95% CI, 1.06-3.86), and preterm birth (OR, 1.44; 95% CI, 1.13-1.84) than the non-EA group. However, no significant difference was observed in the incidence of HDP (OR, 1.22; 95% CI, 0.90-1.66).

CONCLUSION

The use of propensity-score matching to analyze a nationwide perinatal database in Japan clarified that EA was associated with increased pregnancy complications, specifically placental malposition, including placenta previa and low-lying placenta, and preterm birth, but not with HDP.

Do IVF culture conditions have an impact on neonatal outcomes? A systematic review and meta-analysis

PURPOSE

Are embryo culture conditions, including type of incubator, oxygen tension, and culture media, associated with obstetric or neonatal complications following in vitro fertilization (IVF)?

METHODS

A systematic search of MEDLINE, EMBASE, and Cochrane Library was performed from January 01, 2008, until October 31, 2021. The studies reporting quantitative data on at least one of the primary outcomes (birthweight and preterm birth) for the exposure group and the control group were included. For oxygen tension, independent meta-analysis was performed using Review Manager, comparing hypoxia/normoxia. For culture media, a network meta-analysis was carried out using R software, allowing the inclusion of articles comparing two or more culture media.

RESULTS

After reviewing 182 records, 39 full-text articles were assessed for eligibility. A total of 28 studies were kept for review. Meta-analysis about the impact of incubator type on perinatal outcomes could not be carried out because of a limited number of studies. For oxygen tension, three studies were included. The pairwise meta-analysis comparing hypoxia/normoxia did not show any statistical difference for birthweight and gestational age at birth. For culture media, 18 studies were included. The network meta-analysis failed to reveal any significant impact of different culture media on birthweight or preterm birth.

CONCLUSION

No difference was observed for neonatal outcomes according to the embryo culture conditions evaluated in this review. Further research is needed about the safety of IVF culture conditions as far as future children's health is concerned.

Children born after assisted reproduction more commonly carry a mitochondrial genotype associating with low birthweight

Children conceived through assisted reproductive technologies (ART) have an elevated risk of lower birthweight, yet the underlying cause remains unclear. Our study explores mitochondrial DNA (mtDNA) variants as contributors to birthweight differences by impacting mitochondrial function during prenatal development. We deep-sequenced the mtDNA of 451 ART and spontaneously conceived (SC) individuals, 157 mother-child pairs and 113 individual oocytes from either natural menstrual cycles or after ovarian stimulation (OS) and find that ART individuals carried a different mtDNA genotype than SC individuals, with more de novo non-synonymous variants. These variants, along with rRNA variants, correlate with lower birthweight percentiles, independent of conception mode. Their higher occurrence in ART individuals stems from de novo mutagenesis associated with maternal aging and OS-induced oocyte cohort size. Future research will establish the long-term health consequences of these changes and how these findings will impact the clinical practice and patient counselling in the future.

Obstetric and perinatal outcomes after embryos cultured in one-step versus sequential culture media systems in vitrified-warmed single blastocyst transfer cycles

RESEARCH QUESTION

Does type of culture medium used influence obstetric and perinatal outcomes after vitrified-warmed single blastocyst transfers?

DESIGN

Retrospective cohort study involving singletons after vitrified-warmed single blastocyst embryo transfers, using embryos cultured in either Irvine Continuous Single Culture medium (CSC) or Vitrolife G5TM PLUS medium culture system between 2013 and 2020.

RESULTS

A total of 2475 women who had singleton deliveries were included for final analysis: 1478 had embryos cultured in CSC and 997 had embryos cultured in G5TM PLUS medium. Birth outcomes, including preterm birth, mean birth weight, gestational age- and sex-adjusted birth weight (Z-scores), rates of large-for-gestational-age, small-for-gestational-age, low birth weight and macrosomia, and the distribution of newborn gender did not differ significantly between groups in crude and adjusted analyses. Women whose embryos were cultured in G5TM PLUS frequently suffered from pregnancy-induced hypertensive disorders compared with those who had embryos cultured in CSC (4.7% versus 3.0%; P = 0.031). This difference was no longer significant after adjusting for several key confounders (adjusted odds ratio 1.49, 95% CI 0.94 to 2.38, P = 0.087). Other obstetric complications, including gestational diabetes mellitus, preterm premature rupture of membranes, abnormal placentation, postpartum haemorrhage and the mode of delivery were all similar between the two groups.

CONCLUSIONS

The present study adds new information to the current evidence by suggesting that the embryo culture medium does not affect birth outcomes and obstetric complications when comparison is limited to Irvine CSC and Vitrolife G5TM PLUS in vitrified-warmed single blastocyst transfer cycles.

Long-Term Effects of ART on the Health of the Offspring

Assisted reproductive technologies (ART) significantly increase the chance of successful pregnancy and live birth in infertile couples. The different procedures for ART, including in vitro fertilization (IVF), intracytoplasmic sperm injection (ICSI), intrauterine insemination (IUI), and gamete intrafallopian tube transfer (GIFT), are widely used to overcome infertility-related problems. In spite of its inarguable usefulness, concerns about the health consequences of ART-conceived babies have been raised. There are reports about the association of ART with birth defects and health complications, e.g., malignancies, high blood pressure, generalized vascular functional disorders, asthma and metabolic disorders in later life. It has been suggested that hormonal treatment of the mother, and the artificial environment during the manipulation of gametes and embryos may cause genomic and epigenetic alterations and subsequent complications in the health status of ART-conceived babies. In the current study, we aimed to review the possible long-term consequences of different ART procedures on the subsequent health status of ART-conceived offspring, considering the confounding factors that might account for/contribute to the long-term consequences.

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.

The effect of the day 3 embryo cell number on the neonatal outcomes of day 5 single blastocyst transfer in frozen embryo transfer cycles

OBJECTIVE

To evaluate the influence of the day 3 embryo cell number on the neonatal outcomes of day 5 single blastocyst transfer in frozen embryo transfer (FET) cycles.

METHODS

This retrospective study analysed a total of 2315 delivery cycles of day 5 single blastocyst transfer in FET cycles, including 489, 761 and 1103 live-born infants segregated according to a day 3 embryo cell number of <8, 8 and >8 cells, respectively. The neonatal outcomes of the three groups were compared.

RESULTS

The day 3 embryo cell number did not significantly affect the incidence of monozygotic twins. The sex ratio increased as the day 3 embryo cell number increased, but the difference was not statistically significant. There were no significant differences in the rates of preterm birth or low birth weight among the three groups. The rates of stillbirths and neonatal deaths were also not significantly different among the three groups. Moreover, the day 3 embryo cell number did not increase the risk of birth defects in newborns.

CONCLUSIONS

The day 3 embryo cell number did not significantly affect neonatal outcomes.

Associations of Preterm Birth with Dental and Gastrointestinal Diseases: Machine Learning Analysis Using National Health Insurance Data

BACKGROUND

This study uses machine learning with large-scale population data to assess the associations of preterm birth (PTB) with dental and gastrointestinal diseases.

METHODS

Population-based retrospective cohort data came from Korea National Health Insurance claims for 124,606 primiparous women aged 25-40 and delivered in 2017. The 186 independent variables included demographic/socioeconomic determinants, disease information, and medication history. Machine learning analysis was used to establish the prediction model of PTB. Random forest variable importance was used for identifying major determinants of PTB and testing its associations with dental and gastrointestinal diseases, medication history, and socioeconomic status.

RESULTS

The random forest with oversampling data registered an accuracy of 84.03, and the areas under the receiver-operating-characteristic curves with the range of 84.03-84.04. Based on random forest variable importance with oversampling data, PTB has strong associations with socioeconomic status (0.284), age (0.214), year 2014 gastroesophageal reflux disease (GERD) (0.026), year 2015 GERD (0.026), year 2013 GERD (0.024), progesterone (0.024), year 2012 GERD (0.023), year 2011 GERD (0.021), tricyclic antidepressant (0.020) and year 2016 infertility (0.019). For example, the accuracy of the model will decrease by 28.4%, 2.6%, or 1.9% if the values of socioeconomic status, year 2014 GERD, or year 2016 infertility are randomly permutated (or shuffled).

CONCLUSION

By using machine learning, we established a valid prediction model for PTB. PTB has strong associations with GERD and infertility. Pregnant women need close surveillance for gastrointestinal and obstetric risks at the same time.

Fetal growth disorders following medically assisted reproduction: due to maternal context or techniques? A national French cohort study

RESEARCH QUESTION

What part do maternal context and medically assisted reproduction (MAR) techniques play in the risk of fetal growth disorders?

DESIGN

This retrospective nationwide cohort study uses data available in the French National Health System database and focuses on the period from 2013 to 2017. Fetal growth disorders were divided into four groups according to the origin of pregnancy: fresh embryo transfer (n = 45,201), frozen embryo transfer (FET, n = 18,845), intrauterine insemination (IUI, n = 20,179) and natural conceptions (n = 3,412,868). Fetal growth disorders were defined from the percentiles of the weight distribution according to gestational age and sex: small and large for gestational age (SGA and LGA) if <10th and >90th percentiles, respectively. Analyses were performed using univariate and multivariate logistic models.

RESULTS

Compared with births following natural conception, multivariate analysis showed that the risk of SGA was higher for births following fresh embryo transfer and IUI (adjusted odds ratio [aOR] 1.26 [1.22-1.29] and 1.08 [1.03-1.12], respectively) and significantly lower following FET (aOR 0.79 [0.75-0.83]). The risk of LGA was higher for births following FET (aOR 1.32 [1.27-1.38]), especially in artificial cycles when compared with ovulatory cycles (aOR 1.25 [1.15-1.36]). In the subgroup of births without any obstetrical or neonatal morbidity, the same increased risk of SGA and LGA were observed following fresh embryo transfer or IUI and FET (aOR 1.23 [1.19-1.27] or 1.06 [1.01-1.11] and aOR 1.36 [1.30-1.43], respectively).

CONCLUSIONS

An effect of MAR techniques on the risks for SGA and LGA is suggested independently from maternal context and obstetrical or neonatal morbidities. Pathophysiological mechanisms remain poorly understood and should be further evaluated, as well as the influence of embryonic stage and freezing techniques.

The impact of maternal ABO blood type on obstetric and perinatal outcomes after frozen embryo transfer

RESEARCH QUESTION

Does the maternal ABO blood type affect obstetric and perinatal outcomes following frozen embryo transfer (FET)?

DESIGN

A retrospective study was performed at a university-affiliated fertility centre, involving women with singleton and twin deliveries conceived by FET. Subjects were divided into four groups based on ABO blood type. The primary end-points were obstetric and perinatal outcomes.

RESULTS

A total of 20,981 women were involved, with 15,830 having singletons and 5151 delivering twins. In singleton pregnancies, women with blood group B had a slight but significantly increased risk of gestational diabetes mellitus compared to women with blood group O (adjusted odds ratio [aOR] 1.16; 95% confidence interval [CI] 1.01-1.34). Furthermore, singletons born to women with the B antigen (blood type B or AB) were more likely to be large for gestational age (LGA) and with macrosomia. In twin pregnancies, blood type AB was related to a decreased risk of hypertensive diseases of pregnancy (aOR 0.58; 95% CI 0.37-0.92), while blood type A was associated with a higher risk of placenta praevia (aOR 2.04; 95% CI 1.15-3.60). When compared with the O blood group, twins from the AB blood group had a lower risk of low birthweight (aOR 0.83; 95% CI 0.71-0.98) but a higher risk of LGA (aOR 1.26; 95% CI 1.05-1.52).

CONCLUSIONS

This study demonstrates that the ABO blood group may influence the obstetric and perinatal outcomes for both singletons and twins. These findings emphasize that patient characteristics could be, at least partly, responsible for adverse maternal and birth outcomes following IVF.

Association of phthalate exposure with low birth weight in couples conceiving naturally or via assisted reproductive technology in a prospective birth cohort

BACKGROUND

Few studies have investigated the adverse effects of preconception phthalate (PAE) exposure on birth weight in couples receiving assisted reproductive technology (ART) compared to naturally conceived newborns.

OBJECTIVES

We examined the association between parental preconception/prenatal urinary phthalate exposure and low birth weight (LBW) risk in couples who conceived using ART or naturally.

METHODS

From the Jiangsu Birth Cohort Study (China), we recruited 544 couples who conceived after infertility treatment and 940 couples who conceived naturally and gave birth to a singleton infant between November 2014 and December 2019. Seventeen metabolites of phthalate and three metabolites of phthalate alternatives were analyzed in parental spot urine samples. Clinical data were collected from medical records. We used generalized linear models, elastic net regression, Bayesian kernel machine regression, and quantile-based g-computation to examine the individual and joint effects of parental phthalate exposure on birth weight and LBW risk ratios (RR).

RESULTS

The relationship between parental phthalate exposure and birth weight was consistent between ART and natural conception. Maternal exposure to mono-ethyl phthalate and mono-carboxyisooctyl phthalate was associated with an increased risk of LBW in ART-conceived infants (RR = 1.27; 95 % confidence interval (CI): 1.03, 1.56; and RR = 1.31; 95 % CI: 1.03, 1.67, respectively). In contrast, in the spontaneously conceived infants, higher paternal prenatal concentrations of mono-benzyl phthalate and mono-carboxyisononyl phthalate were associated with a 40 % and 53 % increase in LBW risk, respectively. Exposure to PAE mixtures was associated with LBW in ART-conceived infants, with the effects primarily driven by di-ethyl phthalate, benzylbutyl phthalate, and di-isononyl phthalate metabolites. Sex-specific LBW was observed, with females appearing to be more susceptible than males.

CONCLUSIONS

Maternal preconception and paternal prenatal exposure to phthalates were associated with increased risk of LBW in infants. Compared with natural conception, ART-conceived fetuses were more sensitive to PAE mixtures, which requires further attention.

Perinatal outcomes of 221,709 singleton and twin pregnancies after the use of donor versus partner sperm

OBJECTIVE

To study the association of donor sperm on perinatal outcomes of livebirths conceived via in vitro fertilization (IVF) when compared with partner sperm.

DESIGN

Retrospective cohort study SETTING: National Human Fertilisation and Embryology Authority assisted reproductive technology registry PATIENTS: All live born singletons and twins conceived through IVF with or without intracytoplasmic sperm injection in the United Kingdom between 1991 and 2016 INTERVENTION(S): Donor sperm compared to partner sperm MAIN OUTCOME MEASURE(S): Perinatal outcomes were assessed. The primary outcomes were preterm and very preterm birth; low, very low, high, and very high birthweight; Secondary outcomes were congenital anomaly and health baby. These were assessed for singletons and twins separately.

RESULTS

For singleton livebirths, compared to partner sperm, those conceived with donor sperm were at reduced odds of very preterm (odds ratio [OR], 0.76; 95% confidence interval [CI], 0.63-0.91; adjusted OR [aOR], 0.80; 95% CI, 0.66-0.96), and preterm (OR, 0.90; 95% CI, 0.83-0.98; aOR, 0.93; 95% CI, 0.85-1.01) birth. For birthweight outcomes, donor sperm showed a reduced odds of low (OR, 0.83; 95% CI, 0.76-0.91; aOR, 0.86; 95% CI, 0.78-0.94) and an increased odds of high (OR, 1.15; 95% CI, 1.07-1.23; aOR, 1.09; 95% CI, 1.01-1.17) birthweight. There was no confirmed difference in the odds ratios of very low (OR, 0.88; 95% CI, 0.74-1.06; aOR, 0.94; 95% CI, 0.78-1.13) or very high (OR, 1.21; 95% CI, 1.04-1.40; aOR, 1.15; 95% CI, 0.98-1.34) birthweight. Liveborn twins conceived with donor sperm, compared to partner sperm, were at reduced odds of very low (OR, 0.76; 95% CI, 0.66-0.88; aOR, 0.83; 95% CI, 0.72-0.96) and low (OR, 0.87; 95% CI, 0.81-0.93; aOR, 0.91; 95% CI, 0.85-0.98) birthweight. There was a suggestion of a reduced odds of very preterm (OR, 0.81; 95% CI, 0.70-0.95; aOR, 0.86; 95% CI, 0.74-1.01) and preterm (OR, 0.93; 95% CI, 0.86-1.01; aOR, 0.96; 95% CI, 0.88-1.04) birth. There was considerable uncertainty around the ORs for high (OR, 0.73; 95% CI, 0.31-1.72; aOR, 0.72; 95% CI, 0.29-1.80) and very high (OR, 1.02; 95% CI, 0.39-2.67; aOR, 1.34; 95% CI, 0.50-3.60) birthweight.

CONCLUSION

Although unmeasured confounding remains a possibility, as paternal age, body mass index, and smoking status were unavailable for analysis, women, couples, service providers can be reassured that IVF livebirths conceived with donor sperm have no greater chance of adverse outcomes when compared to partner sperm.

Endometriosis and oocyte quality: an analysis of 13 614 donor oocyte recipient and autologous IVF cycles

STUDY QUESTION

Does endometriosis affect live birth following donor oocyte recipient versus autologous IVF?

SUMMARY ANSWER

There was no significant difference in the live birth rate (LBR) in women with endometriosis undergoing donor oocyte recipient cycles versus autologous IVF cycles.

WHAT IS KNOWN ALREADY

For infertile women with endometriosis, IVF is often considered as a treatment option. Lower implantation and pregnancy rates have been observed following IVF in women with endometriosis. It has been debated whether the lower pregnancy rate is due to the effect on oocyte quality or the endometrium, thus affecting implantation. To delineate whether endometriosis affects oocyte quality or the endometrium, we planned a study, using a donor oocyte recipient model, where the recipients were women diagnosed with endometriosis and compared their outcomes with women who underwent autologous IVF, who had also been diagnosed with endometriosis.

STUDY DESIGN, SIZE, DURATION

Human Fertilization and Embryology Authority (HFEA) anonymized data from 1996 to 2016 were analyzed. This comprised of a total of 758 donor oocyte recipients, where the recipients were women diagnosed with endometriosis, and 12 856 autologous IVF cycles where the women were diagnosed with endometriosis as the sole cause of infertility.

PARTICIPANTS/MATERIALS, SETTING, METHODS

Data on all women with endometriosis undergoing donor oocyte recipient and autologous IVF cycles were analyzed to compare live birth outcomes. Logistic regression analysis was performed adjusting for number of previous IVF cycles, previous live birth, period of treatment, day of embryo transfer, number of embryos transferred and fresh or frozen embryo transfer cycle.

MAIN RESULTS AND THE ROLE OF CHANCE

There was no significant difference in the LBR in women with endometriosis undergoing donor oocyte recipient fresh embryo transfer cycles compared to women undergoing autologous IVF fresh embryo transfer cycles (31.6% vs 31.0%; odds ratio (OR) 1.03, 99.5% CI 0.79–1.35). After adjusting for confounders, there was no significant difference in LBR in women with endometriosis undergoing donor oocyte recipient fresh embryo transfer cycles versus autologous fresh embryo transfer cycles (adjusted OR (aOR) 1.05, 99.5% CI 0.79–1.41).

There was no significant difference in the LBR in women with endometriosis undergoing donor oocyte recipient frozen embryo transfer cycles compared to women undergoing autologous frozen embryo transfer cycles (19.6% vs 24.0%; OR 0.77, 99.5% CI 0.47–1.25). After adjusting for potential confounders, there was no significant difference in the LBR in women undergoing donor oocyte recipient frozen embryo transfer cycles compared with autologous frozen embryo transfer cycles (aOR 0.85, 99.5% CI 0.51–1.41).

LIMITATIONS, REASONS FOR CAUTION

Although the analysis was adjusted for potential confounders, there was no information on the extent and classification of endometriosis as well as oocyte number. Furthermore, adenomyosis is thought to co-exist in women with endometriosis and may have independent pathophysiological mechanisms affecting fertility, for which there was no information.

WIDER IMPLICATIONS OF THE FINDINGS

The study shows no difference in LBR between donor oocyte recipient cycles in which all recipients had endometriosis compared to autologous IVF cycles in women with endometriosis. Therefore, this study finding suggests that there may be a minimal or no effect of oocyte quality on IVF outcomes in women with endometriosis.

STUDY FUNDING/COMPETING INTEREST(S)

No funding was obtained. M.S.K. is an associate editor with Human Reproduction Open. He was not involved in the editorial or peer review process for the manuscript.

TRIAL REGISTRATION NUMBER

N/A.

Epigenetic Risks of Medically Assisted Reproduction

Since the birth of Louise Joy Brown, the first baby conceived via in vitro fertilization, more than 9 million children have been born worldwide using assisted reproductive technologies (ART). In vivo fertilization takes place in the maternal oviduct, where the unique physiological conditions guarantee the healthy development of the embryo. During early embryogenesis, a major wave of epigenetic reprogramming takes place that is crucial for the correct development of the embryo. Epigenetic reprogramming is susceptible to environmental changes and non-physiological conditions such as those applied during in vitro culture, including shift in pH and temperature, oxygen tension, controlled ovarian stimulation, intracytoplasmic sperm injection, as well as preimplantation embryo manipulations for genetic testing. In the last decade, concerns were raised of a possible link between ART and increased incidence of imprinting disorders, as well as epigenetic alterations in the germ cells of infertile parents that are transmitted to the offspring following ART. The aim of this review was to present evidence from the literature regarding epigenetic errors linked to assisted reproduction treatments and their consequences on the conceived children. Furthermore, we provide an overview of disease risk associated with epigenetic or imprinting alterations in children born via ART.

Association of adverse birth outcomes with in vitro fertilization after controlling infertility factors based on a singleton live birth cohort

Infants conceived with in vitro fertilization (IVF) are exposed to underlying infertility and the IVF process. High risks of adverse birth outcomes (ABOs) were observed among these infants, including preterm birth, low birth weight, macrosomia, being large/small for gestational age (LGA/SGA). It is unclear whether the specific etiology of the rise of ABOs among IVF infants is IVF technology itself or underlying infertility. A total of 9,480 singletons conceived with IVF and 1,952,419 singletons from the general population were obtained in this study. Multivariable logistic regression model was used to assess variations in risk of ABOs according to causes of infertility. Poisson distributions were applied to calculate standardized risk ratios of IVF infants vs. general population after controlling the causes of infertility. Higher risk of preterm birth and low birth weight were observed among parents with polycystic ovary syndrome, endometriosis, uterine and semen abnormalities. Compared to the general population, after excluding the influence of infertility causes, singletons conceived with IVF were at higher risk of macrosomia (SRR = 1.28, 95% CI 1.14-1.44) and LGA (SRR = 1.25, 95% CI 1.15-1.35). The higher risk of ABOs in IVF was driven by both IVF treatments and infertility, which is important for improving IVF treatments and the managing pregnancies and child development.

Assisted Reproductive Technology Treatment, the Catalyst to Amplify the Effect of Maternal Infertility on Preterm Birth

OBJECTIVE

To identify the influence of different infertility causes and assisted reproductive technology (ART) treatment on perinatal outcomes and clarify the relationship between the maternal pathophysiological changes and artificial interventions.

METHODS

A total of 1,629 fertile women and 27,112 infertile women with sole infertility causes were prospectively recruited from July 2014 to December 2017, and 9,894 singletons were finally enrolled into the study. Pregnancies with more than one cause of infertility and/or multiple births were excluded. According to the causes of infertility and the exposure of ART treatment, the participants were divided into four groups, namely, fertile naturally conceived (NC) group, infertile NC group, female factor ART group, and male factor ART group. Perinatal outcomes, including gestational age of delivery (GA), birth weight (BW), preterm birth (PTB), low birth weight (LBW), small for gestational age (SGA), and large for gestational age (LGA), were compared among groups. Logistic regression was performed for the adjustment of several covariates.

RESULTS

The birth outcomes of the infertile NC group and fertile NC group, female factor ART group, and infertile NC group were comparable. Compared to the fertile NC group, the female factor ART group had a shorter GA (39.0 ± 1.6 vs. 39.3 ± 1.5 weeks, BW: P < 0.05). An interaction test showed that ART treatment had an interaction on the effect of female infertility on GA (P = 0.023). The female factor ART group also had a higher risk of PTB (OR 1.56, 95% CI 1.18-2.07) and LGA (OR 1.27, 95% CI 1.10-1.47) compared to the fertile NC group. The risk of PTB was increased for tubal factor ART (OR 1.49, 95% CI 1.12-2.00), ovulatory dysfunction ART (OR 1.87, 95% CI 1.29-2.72), and unexplained infertility ART (OR 1.88, 95% CI 1.11-3.17). The risk of LGA was increased for tubal factor ART (OR 1.28, 95% CI 1.11-1.48) and ovulatory dysfunction ART (OR 1.27, 95% CI 1.03-1.57).

CONCLUSIONS

Our findings indicated that ART treatment could amplify the adverse effect of female infertility on neonates. Women with tubal factor infertility, ovulatory dysfunction, and unexplained infertility have a higher risk of PTB after ART treatment. Thus, clinicians should be vigilant in such patients and provide corresponding prevention strategies before and during pregnancy.

"Double Frozen Transfer" Could Influence the Perinatal and Children's Growth: A Nested Case-Control Study of 6705 Live Birth Cycles

OBJECTIVE

This study aims to evaluate neonatal and children growth outcomes of cryotransfer of embryos developed from frozen gametes [double frozen transfer (DFT)].

METHODS

This nested case-control study included 6,705 women who had a singleton live birth after embryo transfer at the Center for Reproductive Medicine, Shandong University, from 2008 to 2020. Of these, 745 women underwent frozen embryo transfer (FET) using embryos developed from frozen gametes (DFT). Propensity score methodology was used to balance the two groups by maternal age and body mass index (BMI) before evaluating outcomes. After age and BMI were matched using the propensity score methodology in a ratio of 1:4, the control groups enrolled 2,980 women who underwent fresh embryo transfer (ET) and 2,980 women underwent FET from fresh gametes. The children born were followed to at least 5 years of age, and some were followed up to 10 years. Neonatal outcomes and childhood growth measurements were compared among the three groups.

RESULTS

The average birth weight of the DFT group (3,462 g) was significantly higher than the FET group (3,458 g) and ET group (3,412 g). The rate of large for gestational age (LGA) babies in the DFT and FET group was higher than that for the ET group (30.9% vs. 24.8%; 29.4% vs. 24.8%, respectively). After adjusting for different confounder combinations in the three models, the birth weight and risk of LGA in the DFT and FET groups were still higher than in the ET group, and the values group of P for trend in the models were significant. In multiple linear regression analysis of the children's development, the height Z-score of children born from the DFT and FET group was higher than that for children from the ET group (β = 0.21, 95% CI 0.07-0.35; b = 0.17, 95% CI 0.05-0.28, respectively). However, childhood growth measurements including body weight Z-score and BMI Z-score were not significantly different among the three groups. In addition, the proportion of male children born from DET was higher than that from ET.

CONCLUSIONS

There is an increased risk of LGA babies associated with pregnancies conceived from DFT. Children are inclined to be taller in the future in this group than after FET. The related etiology and pathophysiology mechanisms still need to be revealed. In the future, well-designed, observational studies with in-depth collection of patients' characteristics may shed more light on this issue.

Endometriosis and Risk of Adverse Pregnancy Outcome: A Systematic Review and Meta-Analysis

Background: This systematic review and meta-analysis summarizes the evidence for the association between endometriosis and adverse pregnancy outcome, including gestational hypertension, pre-eclampsia, low birth weight, and small for gestational age, preterm birth, placenta previa, placental abruption, cesarean section, stillbirth, postpartum hemorrhage, spontaneous hemoperitoneum in pregnancy, and spontaneous bowel perforation in pregnancy. Methods: We performed the literature review in accordance with Preferred Reporting Items for Systematic Reviews and Meta-Analysis (PRISMA), by searches in PubMed and EMBASE, until 1 November 2020 (PROSPERO ID CRD42020213999). We included peer-reviewed observational cohort studies and case-control studies and scored them according to the Newcastle–Ottawa Scale, to assess the risk of bias and confounding. Results: 39 studies were included. Women with endometriosis had an increased risk of gestational hypertension, pre-eclampsia, preterm birth, placenta previa, placental abruption, cesarean section, and stillbirth, compared to women without endometriosis. These results remained unchanged in sub-analyses, including studies on spontaneous pregnancies only. Spontaneous hemoperitoneum in pregnancy and bowel perforation seemed to be associated with endometriosis; however, the studies were few and did not meet the inclusion criteria. Conclusions: The literature shows that endometriosis is associated with an increased risk of gestational hypertension, pre-eclampsia, preterm birth, placenta previa, placental abruption, cesarean section, and stillbirth.