No effect of embryo culture media on birthweight and length of newborns

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.

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.

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.

Obstetric and neonatal outcomes of pregnancies resulting from preimplantation genetic testing: a systematic review and meta-analysis

BACKGROUND

Preimplantation genetic testing (PGT) includes methods that allow embryos to be tested for severe inherited diseases or chromosomal abnormalities. In addition to IVF/ICSI and repeated freezing and thawing of the embryos, PGT requires a biopsy to obtain embryonic genetic material for analysis. However, the potential effects of PGT on obstetric and neonatal outcomes are currently uncertain.

OBJECTIVE AND RATIONALE

This study aimed to investigate whether pregnancies conceived after PGT were associated with a higher risk of adverse obstetric and neonatal outcomes compared with spontaneously conceived (SC) pregnancies or pregnancies conceived after IVF/ICSI.

SEARCH METHODS

PubMed, EMBASE, MEDLINE, Web of Science and The Cochrane Library entries from January 1990 to January 2021 were searched. The primary outcomes in this study were low birth weight (LBW) and congenital malformations (CMs), and the secondary outcomes included gestational age, preterm delivery (PTD), very preterm delivery (VPTD), birth weight (BW), very low birth weight (VLBW), neonatal intensive care unit (NICU) admission, hypertensive disorders of pregnancy (HDP), gestational diabetes, placenta previa and preterm premature rupture of membranes (PROM). We further pooled the results of PGT singleton pregnancies. Subgroup analyses included preimplantation genetic diagnosis (PGD), preimplantation genetic screening (PGS), cleavage-stage biopsy combined with fresh embryo transfer (CB-ET) and blastocyst biopsy combined with frozen-thawed embryo transfer (BB-FET).

OUTCOMES

This meta-analysis included 15 studies involving 3682 babies born from PGT pregnancies, 127 719 babies born from IVF/ICSI pregnancies and 915 222 babies born from SC pregnancies. The relative risk (RR) of LBW was higher in PGT pregnancies compared with SC pregnancies (RR = 3.95, 95% confidence interval [CI]: 2.32-6.72), but the risk of CMs was not different between the two groups. The pooled results for the risks of LBW and CMs were similar in PGT and IVF/ICSI pregnancies. The risks of PTD (RR = 3.12, 95% CI: 2.67-3.64) and HDP (RR = 3.12, 95% CI: 2.18-4.47) were significantly higher in PGT pregnancies compared with SC pregnancies. Lower gestational age (mean difference [MD] = -0.76 weeks, 95% CI -1.17 to -0.34) and BW (MD = -163.80 g, 95% CI: -299.35 to -28.24) were also noted for PGT pregnancies compared with SC pregnancies. Nevertheless, compared with IVF/ICSI pregnancies, the risks of VPTD and VLBW in PGT pregnancies were significantly decreased by 41% and 30%, respectively, although the risk of HDP was still significantly increased by 50% in PGT pregnancies compared with IVF/ICSI pregnancies. The combined results of obstetric and neonatal outcomes of PGT and IVF/ICSI singleton pregnancies were consistent with the overall results. Further subgroup analyses indicated that both PGD and PGS pregnancies were associated with a higher risk of PTD and a lower gestational age compared with SC pregnancies.

WIDER IMPLICATIONS

This meta-analysis showed that PGT pregnancies may be associated with increased risks of LBW, PTD and HDP compared with SC pregnancies. The overall obstetric and neonatal outcomes of PGT pregnancies are favourable compared with those of IVF/ICSI pregnancies, although PGT pregnancies were associated with a higher risk of HDP. However, because the number of studies that could be included was limited, more randomised controlled trials and prospective cohort studies are needed to confirm these conclusions.

Embryo Culture Media Influence on Live Birth Rate and Birthweight after IVF/ICSI: A Systematic Review Comparing Vitrolife G5 Media to Other Common Culture Media

Previous studies have indicated that culture media vary in efficiency and outcomes, such as live birth rate, birthweight and embryo quality. Does Vitrolife G5 series culture media result in higher live birth rates and birthweight compared to other common culture media? This study is a systematic review based on the PRISMA criteria. Relevant search terms, mesh terms (PubMed and Cochrane) and Emtree terms (Embase) were identified. We searched the literature using PubMed, Embase and Cochrane, on November 10, 2019. The inclusion criteria involved published articles in English comparing Vitrolife G5 to other common culture media. We included randomized controlled trials (RCTs) and cohort studies. The quality of the studies was assessed using the Cochrane Risk of Bias tool 2.0 and the Newcastle-Ottawa Scale. Primary outcomes were live birth rate and birthweight. Secondary outcomes were fertilization rate, implantation rate, biochemical pregnancy rate, clinical pregnancy rate, miscarriage rate, multiple pregnancies and congenital malformations. Of 187 articles screened, 11 studies fulfilled the inclusion criteria: Five RCTs and six retrospective cohort studies. Only one study reported live birth rate, showing a non-significantly higher live birth rate for Vitrolife G5 media. Birthweight had equivocal results with three of six studies, showing significantly lower (2)/higher (1) birthweights, whereas the others were non-significant. Overall, there were no significant differences concerning secondary outcomes. The results are equivocal, and we need more studies to evaluate culture media and their effect on short- and long-term health.

Comparison of DNA methylation patterns of parentally imprinted genes in placenta derived from IVF conceptions in two different culture media

Study question

Is there a difference in DNA methylation status of imprinted genes in placentas derived from IVF conceptions where embryo culture was performed in human tubal fluid (HTF) versus G5 culture medium?

Summary answer

We found no statistically significant differences in the mean DNA methylation status of differentially methylated regions (DMRs) associated with parentally imprinted genes in placentas derived from IVF conceptions cultured in HTF versus G5 culture medium.

What is known already

Animal studies indicate that the embryo culture environment affects the DNA methylation status of the embryo. In humans, birthweight is known to be affected by the type of embryo culture medium used. The effect of embryo culture media on pregnancy, birth and child development may thus be mediated by differential methylation of parentally imprinted genes in the placenta.

Study design, size, duration

To identify differential DNA methylation of imprinted genes in human placenta derived from IVF conceptions exposed to HTF or G5 embryo culture medium, placenta samples (n = 43 for HTF, n = 54 for G5) were collected between 2010 and 2012 s as part of a multi-center randomized controlled trial in the Netherlands comparing these embryo culture media. Placenta samples from 69 naturally conceived (NC) live births were collected during 2008–2013 in the Netherlands as reference material.

Participants/materials, setting, methods

To identify differential DNA methylation of imprinted genes, we opted for an amplicon-based sequencing strategy on an Illumina MiSeq sequencing platform. DNA was isolated and 34 DMRs associated with well-defined parentally imprinted genes were amplified in a two-step PCR before sequencing using MiSeq technology. Sequencing data were analyzed in a multivariate fashion to eliminate possible confounding effects.

Main results and the role of chance

We found no statistically significant differences in the mean DNA methylation status of any of the imprinted DMRs in placentas derived from IVF conceptions cultured in HTF or G5 culture medium. We also did not observe any differences in the mean methylation status per amplicon nor in the variance in methylation per amplicon between the two culture medium

groups. A separate surrogate variable analysis also demonstrated that the IVF culture medium was not associated with the DNA methylation status of these DMRs. The mean methylation level and variance per CpG was equal between HTF and G5 placenta. Additional comparison of DNA methylation status of NC placenta samples revealed no statistically significant differences in mean amplicon and CpG methylation between G5, HTF and NC placenta; however, the number of placenta samples exhibiting outlier methylation levels was higher in IVF placenta compared to NC (P < 0.00001). Also, we were able to identify 37 CpG sites that uniquely displayed outlier methylation in G5 placentas and 32 CpG sites that uniquely displayed outlier methylation in HTF. In 8/37 (G5) and 4/32 (HTF) unique outliers CpGs, a medium-specific unique outlier could be directly correlated to outlier methylation of the entire amplicon.

Limitations, reasons for caution

Due to practical reasons, not all placentas were collected during the trial, and we collected the placentas from natural conceptions from a different cohort, potentially creating bias. We limited ourselves to the DNA methylation status of 34 imprinted DMRs, and we studied only the placenta and no other embryo-derived tissues.

Wider implications of the findings

It has often been postulated, but has yet to be rigorously tested, that imprinting mediates the effects of embryo culture conditions on pregnancy, birth and child development in humans. Since we did not detect any statistically significant effects of embryo culture conditions on methylation status of imprinted genes in the placenta, this suggests that other unexplored mechanisms may underlie these effects. The biological and clinical relevance of detected outliers with respect to methylation levels of CpGs and DMR require additional analysis in a larger sample size as well. Given the importance and the growing number of children born through IVF, research into these molecular mechanisms is urgently needed.

Study funding/competing interest(s)

This study was funded by the March of Dimes grant number #6-FY13-153. The authors have no conflicts of interest.

Trial registration number

Placental biopsies were obtained under Netherlands Trial Registry number 1979 and 1298.

Perinatal outcomes in singleton pregnancies after in vitro fertilization cycles over 24 years

OBJECTIVE

To determine how a shift in clinical practice along with laboratory changes has impacted singleton perinatal outcomes after autologous in vitro fertilization (IVF) cycles.

DESIGN

Retrospective cohort.

SETTING

Single academic fertility clinic.

PATIENT(S)

Singleton live births resulting from all IVF cycles (n = 14,424) from August 1, 1995 to October 31, 2019.

INTERVENTION(S)

None.

MAIN OUTCOME MEASURE(S)

Live birth weight, large for gestational age (GA), small for GA, and preterm birth.

RESULT(S)

The entire cohort consisted of 9,280 fresh and 5,144 frozen IVF cycles. Maternal age, parity, body mass index, neonatal sex, and GA at delivery were similar in both groups. There was a decrease in adjusted birth weight per year over the study period for the entire cohort of IVF cycles (-4.42g, 95% confidence interval [CI]: -6.63g to -2.22g). Rates of large for GA newborns decreased by 1.7% (95% CI: 2.9% to 0.6%) annually across the entire cohort of IVF cycles. Furthermore, there was a decrease in annual rates of preterm birth before 32 weeks by 3.2% (95% CI: 5.9% to 0.5%) across the entire cohort of IVF cycles. Trends were also seen in annual reduction of rates of preterm birth before 37 and 28 weeks.

CONCLUSION(S)

With the gradual evolution of clinical and IVF laboratory practices, there has been a decrease in birth weight over 24 years for the entire cohort of IVF cycles. Concurrently, noteworthy practice changes have resulted in an improvement in IVF outcomes with decreased rates of large for GA newborns and preterm birth before 32 weeks for the entire cohort of IVF cycles.

Increased maternal serum hCG concentrations in the presence of a female fetus as early as 2 weeks after IVF-ET

BACKGROUND

Maternal serum human chorionic gonadotropin (hCG) is produced in trophoblast cells during pregnancy. Whether there are sex-related growth differences of hCG concentrations in early pregnancy is still controversial.

OBJECTIVE

To explore the association between hCG concentrations and fetal sex as early as 2 weeks after in vitro fertilization and embryo transfer (IVF-ET).

METHODS

This study involved 6669 women ≤ 38 years of age. These 6669 patients all delivered singletons; 3531 had a male fetus and 3138 had a female fetus. The maternal serum hCG concentrations on Day 14 and Day 21 were determined using a Beckman DxI800 immunoassay system.

RESULTS

Among the 6669 patients who delivered singletons, 3531 had a male fetus and 3138 had a female fetus. The hCG concentrations on day 14 of gestation were 516.12 (342.12-757.34) IU/L in the group of male fetuses and 552.69 (359.35-772.83) IU/L in group of female fetuses. The hCG concentration on day 21 was 8839.60 (5975.00-12615.00) IU/L in male fetuses and 9289.10 (6162.00-13146.00) IU/L in female fetuses. Maternal serum hCG levels were significantly higher in those with female fetuses than those with male fetuses. After adjusting for confounding factors, the hCG levels were significantly associated with fetal sex.

CONCLUSIONS

Our results showed pregnant women with female fetuses have significantly higher hCG levels than those bearing male fetuses.

Randomized study of G-TL and global media for blastocyst culture in the EmbryoScope: morphokinetics, pregnancy, and live births after single-embryo transfer

OBJECTIVE

To evaluate the efficacy of two different in vitro fertilization culture media for blastocyst development, pregnancy, and live birth rate. Global (GB) medium (used without refreshment) and G-TL medium (designed specifically for culture in time-lapse incubators) were compared.

DESIGN

Prospective randomized study of sibling embryo culture in two culture media.

SETTING

In vitro fertilization clinic.

PATIENT(S)

Women undergoing fresh or frozen cycles using autologous or donor oocytes.

INTERVENTION(S)

None.

MAIN OUTCOME MEASURE(S)

The primary endpoints were implantation, pregnancy, and live birth rate (LBR) after single blastocyst transfer. Secondary endpoints included embryo morphokinetics, development of good-quality blastocysts, and euploidy rate.

RESULT(S)

Kinetic data from 10,768 sibling pronucleate embryos cultured in the EmbryoScope were compared. GB embryos initiated compaction earlier and formed morula sooner than their G-TL counterparts. The mean timing for start of blastulation did not differ. The interval between start of blastulation and time of blastocyst formation was observed to be <12 hours for proportionately more GB compared with G-TL-cultured embryos. Despite a higher rate of observed dysmorphisms in GB embryos, the euploidy rate among biopsied blastocysts did not differ between media. A total of 820 single-embryo transfer cycles were performed. Implantation rates were similar between media, independent of whether the embryo transferred was fresh (GB 58.7% vs. G-TL 61.7%) or frozen (GB 64.1% vs. G-TL 60.5%). Live birth rates were also not different. With GB medium, the LBR for fresh and frozen transfers was 54.2% and 53.1%, respectively, as compared with 51.1% and 50%, respectively, with G-TL.

CONCLUSION(S)

Uninterrupted culture in a time-lapse incubator without medium refreshment was well supported by both media tested. Differences in morphokinetics did not necessarily dictate the superiority of one media over the other. Both pregnancy and LBR were not significantly influenced by choice of culture medium. The euploidy rate was also independent of culture medium.

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 INTEREST(S)

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

Comprehensive analysis of whole genome methylation in mouse blastocysts cultured with four different constituents following in vitro fertilization

Background

With the development of assisted reproductive technology (ART), diseases believed to be caused by ART have begun to be identified as imprinted disease. However, no conclusion has been reached. So we sought to determine whether ART procedures disturb gene methylation and whether imprinted genes alone are selectively disturbed. To examine whether the constituents of the culture medium contribute to the changes in methylation, we used a mouse model to conduct IVF and comprehensively analyzed 5′–C–phosphate–G–3′ (CpG) by reduced representation bisulfite sequencing (RRBS) using a second-generation sequencer to determine changes in methylation using four types of culture media with different amino acid constituents.

Results

We cultured ova to the blastocyst stage in a mouse model in culture media with four different amino acid constituents. Each culture medium included (1) KSOM culture medium (NoAA), (2) KSOM media + essential amino acids (EAAs), (3) KSOM medium + non-essential amino acids (NEAAs), or (4) KSOM medium + EAAs + NEAAs (AllAA) analyzed by reduced representation bisulfite sequencing. The results showed that (1) there were many regions that maintained hypermethylation with NEAAs, (2) there was little effect of demethylation on reprogramming in the 5′UTR and promoter regions, and (3) specific changes were observed in imprinted genes such as Nnat and Nespas.

Conclusions

Compared with EAAs, NEAAs could protect genes from demethylation caused by reprogramming. On the imprinted genes, methylation of the promoter region of H19 was decreased by NEAAs, suggesting that specific genes were prone to changes in methylation. It was suggested that these changes could provide similar results in humans. Further studies are needed to understand how changes in methylation may affect gene expression profiles.

Birthweight difference of singletons conceived through in vitro fertilization with frozen versus fresh embryo transfer: An analysis of 5406 embryo transfers in a retrospective study 2013-2018

INTRODUCTION

Perinatal risks after frozen embro transfer (FET) have been reassuring but some authors suggest that birthweights are higher after FET than after fresh embryo transfer (ET). The primary objective of this retrospective study, conducted in Clinique de la Sagesse, Rennes (France) from December 2013 to March 2017, was to determine whether a difference in birthweight exists between children conceived through in vitro fertilization (IVF) with frozen versus fresh ET. The secondary objective was to compare live birth rates after frozen versus fresh cycles.

MATERIAL AND METHODS

All couples undergoing IVF were included. Cycles with gamete donation and twin pregnancies were excluded. Hormone therapy was used in all embryo transfers. The main outcome measures were the child's birthweight, mode of delivery, gestation length and sex, maternal characteristics, and IVF characteristics. The primary endpoint was birthweight.

RESULTS

We studied 5406 embryo transfers and the 708 resulting singleton live births on which birthweight data were available. Mean birthweight was 3357g after frozen embryo transfer versus 3183g after fresh embryo transfer (p<0.001). After adjusting for confounding factors, the children born after frozen embryo transfer were 165.2g heavier (95%CI [92.96-237.51]). No difference was found in gestation length. Live birth was obtained after the 1.6th IVF attempt. Live birth rate was higher for fresh cycles (19% versus 12%, p<0.001), and the caesarean rate lower (16% versus 21%).

DISCUSSION

Birthweight was higher after frozen embryo transfer for a similar gestational age. Further research is needed to elucidate the mechanisms responsible for this difference.

Effect of endometrial thickness on birthweight in frozen embryo transfer cycles: an analysis including 6181 singleton newborns

STUDY QUESTION

Does endometrial thickness (EMT) have an impact on singleton birthweight in frozen embryo transfer (FET) cycles?

SUMMARY ANSWER

An EMT <8 mm was associated with a lower mean birthweight and gestational age- and gender-adjusted birthweight (Z-scores) of singletons resulting from FET.

WHAT IS KNOWN ALREADY

Previous studies have examined the impact of EMT on IVF success rates. Little is known, however, regarding the relationship between EMT and neonatal birthweight.

STUDY DESIGN, SIZE, DURATION

This retrospective study involved singleton live births born to women undergoing frozen-thawed Day 3 embryo transfer during the period from January 2010 to December 2017 at a tertiary care centre.

PARTICIPANTS/MATERIALS, SETTING, METHODS

A total of 6181 women who fulfilled the inclusion criteria were included and were grouped into five groups depending on the EMT: <8 mm, 8-9.9 mm, 10-11.9 mm, 12-13.9 mm and ≥14 mm. EMT between 10 and 11.9 mm was taken as a reference group. Singleton birthweight was the primary outcome measure. A multivariable linear regression analysis was performed to detect a relationship between EMT and newborns' birthweight after controlling for a number of potential confounders.

MAIN RESULTS AND THE ROLE OF CHANCE

A modest but significant decrease in birthweight was observed in the EMT <8 mm group as compared with groups with EMT ≥10 mm, with a mean difference of 89-108 g. Also, singletons from the EMT <8 mm group (0.24 ± 1.04) had a significantly lower birthweight Z-scores than those from the EMT 10-11.9 mm (0.41 ± 1.02; P = 0.032) or EMT 12-13.9 mm (0.46 ± 1.07; P = 0.004) groups. Further, multiple linear regression analyses indicated that parental BMIs, gestational age, newborn gender, pregnancy complications and EMT <8 mm were all independent predictors of neonatal birthweight.

LIMITATIONS, REASONS FOR CAUTION

The present study was limited by its retrospective design. Future prospective studies are required to confirm our findings.

WIDER IMPLICATIONS OF THE FINDINGS

Our findings provided new insight into the relationship between EMT and neonatal outcomes by showing that a thin endometrium is associated with a decrease in singleton birthweight.

STUDY FUNDING/COMPETING INTEREST(S)

National Key Research and Development Program of China (2018YFC1003000); the National Natural Science Foundation of China (81771533, 81571397, 31770989, 81671520); the China Postdoctoral Science Foundation (2018M630456). The authors have no conflicts of interest to declare.

TRIAL REGISTRATION NUMBER

Not applicable.

Overall Blastocyst Quality, Trophectoderm Grade, and Inner Cell Mass Grade Predict Pregnancy Outcome in Euploid Blastocyst Transfer Cycles

Background:

Despite recent advances that have improved the pregnancy success rates that can be achieved via in vitro fertilization (IVF) therapy, it is not yet clear which blastocyst morphological parameters best predict the outcomes of single blastocyst transfer. In addition, most of the previous studies did not exclude the effect of embryo aneuploidy on blastocysts transfer. Thus, the present study investigated the predictive value of various parameters on the pregnancy outcomes achieved via the transfer of frozen euploid blastocysts.

Methods:

The study retrospectively analyzed 914 single euploid blastocyst transfer cycles that were performed at the Peking University Third Hospital Reproductive Medical Center between June 2011 and May 2016. The expansion, trophectoderm (TE), and inner cell mass (ICM) quality of the blastocysts were assessed based on blastocyst parameters, and used to differentiate between “excellent”, “good”, “average”, and “poor”-quality embryos. The relationship between these embryo grades and the achieved pregnancy outcomes was then analyzed via the Chi-square and logistic regression tests.

Results:

For embryo grades of excellent, good, average and poor, the clinical pregnancy rates were 65.0%, 59.3%, 50.3% and 33.3%, respectively; and the live-birth rates were 50.0%, 49.7%, 42.3% and 25.0%, respectively. Both the clinical pregnancy rate (χ² = 21.28, P = 0.001) and live-birth rate (χ² = 13.50, P < 0.001) increased with the overall blastocyst grade. Both rates were significantly higher after the transfer of a blastocyst that exhibited either an A-grade OR B-grade TE, and similarly, an A-grade ICM, than after the transfer of a blastocyst that exhibited a C-grade TE and/or ICM. The degree of blastocyst expansion had no apparent effect on the clinical pregnancy or live-birth rate. All odds ratio were adjusted for patient age, body mass index, length (years) of infertility history, and infertility type.

Conclusions:

A higher overall euploid blastocyst quality is shown to correlate most strongly with optimal pregnancy outcomes. The study thus supports the use of the described TE and ICM morphological grades to augment current embryo selection criteria.

Considerations Regarding Embryo Culture Conditions: From Media to Epigenetics

There are numerous reports on embryo culture media and conditions in the laboratory, as the subject is multifaceted and complex, reflecting the variation in practice. In this scoping review, we attempt to approach the topic of culture media and conditions from the practitioners' perspective aiming to highlight, in a comprehensive fashion, important aspects regarding the options available, introduce points of debate and controversy, while maintaining the viewpoint of the practicing embryologist's concerns.

Increased maternal hCG concentrations in early in vitro pregnancy with elevated basal FSH

Objective

To investigate factors that influence maternal hCG concentration in early pregnancy and the relationship between hCG concentration in early pregnancy and basal FSH (bFSH) level.

Design

Retrospective cohort study.

Setting

Reproductive medical center.

Patient(s)

In total, 482 women aged 22 to 38 years with elevated basal FSH (> 10 IU/L) and who experienced a single live birth after in vitro fertilization-embryo transfer were selected. These 482 women were age-matched with an equal number of women with normal basal FSH (≤10 IU/L) who also experienced a single live birth.

Intervention(s)

None.

Main Outcome Measure(s)

HCG concentration.

Result(s)

The hCG concentrations on Day 14 and Day 21 were 560.46 (363.63–842.52) IU/L and 9862.00 (6512.25–14029.50) IU/L, respectively, in the elevated bFSH group, and these values were significantly increased compared with the normal bFSH group. After adjusting for confounding factors, the concentrations of maternal hCG on Day 14 and Day 21 were significantly associated with basal FSH. In addition, crude linear regression analysis demonstrated that hCG concentrations increased as the basal serum levels of FSH increased.

Conclusion(s)

Elevated basal FSH has implications for the interpretation of hCG concentrations in early pregnancy after in vitro fertilization-embryo transfer (IVF-ET) that led to a single live birth.

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.

The effects of embryo culture media on the birthweight of singletons via fresh or frozen-thawed embryo transfer: a large-scale retrospective study

Background

Embryo culture media used for IVF treatment might affect fetal growth and thus birthweight of the newborns.

Methods

A retrospective study was conducted in South China using data from 2370 singleton neonates born after IVF/ICSI between 2009 and 2012. Two culture media, i.e., either Vitrolife or SAGE were used as embryo culture media during the study period. Neonates’ birthweights were compared between the two embryo culture media groups.

Results

Among the 2370 singletons, 1755 cases came from fresh cleavage embryo transfer while 615 were from frozen-thawed cleavage embryo transfer. Within the fresh embryo transfer newborns, no statistical difference was observed in either birthweight (mean ± SD: 3196.0 ± 468.9 versus 3168.4 ± 462.0g, p > 0.05) or adjusted birthweight controlled for gestational age and gender (z-score mean ± SD: 0.11 ± 1.02 versus 0.11 ± 0.99 g, P > 0.05) between the Vitrolife (n = 419) and the SAGE group (n = 1336). Likewise within frozen embryo transfer neotates, no statistical difference of the birthweight (3300.6 ± 441.3 vs.3256.0 ± 466.7 g, P > 0.05) and adjusted birthweight (0.30 ± 0.99 g versus 0.29 ± 0.97 g, P > 0.05) was found between the Vitrolife (n = 202) and the SAGE group (n = 413). The sex ratio [OR1.17, 95 % CI (0.94–1.46)/OR1.1, 95 % CI (0.78–1.54)], rate of small for gestational age [OR1.14, 95 % CI (0.82–1.59)/OR1.06, 95 % CI (0.56–2.02)] and large for gestational age [OR1.07, 95 % CI (0.64–1.76)/OR0.98, 95 % CI (0.47–2.02)] in fresh and frozen-thawed subgourps are all comparable respectively between the two culture media. No group differences were found in the rate of low birthweight and macosomia. Multiple linear regression analysis demonstrated that maternal weight, gestational age, frozen-thawed embryo transfer and infant gender were significantly related to neonatal birthweight (P < 0.001).

Conclusions

It appears that embryos cultured in SAGE or Vitrolife media after fresh or frozen-thawed cleavage embryo transfer did not affect neonate’s birthweight.

Phenotypic developmental plasticity induced by preincubation egg storage in chicken embryos (Gallus gallus domesticus)

The developing chicken blastoderm can be temporarily maintained in dormancy below physiological zero temperature. However, prolonged preincubation egg storage impairs normal morphological and physiological development of embryos in a potential example of fetal programming (in this case, “embryonic programming”). We investigated how preincubation egg storage conditions (temperature, duration, hypoxia, and hypercapnia) affects viability, body mass, and physiological variables and functions in day 15 chicken embryos. Embryo viability was impaired in eggs stored for 2 and 3 weeks, with the effects greater at 22°C compared to 15°C. However, embryo size was reduced in eggs stored at 15°C compared with 22°C. Phenotypic change resulting from embryonic programming was evident in the fact that preincubation storage at 15°C diminished hematocrit (Hct), red blood cell concentration ([RBC]), and hemoglobin concentration ([Hb]). Storage duration at 15°C more severely affected the time course (2, 6, and 24 h) responses of Hct, [RBC], and [Hb] to progressive hypoxia and hypercapnia induced by submersion compared with storage duration at 22°C. The time‐specific regulation of acid–base balance was changed progressively with storage duration at both 22 and 15°C preincubation storages. Consequently, preincubation egg storage at 22°C resulted in poor viability compared with eggs stored at 15°C, but size and physiological functions of embryos in eggs stored for 1–2 weeks were worse in eggs stored in the cooler than stored under room conditions. Avian eggs thus prove to be useful for examining developmental consequences to physiology of altered preincubation thermal environment in very early stages of development (embryonic programming).

Influence of embryo culture medium (G5 and HTF) on pregnancy and perinatal outcome after IVF: a multicenter RCT

STUDY QUESTION

Does embryo culture medium influence pregnancy and perinatal outcome in IVF?

SUMMARY ANSWER

Embryo culture media used in IVF affect treatment efficacy and the birthweight of newborns.

WHAT IS KNOWN ALREADY

A wide variety of culture media for human preimplantation embryos in IVF/ICSI treatments currently exists. It is unknown which medium is best in terms of clinical outcomes. Furthermore, it has been suggested that the culture medium used for the in vitro culture of embryos affects birthweight, but this has never been demonstrated by large randomized trials.

STUDY DESIGN, SIZE, DURATION

We conducted a multicenter, double-blind RCT comparing the use of HTF and G5 embryo culture media in IVF. Between July 2010 and May 2012, 836 couples (419 in the HTF group and 417 in the G5 group) were included. The allocated medium (1:1 allocation) was used in all treatment cycles a couple received within 1 year after randomization, including possible transfers with frozen-thawed embryos. The primary outcome was live birth rate.

PARTICIPANTS/MATERIALS, SETTING, METHODS

Couples that were scheduled for an IVF or an ICSI treatment at one of the six participating centers in the Netherlands or their affiliated clinics.

MAIN RESULTS AND THE ROLE OF CHANCE

The live birth rate was higher, albeit nonsignificantly, in couples assigned to G5 than in couples assigned to HTF (44.1% (184/417) versus 37.9% (159/419); RR: 1.2; 95% confidence interval (CI): 0.99-1.37; P = 0.08). Number of utilizable embryos per cycle (2.8 ± 2.3 versus 2.3 ± 1.8; P < 0.001), implantation rate after fresh embryo transfer (20.2 versus 15.3%; P < 0.001) and clinical pregnancy rate (47.7 versus 40.1%; RR: 1.2; 95% CI: 1.02-1.39; P = 0.03) were significantly higher for couples assigned to G5 compared with those assigned to HTF. Of the 383 live born children in this trial, birthweight data from 380 children (300 singletons (G5: 163, HTF: 137) and 80 twin children (G5: 38, HTF: 42)) were retrieved. Birthweight was significantly lower in the G5 group compared with the HTF group, with a mean difference of 158 g (95% CI: 42-275 g; P = 0.008). More singletons were born preterm in the G5 group (8.6% (14/163) versus 2.2% (3/137), but singleton birthweight adjusted for gestational age and gender (z-score) was also lower in the G5 than in the HTF group (-0.13 ± 0.08 versus 0.17 ± 0.08; P = 0.008).

LIMITATIONS, REASONS FOR CAUTION

This study was powered to detect a 10% difference in live births while a smaller difference could still be clinically relevant. The effect of other culture media on perinatal outcome remains to be determined.

WIDER IMPLICATIONS OF THE FINDINGS

Embryo culture media used in IVF affect not only treatment efficacy but also perinatal outcome. This suggests that the millions of human embryos that are cultured in vitro each year are sensitive to their environment. These findings should lead to increased awareness, mechanistic studies and legislative adaptations to protect IVF offspring during the first few days of their existence.

STUDY FUNDING/COMPETING INTERESTS

This project was partly funded by The NutsOhra foundation (Grant 1203-061) and March of Dimes (Grant 6-FY13-153). The authors declare no conflict of interest.

TRIAL REGISTRATION NUMBER

NTR1979 (Netherlands Trial Registry).

TRIAL REGISTRATION DATE

1 September 2009.

DATE OF FIRST PATIENT'S ENROLMENT

18 July 2010.

The 'Developmental Origins' Hypothesis: relevance to the obstetrician and gynecologist

The recognition of 'fetal origins of adult disease' has placed new responsibilities on the obstetrician, as antenatal care is no longer simply about ensuring good perinatal outcomes, but also needs to plan for optimal long-term health for mother and baby. Recently, it has become clear that the intrauterine environment has a broad and long-lasting impact, influencing fetal and childhood growth and development as well as future cardiovascular health, non-communicable disease risk and fertility. This article looks specifically at the importance of the developmental origins of ovarian reserve and ageing, the role of the placenta and maternal nutrition before and during pregnancy. It also reviews recent insights in developmental medicine of relevance to the obstetrician, and outlines emerging evidence supporting a proactive clinical approach to optimizing periconceptional as well as antenatal care aimed to protect newborns against long-term disease susceptibility.

Do We Pay Enough Attention to Culture Conditions in Context of Perinatal Outcome after In Vitro Fertilization? Up-to-Date Literature Review

Adverse perinatal outcomes in singleton IVF pregnancies have been most often explained by parental underlying diseases and so far laboratory conditions during embryo culture are still not explored well. The following review discusses the current state of knowledge on the influence of IVF laboratory procedures on the possible perinatal outcome. The role of improved media for human embryo culture is unquestionable. Addition of certain components to culture media and their effect on embryo survival and implantation rates have been taken into consideration recently and studied on animal model. Impact of media on perinatal outcome in IVF offspring has also been studied. It has been discovered that epigenetic changes and neonatal birth weight are probably associated with the use of specific culture media, as is the relation between placental size and its influence on perinatal outcome. There are still questions in the discussion about duration of embryo culture (cleavage stage versus blastocyst transfer). Some of the IVF methods, such as in vitro maturation of oocytes and freezing/thawing procedures, also require well-powered randomized controlled trials in order to define their exact impact on perinatal outcome. Constant further research is needed to assess the impact of laboratory environment on fetal and postnatal development.

Amino acid composition of human uterine fluid: association with age, lifestyle and gynaecological pathology

STUDY QUESTION

Do the amino acid levels of human uterine fluid vary with age, BMI, phase of menstrual cycle, benign pathology or diet?

SUMMARY ANSWER

The levels of 18 amino acids in human uterine fluid were shown to be affected only by maternal diet.

WHAT IS KNOWN ALREADY

Murine, bovine and ovine uterine amino acid content has been reported, but no reliable data on the human exist. Murine studies have demonstrated that the intrauterine periconceptional nutritional environment is affected by maternal diet.

STUDY DESIGN, SIZE, DURATION

Uterine secretions were aspirated from 56 women aged 18–45 years. The women were recruited preoperatively from gynaecological theatre operating schedules or hysterosalpingo-contrast-sonography (HyCoSy) lists. A proportion of these women had proven fertility; however, the majority were being investigated for subfertility. The BMI, gynaecological history and dietary pattern of these women were also assessed.

PARTICIPANTS/MATERIALS, SETTING, METHODS

Reverse phase high performance liquid chromatography was used to analyse the concentrations of 18 amino acids within the uterine fluid and blood serum. The results were analysed against the women's stage of cycle, age, BMI and diet.

MAIN RESULTS AND THE ROLE OF CHANCE

The profile of 18 amino acids in uterine fluid was described. In total, human uterine fluid was observed to contain an amino acid concentration of 3.54 mM (interquartile range: 2.27–6.24 mM). The relative concentrations of 18 amino acids were not significantly altered by age, BMI, cycle phase or the presence of specific benign gynaecological pathologies. However, a diet identified by a validated scoring system as being less healthy was associated with higher concentrations of asparagine (P = 0.018), histidine (P = 0.011), serine (P = 0.033), glutamine (P = 0.049), valine (P = 0.025), phenylalanine (P = 0.019), isoleucine (P = 0.025) and leucine (P = 0.043) in the uterine fluid compared with a healthier diet, defined as one with a higher intake of fresh vegetables, fruit, whole-grain products and fish and a low intake of red and processed meat and high fat dairy products. There were no significant correlations between serum amino acid concentrations and those in the uterine fluid.

LIMITATIONS, REASONS FOR CAUTION

Our results enabled us to detect the effect of diet on the concentrations of amino acids in human uterine fluid; however, the study may not have had sufficient numbers to detect mild effects of BMI or age.

WIDER IMPLICATIONS OF THE FINDINGS

These findings increase our understanding of the nutritional environment encountered by the preimplantation embryo, and indicate how periconceptional diet may alter this. Given the importance of early embryo environment for programming of development and future health, this information may aid in the development of nutritional interventions aimed at optimizing the preimplantation phase of human embryo development in vivo.

STUDY FUNDING/COMPETING INTEREST(S)

This work was funded by the NIHR, the Medical Research Council (G0701153) and the University of Southampton and was supported by the NIHR BRC in Nutrition and Southampton University NHS Foundation Trust. The authors declare no conflicts of interest.

Does the type of culture medium used influence birthweight of children born after IVF?

STUDY QUESTION

Do culture media influence birthweight of children born after IVF?

SUMMARY ANSWER

Some studies have observed a significant effect of culture media on birthweight, while others have not, but since most studies compared different culture media, conventional meta-analysis was not possible.

WHAT IS KNOWN ALREADY

Animal studies suggest that in vitro culture of embryos can have a significant effect on the birthweight of offspring when compared with in vivo developed embryos. The type of culture medium (or certain components of the medium) used is one of the causal factors.

STUDY DESIGN, SIZE, DURATION

We reviewed all available literature reporting on a relation between culture medium and birthweight in human studies and a selection of animal studies.

PARTICIPANTS/MATERIALS, SETTING, METHODS

An extensive literature search on Pubmed and Medline was performed with relevant search criteria relating to IVF, birthweight and culture medium.

MAIN RESULTS AND THE ROLE OF CHANCE

Eleven studies reporting on a relationship between culture medium and birthweight in human were included in this review. Five of these found significant differences in birthweight when offspring born after culture in different culture media were compared. The remaining studies did not find differences in birthweight after changing culture medium.

LIMITATIONS, REASONS FOR CAUTION

The number of human studies is limited and different culture media with different compositions are compared which makes a comparison between the studies difficult, if not impossible. Furthermore, most study designs were retrospective with consecutive use of different culture media and limited sample sizes, which makes bias of the results likely.

WIDER IMPLICATIONS OF THE FINDINGS

If it could be confirmed that the type of culture medium used does indeed influence phenotypic characteristics (such as birthweight) of children born after IVF, it would underline the importance of monitoring the health of IVF children in relation to aspects of the laboratory techniques used during embryo culture.

STUDY FUNDING/COMPETING INTERESTS

No funding was applicable to this study. No conflict of interest is declared.

The type of culture medium and the duration of in vitro culture do not influence birthweight of ART singletons

STUDY QUESTION

Does the type of in vitro culture medium or the duration of in vitro culture influence singleton birthweight after IVF/ICSI treatment?

SUMMARY ANSWER

In a comparison of two culture media, neither the medium nor the duration of culture (Day 3 versus Day 5 blastocyst transfer) had any effect on mean singleton birthweight.

WHAT IS KNOWN ALREADY

Previous studies indicated that in vitro culture of human embryos may affect birthweight of live born singletons. Both the type of culture medium and the duration of culture may be implicated. However, these studies are small and report conflicting results.

STUDY DESIGN, SIZE, DURATION

A large retrospective analysis was performed including all singleton live births after transferring fresh Day 3 or Day 5 embryos. IVF and ICSI cycles performed between April 2004 and December 2009 at a tertiary care centre were included for analysis.

PARTICIPANTS/MATERIALS, SETTING, METHODS

A total of 2098 singleton live births resulting from singleton pregnancies were included for analysis. Two different sequential embryo culture media were concurrently used in an alternating way: Medicult (n = 1388) and Vitrolife (n = 710). Maternal age, maternal and paternal BMI, maternal parity, maternal smoking, main cause of infertility, cycle rank, stimulation protocol, method of fertilization (IVF or ICSI), time in culture and number of embryos transferred were taken into account. Embryo transfers were performed either on Day 3 (n = 1234) or on Day 5 (n = 864). Singleton birthweight was the primary outcome parameter. Gestational age and gender of the newborn were accounted for in the multiple regression analysis.

MAIN RESULTS AND THE ROLE OF CHANCE

No significant differences in mean singleton birthweight were observed between the two culture media: Medicult 3222 g (±15 SE) and Vitrolife 3251 g (±21 SE) (P = 0.264). The mean singleton birthweight was not different between Day 3 embryo transfers (3219 ± 16 g) and Day 5 blastocyst transfers (3250 ± 19 g; P = 0.209). Multiple regression analysis controlling for potential maternal, paternal, treatment and newborn confounders confirmed the non-significant differences in mean singleton birthweight between the two culture media. Likewise, the adjusted mean singleton birthweight was not different according to the duration of in vitro culture (P = 0.521).

LIMITATIONS, REASONS FOR CAUTION

The conclusions are limited by its retrospective design; however, the two different sequential culture systems were used in an alternating way during the same time period. Pregnancy-associated factors possibly influencing birthweight (such as diabetes, hypertension, pre-eclampsia) were not included in the analysis.

WIDER IMPLICATIONS OF THE FINDINGS

This large retrospective study does not support earlier concerns that both the type of culture medium and the duration of embryo culture influence singleton birthweight. However, a continuous surveillance of human embryo culture procedures (medium type, culture duration and other culture conditions) should remain a priority within assisted reproduction technology.

STUDY FUNDING/COMPETING INTERESTS

None.

The clinical outcomes of day 3 4-cell embryos after extended in vitro culture

OBJECTIVE

To evaluate the development potential and clinical significance of day 3 4-cell embryos after extended in vitro culture.

METHODS

This study was a retrospective cohort study for patients with infertility treatment between January 2011 and July 2013. Patients undergoing blastocyst culture in controlled ovarian hyperstimulation cycles using surplus embryos were analyzed in the study. A total of 764 women undergoing blastocyst culture with 1,522 surplus 4-cell embryos on day 3 were analyzed. An additional 2,391 patients with embryos undergoing blastocyst culture during the same period with embryos having more blastomeres were chosen as control.

RESULTS

After extended culture, 253 embryos from 183 cycles in the study group which developed to blastocysts were frozen, and 118 embryos were warmed in subsequent frozen embryo transfer cycles. Implantation rates, clinical pregnancy rates (PRs) and ongoing PRs were 33.3 %, 38.4 % and 31.4 %, respectively, which were similar to those of the control group. The singleton birth weights of newborns using these blastocysts showed no significant difference to that seen in the control group.

CONCLUSION

Surplus 4-cell embryos on day 3 displayed lower blastulation rates. However, once a blastocyst is obtained, it has equivalent clinical outcomes. Embryos that are developmentally lagging on day 3 can be observed in extended culture to increase the cumulative chances of a successful pregnancy.

Evaluation of syphilis serostatus on the safety of IVF treatment

An increasing number of infertile syphilis-infected individuals have turned to assisted reproductive technology; however, the safety of syphilis carrier serostatus on IVF and embryo transfer outcomes has not been evaluated. Data from 482 patients who delivered singletons were analysed. In the retrospective study, the rate of IVF and intracytoplasmic sperm injection fertilization was 79.50% ± 17.57%/78.72% ± 16.66% in the Treponema pallidum particle agglutination assay negative (TPPA-negative) and rapid plasma reagin negative (RPR-negative) group, 76.12% ± 22.99%/74.05% ± 20.31% in the TPPA-positive and RPR-negative group, and 75.66% ± 21.72%/70.90% ± 16.11% in the TPPA-positive and RPR-positive group. The clinical pregnancy rate was 39.79% in the TPPA-negative and RPR-negative group, 46.30% in the TPPA-positive and RPR-negative group, and 36.59% in the TPPA-positive and RPR-positive group. No significant differences were found between the groups. The neonatal gestational age and mean birth weight were not significantly different between the TPPA-negative and TPPA-positive groups. Multiple linear regression analysis also showed no association between TPPA serostatus and newborn birth weight and gestational age. The present retrospective study showed that TPPA and RPR serostatus did not affect the outcomes of IVF and embryo transfer. Syphilis-infected individuals can undergo IVF and embryo transfer cycles after penicillin treatment.

ACE consensus meeting report: culture systems

The UK Association of Clinical Embryologists held a workshop on Culture Systems for assisted conception in Sheffield on 22 May 2013. The meeting was organised in the light of the availability of numerous commercial products for the culture of human preimplantation embryos in vitro and the absence of data comparing the performance of these products. Expert opinions were presented, along with survey data provided by participating IVF Centres. The workshop highlighted the lack of a sound evidence base to support the selection of any one commercial product over another, and raised concerns over the lack of information defining precisely the composition of media, and the potential for adverse long-term effects of such products following their use in assisted conception.

Birth and perinatal outcomes and complications for babies conceived following ART

Children born after assisted reproductive techniques (ART) have an increased risk of several adverse perinatal outcomes compared with their naturally conceived peers. This has various causes such as higher multiple birth rates, parental characteristics and higher maternal age, with more being nulliparous. Furthermore the in-vitro techniques, the controlled ovarian stimulation, culture media, and possibly additional freezing or vitrification procedures seem to play a role. However, when analyzing the perinatal trends over time, the differences between ART and naturally conceived children appear to have diminished. This is probably due to ART being more accessible and therefore couples have shorter duration of infertility before referral to ART; hence couples are nowadays less reproductively ill than in the past. A refinement of both clinical and laboratory skills during the past three decades of assisted reproduction may be another explanation. However, caution should be taken, as we do not yet know the full consequences of the observed increase in fetal growth and potential epigenetic changes in the early embryonic stages of fetal development.

The impact of assisted reproductive technologies on intra-uterine growth and birth defects in singletons

Pooled odds ratios from meta-analyses of infants born following assisted reproductive technologies (ART) compared with non-ART singletons show increases in low birth weight, preterm birth, small for gestational age, and birth defects. Although there have been small reductions in recent data, odds associated with these outcomes are still higher for ART singletons. Both ART procedures and underlying infertility contribute to these increased risks. Outcomes appear better for frozen-thawed compared with fresh embryo transfers, but are poorer than for non-ART infants. There is a concerning increase in large-for-gestational-age infants born following frozen-thawed embryo transfer and limited data on the effects of embryo vitrification used instead of slow-freezing techniques. Using large datasets, we now need to investigate risks of individual birth defects and disentangle the inter-related effects of different types of infertility and the multiple aspects of ART. Greater understanding of the causes of adverse ART outcomes and identification of modifiable risk factors may lead to further reductions in the disparities in outcome between ART and non-ART infants.

Birthweight distribution in ART singletons resulting from embryo culture in two different culture media compared with the national population

STUDY QUESTION

Is there a difference in birthweight distribution in ART singletons born after IVF culture in two different culture media?

SUMMARY ANSWER

There is no effect of culture media on both crude and adjusted birthweight distributions in ART singletons from nulliparous mothers.

WHAT IS KNOWN ALREADY

Studies on human ART singletons have reported a difference in birthweight in singletons following IVF culture in different culture media. However, other studies comparing different culture media have not shown any significant differences in birthweight.

STUDY DESIGN, SIZE, DURATION

This study was a retrospective comparison of birthweights in IVF/ICSI singletons conceived after fresh embryo transfer following embryo culture in Cook or Medicult medium and in a national cohort of naturally conceived singletons in nulliparous women. The study compares four independent groups consisting of singletons in nulliparous women from Cook-d2: 2-day culture in Cook medium at Rigshospitalet (n = 974), Medicult-d2: 2-day culture in Medicult EmbryoAssist medium at Rigshospitalet (n = 147), Medicult-d3: 3-day culture in Medicult EmbryoAssist medium with and without added GM-CSF (n = 204), and DK: pregnancies from the Danish birth registry (n = 106842).

PARTICIPANTS/MATERIALS, SETTING, METHODS

The study compares the birthweights of singletons from nulliparous women in the four independent groups mentioned above; Cook-d2: Medicult-d2: Medicult-d3: and DK. In addition, distributions of large and small for gestational age infants were compared between the groups and a multiple linear regression analysis was used to determine which factors determined birthweight.

MAIN RESULTS AND THE ROLE OF CHANCE

We found no significant difference in the crude birthweight distributions between singletons born after culture in Cook-d2 or Medicult-groups. Singleton girls from the Cook-d2 group weighed 3302 ± 28 g, versus 3252 ± 76 in the Medicult-d2 group (difference 50 g; P = 0.547). Singleton boys from the Cook-d2 group weighed 3430 ± 27 g, versus 3354 ± 56 in the Medicult-d2 group (difference 76 g; P = 0.279). In the background population, mean birthweights for singleton girls and boys were 3383 ± 2.4 g and 3494 ± 2.5 g, respectively. The mean birthweights of girls, 3315 ± 61 g, and boys, 3383 ± 64 g, in the Medicult-d3 group were not significantly different from that in the Medicult-d2 group. When pooling data from all culture media groups, we found the same slightly lower mean birthweight in IVF/ICSI singletons when compared with the national birth cohort as has been previously reported (Cook-d2 + Medicult-d2 + d3 versus birth cohort; girls: P < 0.001, boys: P < 0.001). We also pooled data on boys and girls and calculated the mean birthweight for the Cook-d2, Medicult-d2 and Medicult-d3 groups and found no significant differences.

LIMITATIONS, REASONS FOR CAUTION

The retrospective design and the inherent risk of confounding factors is a limitation. Selection bias cannot be excluded as the embryos cultured in Cook-d2 and Medicult-d2 were from single centre studies while data in Medicult-D3 group were derived from a multicentre study.

WIDER IMPLICATIONS OF THE FINDINGS

This large cohort of singletons born after IVF/ICSI shows no difference in crude mean birthweight after culture in two different culture media, indicating that if such a difference exists, this must be specific for certain culture media. As expected we found a slightly lower mean birthweight in ART compared with naturally conceived singletons. This suggests that parental characteristics or IVF technique related factors other than type of culture medium may influence the birthweight in ART singletons.

STUDY FUNDING/COMPETING INTERESTS

No external funding was used for this study. No conflicts of interest are declared.

IVF culture media: past, present and future

BACKGROUND

The advances in the world of IVF during the last decades have been rapid and impressive and culture media play a major role in this success. Until the 1980s fertility centers made their media in house. Nowadays, there are numerous commercially available culture media that contain various components including nutrients, vitamins and growth factors. This review goes through the past, present and future of IVF culture media and explores their composition and quality assessment.

METHODS

A computerized search was performed in PubMed regarding IVF culture media including results from 1929 until March 2014. Information was gathered from the websites of companies who market culture media, advertising material, instructions for use and certificates of analysis. The regulation regarding IVF media mainly in the European Union (EU) but also in non-European countries was explored.

RESULTS

The keyword 'IVF culture media' gave 923 results in PubMed and 'embryo culture media' 12 068 results dating from 1912 until March 2014, depicting the increased scientific activity in this field. The commercialization of IVF culture media has increased the standards bringing a great variety of options into clinical practice. However, it has led to reduced transparency and comparisons of brand names that do not facilitate the scientific dialogue. Furthermore, there is some evidence suggesting that suboptimal culture conditions could cause long-term reprogramming in the embryo as the periconception period is particularly susceptible to epigenetic alterations. IVF media are now classified as class III medical devices and only CE (Conformité Européene)-marked media should be used in the EU.

CONCLUSION

The CE marking of IVF culture media is a significant development in the field. However, the quality and efficiency of culture media should be monitored closely. Well-designed randomized controlled trials, large epidemiological studies and full transparency should be the next steps. Reliable, standardized models assessing multiple end-points and post-implantation development should replace the mouse embryo assay. Structured long-term follow-up of children conceived by assisted reproduction technologies and traceability are of paramount importance.

Composition of commercial media used for human embryo culture

OBJECTIVE

To determine the composition of commercially available culture media and test whether differences in composition are biologically relevant in a murine model.

DESIGN

Experimental laboratory study.

SETTING

University-based laboratory.

ANIMAL(S)

Cryopreserved hybrid mouse one-cell embryos were used in experiments.

INTERVENTION(S)

Amino acid, organic acid, ions, and metal content were determined for two different lots of media from Cook, In Vitro Care, Origio, Sage, Vitrolife, Irvine CSC, and Global. To determine whether differences in the composition of these media are biologically relevant, mouse one-cell embryos were thawed and cultured for 120 hours in each culture media at 5% and 20% oxygen in the presence or absence of protein in an EmbryoScope time-lapse incubator.

MAIN OUTCOME MEASURE(S)

The compositions of seven culture media were analyzed for concentrations of 39 individual amino acids, organic acids, ions, and elements. Blastocyst rates and cell cycle timings were calculated at 96 hours of culture, and the experiments were repeated in triplicate.

RESULT(S)

Of the 39 analytes, concentrations of glucose, lactate, pyruvate, amino acids, phosphate, calcium, and magnesium were present in variable concentrations, likely reflecting differences in the interpretation of animal studies. Essential trace elements, such as copper and zinc, were not detected. Mouse embryos failed to develop in one culture medium and were differentially affected by oxygen in two other media.

CONCLUSION(S)

Culture media composition varies widely, with differences in pyruvate, lactate, and amino acids especially notable. Blastocyst development was culture media dependent and showed an interaction with oxygen concentration and presence of protein.

Birth defects and congenital health risks in children conceived through assisted reproduction technology (ART): a meeting report

PURPOSE

Assisted Reproduction Treatment (ART) is here to stay. This review addresses the parental background of birth defects, before, during and after conception and focuses both on the underlying subfertility and on the question whether ART as a treatment is an additional contributing factor.

METHODS

Searches were performed in Medline and other databases. Summaries were discussed in a Delphi panel set-up by the European Society of Human Reproduction and Embryology (ESHRE).

RESULTS

Several birth defects and adult diseases arise during the earliest stages of ovarian development and oocyte differentiation: this is the case of cleft palate disorders in offspring from female rat exposed to Dioxin during fetal life or the polycystic ovary diseases in female offspring (primates) exposed to elevated androgen concentration during fetal life. Human oocytes and embryos often fail to stop the propagation of aneuploid cells but maintain their ability to repair DNA damages including those introduced by the fertilizing sperm. There is a 29 % increased risk of birth defects in the newborns spontaneously conceived by subfertile couples and the risk is further increased (34 %) when conception is achieved by treating infertlity with ART (Danish IVF Registry). Periconceptional conditions are critical for ART babies: their birth weight is in general smaller (Norvegian Registry) but a more prolonged culture time doubled the number of large babies (Finnish Registry).

CONCLUSION

The long-term developmental effects of ART on child and subsequent health as an adult remains a subject worthy of futher monitoring and investigation.

The protein source in embryo culture media influences birthweight: a comparative study between G1 v5 and G1-PLUS v5

STUDY QUESTION

Does protein source or human serum albumin (HSA) in embryo culture media influence the subsequent birthweight?

SUMMARY ANSWER

A significant difference was observed in gestational age- and gender-adjusted birthweight (Z scores) and the proportion of large-for-gestational age (LGA) babies between embryos cultured in G1 v5 and those cultured in G1-PLUS v5 media.

WHAT IS KNOWN ALREADY

It has been reported that the birthweights of singletons born from embryos cultured in Vitrolife are significantly higher than those cultured in the Cook group of media, and that G1-PLUS (Vitrolife, Gothenburg, Sweden) is associated with increased birth and placenta weights compared with Medicult ISMI.

STUDY DESIGN, SIZE, AND DURATION

This study was a retrospective analysis of neonatal birthweights, and included 1097 singletons born from fresh embryo transfer cycles at the Center for Reproductive Medicine of Peking University Third Hospital between January 2011 and August 2012. The number of singletons born from G1 v5 culture media was 489, and the number of singletons born from G1-PLUS v5 media was 608.

PARTICIPANTS/MATERIALS, SETTING, AND METHODS

Patients <40 years of age with a BMI <30 kg/m² were analysed. Only data from newborns from singleton pregnancies and born alive after the 28th week of gestation were included. Patients with a vanishing twin or with pregnancy-related complications, such as diabetes and hypertension, were excluded, as were patients who received preimplantation genetic diagnosis or used donor oocytes. Multiple linear regression analysis was performed to determine the influence of individual factors on birthweights of singleton newborns. The birthweights and Z scores of singletons and LGA babies were compared between the G1 v5 and G1-PLUS v5 media groups.

MAIN RESULTS AND THE ROLE OF CHANCE

The absolute birthweights for singletons resulting from G1-PLUS v5 were not different from singletons resulting from G1 v5 (3375.9 ± 479.6 g versus 3333.2 ± 491.6 g, respectively; P = 0.14). However the Z scores for singletons from embryos cultured in G1-PLUS v5 were significantly higher than for singletons cultured in G1 v5 (0.28 ± 1.12 versus 0.09 ± 1.15, respectively; P = 0.04), and more LGA babies were born from G1-PLUS v5 culture compared with G1 v5 (16.8 versus 12.1%, respectively; P = 0.03) culture. Finally, multiple linear regression analysis suggested that female weight (P = 0.00), male height (P = 0.04), gestational age at birth (P = 0.00), infant gender (P = 0.00) and culture media (P = 0.04) all had significant effects on the birthweights of singleton newborns.

LIMITATIONS AND REASONS FOR CAUTION

This study was limited by its retrospective design.

WIDER IMPLICATIONS OF THESE FINDINGS

Our study suggests that protein source/HSA has a significant effect on birthweights of singleton newborns.

STUDY FUNDING/COMPETING INTEREST(S)

This study was funded by the National Natural Science Foundation of China for Young Scholars (81300483). The authors have no conflicts of interest to declare.

TRIAL REGISTRATION NUMBER

Not applicable.

The safety of long-term cryopreservation on slow-frozen early cleavage human embryos

OBJECTIVE

To evaluate the impact of cryopreservation storage time on cleavage-stage embryo survival rate, pregnancy rate, implantation rate, singleton birth weight, and live birth rate.

METHODS

This study was a retrospective analysis, including 867 thaw cycles and 3,367 embryos. Women who underwent IVF-FET cycles between 2005 and 2012 were analyzed. The patients were divided into four groups, as follows: group 1 (12-23 months); group 2 (24-35 months); group 3 (36-48 months); and group 4 (≥48 months).

RESULTS

The storage time did not have a significant effect on survival, damage rate of the blastomeres, implantation rate, pregnancy rate, singleton birth weight, and live birth rate for embryos frozen at cleavage stages.

CONCLUSION

Storage time did not influence the survival and pregnancy outcomes of slow-frozen early cleavage human embryos. The developmental potential of cryopreserved human embryos with different storage times does not appear to have a negative influence on further development.

Effect of in vitro culture period on birthweight of singleton newborns

STUDY QUESTION

Does prolonged in vitro culture influence newborn birthweight?

SUMMARY ANSWER

The absolute mean birthweight and gestational age- and gender-adjusted birthweight (Z scores) of singletons born from blastocyst transfer are higher than singletons born from Day 3 transfer.

WHAT IS KNOWN ALREADY

An increased proportion of large-for-gestational age (LGA) newborns occurs after blastocyst transfer compared with Day 2 transfer, and Z scores for newborns after blastocyst transfer are higher than newborns after transfer on Day 2 or Day 3.

STUDY DESIGN, SIZE AND DURATION

This study was a retrospective analysis of newborn birthweight, including 2929 singletons at the Reproductive Medical Center of Peking University Third Hospital between January 2009 and June 2012. The number of singletons after Day 3 transfer was 2833 and the number of singletons after blastocyst transfer (Day 5-6) was 96.

PARTICIPANTS/MATERIALS, SETTING, AND METHODS

Only cycles with fresh embryo transfer were included. Patients ≤40 years of age with a BMI < 30 kg/m(2) were analyzed. Only data from singleton newborns born alive after the 20th week of gestation were included in the data analysis. Patients with more than one fetal sac diagnosed by ultrasound but who delivered singletons were excluded. Patients who received PGD and cycles with donor oocytes were excluded. Multiple linear regression analysis was performed to determine the significance of individual factors on absolute birthweight of singleton newborns. The absolute birthweight and Z scores of singletons were compared.

MAIN RESULTS AND THE ROLE OF CHANCE

Multiple linear regression analysis indicated that maternal age, maternal BMI, paternal BMI, type of infertility, gestational age, infant gender and culture period were significantly associated with birthweight. The absolute birthweight for singletons resulting from blastocyst transfer was significantly greater than singletons resulting from Day 3 transfer (3465.31 ± 51.36 versus 3319.82 ± 10.04 g respectively, P = 0.009). The Z scores for singletons after blastocyst transfer were significantly higher than singletons after Day 3 transfer (0.347 versus 0.029 respectively, P = 0.016).

LIMITATIONS AND REASONS FOR CAUTION

In our clinic, blastocyst culture is mainly offered to patients with unsuccessful IVF cycles but also to patients with uterine malformations, and therefore this protocol introduced a potential selection bias in our study. Moreover, as certain culture media are associated with fetal overgrowth, the media used may be also a confounding factor, even though the absolute birthweights of singletons were comparable.

WIDER IMPLICATIONS OF THESE FINDINGS

Our study suggests that a prolonged (5-6 days) in vitro culture period has a significant effect on the mean absolute birthweight and Z scores of singleton newborns. The effect of prolonged in vitro culture on epigenetic changes in the embryo needs further study.

STUDY FUNDING/COMPETING INTEREST(S)

National Natural Science Foundation of China for Young Scholars (81300483). The authors have no conflicts of interest to declare.

TRIAL REGISTRATION NUMBER

Not applicable.

Effects of embryo culture media do not persist after implantation: a histological study in mice

STUDY QUESTION

Is post-implantation embryonic development after blastocyst transfer affected by exposure to different assisted reproduction technology (ART) culture media?

SUMMARY ANSWER

Fetal development and placental histology of ART embryos cultured in vitro in different ART media was not impaired compared with embryos grown in vivo.

WHAT IS KNOWN ALREADY

The application of different in vitro culture (IVC) media for human ART has an effect on birthweight of newborns. In the mouse model, differences in blastocyst formation were reported after culture in different ART media. Moreover, abnormalities in the liver and heart have been detected as a result of suboptimal IVC conditions.

STUDY DESIGN, SIZE, DURATION

Fertilized oocytes from inbred and outbred breeding schemes were retrieved and either immediately transferred to foster mothers or incubated in control or human ART culture media up to the blastocyst stage prior to transfer. Placental and fetal anatomy and particularly bone development were evaluated.

PARTICIPANTS/MATERIALS, SETTING, METHODS

B6C3F1 female mice were used as oocyte donors after ovulation induction. C57Bl/6 and CD1 males were used for mating and CD1 females as foster mothers for embryo transfer. Fertilized oocytes were recovered from mated females and incubated in sequential human ART media (ISM1/ISM2 and HTF/Multiblast), in control media [KSOM(aa) and Whitten's medium] or grown in utero without IVC (zygote control). As in vivo, control B6C3F1 females were superovulated and left untreated. Fetuses and placentae were isolated by Caesarean section and analysed at 18.5 days post-coitum (dpc) for placenta composition and at 15.5 dpc for body weight, crown-rump length (CRL), fetal organ development, morphological development, total bone length and extent of bone ossification.

MAIN RESULTS AND THE ROLE OF CHANCE

No major differences in the number of implantation sites or in histological appearance of the placentae were detected. CRL of KSOM(aa) fetuses was higher compared with zygote control and Whitten's medium. Histological analysis of tissue sections revealed no gross morphological differences compared with the in vitro groups or in vivo controls. Furthermore, no changes in skeletal development and degree of ossification were observed. However, fibula and tibia of ISM1/ISM2 fetuses were longer than the respective ones from in vivo fetuses.

LIMITATIONS, REASONS FOR CAUTION

Findings in the mouse embryo and fetus may not be fully transferable to humans. In addition to skeletal development and placentation, there may be other parameters, e.g. on the molecular level which respond to IVC in ART media. Some comparisons have limited statistical power.

WIDER IMPLICATIONS OF THE FINDINGS

Our data suggest that once implantation is achieved, subsequent post-implantation development unfolds normally, resulting in healthy fetuses. With mouse models, we gather information for the safety of human ART culture media. Our mouse study is reassuring for the safety of ART conditions on human embryonic development, given the lack of bold detrimental effects observed in the mouse model.

STUDY FUNDING/COMPETING INTEREST(S)

This work was supported by the Deutsche Forschungsgemeinschaft (BO 2540/4-1 and SCHL 394/9-1) and by the Nederlandse Organisatie voor Wetenschappelijk Onderzoek (S.L.G.); Bilateral grant NWO-DFG 63-258. None of the authors has any conflict of interest to declare.

TRIAL REGISTRATION NUMBER

Not applicable.

Birthweight and placental weight; do changes in culture media used for IVF matter? Comparisons with spontaneous pregnancies in the corresponding time periods

STUDY QUESTION

Have changes in culture media used for IVF resulted in changes in offspring birthweight or placental weight that differed from the trends in offspring from spontaneous conceptions during the corresponding time periods?

SUMMARY ANSWER

Changes in culture media used for IVF were associated with significant differences in offspring birthweight and in placental weight to birthweight ratio when compared with the trend in offspring from spontaneous conceptions during the time periods.

WHAT IS KNOWN ALREADY

The effect of culture media used for IVF on offspring birthweight has varied between studies. There is a large variation in birthweight between newborns, and birthweight may vary across populations and over time. Such variations may therefore have influenced previous results.

STUDY DESIGN, SIZE, DURATION

We included all singleton births from IVF at one treatment center in Norway during the years 1999-2011(n = 2435) and all singleton births from spontaneous conceptions in Norway during the same years (n = 698 359).

PARTICIPANTS/MATERIALS, SETTING, METHODS

Three different media were used for embryo culture; Medicult Universal IVF (1999 through 2007, n = 1584), Medicult ISM1 (2008 until 20 September 2009, n = 402) and Vitrolife G-1 PLUS (21 September 2009 through 2011, n = 449). We estimated mean birthweight and placental weight in IVF pregnancies by culture media. We also estimated mean weights in IVF and in spontaneous pregnancies by year of birth. Thereafter, we studied whether the changes in mean weights in IVF pregnancies differed from the changes in weight in spontaneous pregnancies in the periods corresponding to culture media changes by applying a grouped difference-in-difference analysis. Adjustments were made for parity, maternal age and gestational age at birth.

MAIN RESULTS AND THE ROLE OF CHANCE

In singleton offspring from IVF the mean birthweight was 3447.6 g with Medicult Universal, 3351.7 g with Medicult ISM1 and 3441.4 g with Vitrolife G-1 PLUS (P < 0.05). The corresponding mean placental weights were 684.1, 693.4 and 704.3 g (P < 0.05). In offspring from spontaneous conceptions the mean birthweight decreased (56.9 g) and the placental weight increased (9.3 g) during the study period. The adjusted difference in birthweight in offspring from IVF decreased with 35.0 g by the change from Medicult Universal to Medicult ISM1 (P = 0.16) and increased with 79.9 g by the change from Medicult ISM1 to Vitrolife G-1 PLUS (P = 0.01) when compared with changes in offspring after spontaneous conceptions, We also found a significant increase in placental weight in relation to birthweight by the change from Medicult ISM1 to Vitrolife G-1 PLUS (P = 0.02).

LIMITATIONS, REASONS FOR CAUTION

There may be underlying factors that have influenced both birthweight and the use of culture media in IVF pregnancies. Lack of adjustment for such possible factors may have biased our results.

WIDER IMPLICATIONS OF THE FINDINGS

We found a significant effect of culture media used for IVF on birthweight and on placental weight in relation to birthweight. Also the population changes over time should encourage identification of factors in very early embryonic life that may influence birthweight and placental weight.

STUDY FUNDING/COMPETING INTERESTS

We received funding from the South-Eastern Regional Health Authority in Norway for this study (2011136-2012). None of the authors has any conflicts of interest to declare.