Assisted reproductive technology: an overview of Cochrane Reviews

The Effect of Endometrial Thickness on Pregnancy, Maternal, and Perinatal Outcomes of Women in Fresh Cycles After IVF/ICSI: A Systematic Review and Meta-Analysis

BACKGROUND

Thin endometrium on ovulation triggering day is associated with impaired pregnancy outcomes in women after in vitro fertilization/intracytoplasmic sperm injection (IVF/ICSI), but the role of thick endometrium on pregnancy outcomes remains controversial. Moreover, there has been insufficient evidence currently to analyze the influence of endometrial thickness (EMT) on obstetric complications and perinatal outcomes. Thus, we performed this meta-analysis to evaluate the effect of EMT on pregnancy, maternal, and perinatal outcomes in an enlarged sample size.

METHODS

The databases Pubmed, Embase, Cochrane Libraries, and Web of Science were searched for English articles evaluating the correlation between EMT and pregnancy, maternal, or perinatal outcomes in women who underwent IVF/ICSI. We included studies that depicted a clear definition of outcomes and EMT grouping on ovulation triggering day. The EMT effect was analyzed in fresh cycle. Qualities of studies were assessed by the Newcastle-Ottawa Scale (NOS). Odds ratios (ORs) and weighted mean difference (WMD) with 95% confidence intervals (CIs) were calculated for analyzing dichotomous and continuous outcomes respectively, under a fixed or random effect model.

RESULTS

A total of 22 pieces of literature were included for the final meta-analysis. A decreased trend towards pregnancy outcomes was observed, such as live birth rate (LBR), clinical pregnancy rate (CPR), and implantation rate (IR) in the thin endometrium groups (EMT <7 mm). In contrast, thick endometrium (EMT >14 mm) had no effect on pregnancy outcomes compared to medium EMT groups (EMT 7-14 mm). Moreover, thin endometrium (EMT <7.5 mm) enhanced the incidence of hypertensive disorders of pregnancy (HDP) and small-for-gestational-age (SGA) infants, and decreased the birthweight (BW) of babies.

CONCLUSIONS

Our studies indicated that thin endometrium not only had detrimental effect on pregnancy outcomes, but also increased the risk of HDP in women and SGA of babies, or decreased BW of babies. The thick endometrium does not have an adverse effect on IVF outcomes. Therefore, patients need to be informed on possible obstetric complications and perinatal outcomes caused by thin endometrium and are encouraged to actively cooperate with perinatal care.

SYSTEMATIC REVIEW REGISTRATION

(https://www.crd.york.ac.uk/PROSPERO/display_record.php?RecordID=242637), identifier CRD42021242637.

Risk factors for resignation from work after starting infertility treatment among Japanese women: Japan-Female Employment and Mental health in Assisted reproductive technology (J-FEMA) study

OBJECTIVE

To elucidate the risk factors associated with resignation from work of Japanese women undergoing infertility treatment.

METHODS

A total of 1727 female patients who attended a private fertility clinic in Japan participated in the Japan-Female Employment and Mental health in Assisted reproductive technology study. Questions related to demographic, clinical and socioeconomic characteristics were employed in the questionnaire. Out of the 1727 patients, 1075 patients who were working at the time of initiating infertility treatment and felt infertility treatment incompatible with work were included in the analysis. Risk factors for resignation were assessed by using multivariable logistic regression models.

RESULTS

Among 1075 working women who started infertility treatment, 179 (16.7%) subsequently resigned. Multivariable-adjusted ORs for resignation in those with lower educational background and infertility for ≥2 years were 1.58 (95% CI: 1.07 to 2.34) and 1.82 (95% CI: 1.15 to 2.89), respectively. The OR for resignation in non-permanent workers undergoing infertility treatment was 2.65 (95% CI: 1.61 to 4.37). While experiencing harassment in the workplace approached significance, lack of support from the company was significantly associated with resignation after starting infertility treatment, with ORs of 1.71 (95% CI: 0.98 to 2.99) and 1.91 (95% CI: 1.28 to 2.86), respectively.

CONCLUSION

One-sixth of women resigned after starting infertility treatments. It was found that factors related to education, infertility duration and work environment were significantly associated with resignation. Reducing the physical and psychological burden endured by women, for example, by increasing employer-provided support, is vitally important in balancing infertility treatment with maintenance of work life.

Reproductive Outcomes of Single Embryo Transfer in Women with Previous Cesarean Section

The aim of this study is to evaluate the reproductive outcomes of patients with previous cesarean section (CS) undergoing single-embryo transfer (SET). A total of 5479 patients previously underwent CS or vaginal delivery (VD) were included. The patients with previous CS included single/double cleavage (SCT/DCT), single/double blastocyst stage embryo transfer (SBT/DBT). The comparison of reproductive outcomes between CS and VD, SET, and double-embryo transfer of CS was conducted. The main outcome measures included clinical pregnancy rate (CPR), multiple pregnancy rate (MPR), live birth rate (LBR), and cumulative live birth rate (CLBR). There were no differences in CPR and LBR between patients previously underwent CS and VD, and the preterm birth rate of multiple births in patients underwent CS were significantly higher than underwent VD. As for patients underwent CS, the CPR, MPR, and LBR were lower in patients treated with SCT than DCT in IVF/ICSI cycles. The CPR and LBR of patients treated with SCT were not statistically different compared with DCT and SBT when patients' age were younger than 35 years in FET cycles, and the MPR of patients treated with SCT was lower. The CPR and LBR of patients treated with SCT were lower than DCT/SBT when patients' age were 35 years or older in FET cycles. The CPR, LBR, and CLBR of patients treated with SBT were not lower than DCT in IVF/ICSI-ET, FET, and complete cycles, but the MPR was lower. Reducing the number of embryos transferred should be considered seriously for CS. SCT under the 35 years of FET cycles is feasible. SBT is an effective strategy to reduce MPR of IVF/ICSI, FET, and complete cycles regardless of overall or age stratification.

Impact of vitamin D on human embryo implantation-a prospective cohort study in women undergoing fresh embryo transfer

OBJECTIVE

To measure free and total 25-hydroxyvitamin D [25(OH)D] immediately before embryo transfer and analyze its association with early pregnancy outcome parameters such as biochemical pregnancy, implantation rate, and clinical pregnancy rates in women undergoing fresh embryo transfer after their first ovarian hyperstimulation.

DESIGN

Prospective cohort study.

SETTING

Academically affiliated private fertility center.

PATIENT(S)

A total of 2,569 women undergoing fresh embryo transfer after ovarian hyperstimulation.

INTERVENTIONS(S)

None.

MAIN OUTCOME MEASURE(S)

The study end points were biochemical pregnancy rate, implantation rate, clinical pregnancy rate, ectopic pregnancy rate, early miscarriages, and ongoing pregnancy rate. Free and total 25(OH)D concentrations were measured 1 day before embryo transfer.

RESULT(S)

Total 25(OH)D correlated with free 25(OH)D. Total and free 25(OH)D serum concentrations were similar in those patients reaching and not reaching the study outcomes (biochemical pregnancy rate, implantation rate, clinical pregnancy rate, ectopic pregnancy rate, early miscarriages, and ongoing pregnancy rate). There was likewise no statistical difference when analyzing the frequency of all study outcomes in quintiles of either total or free 25(OH)D. In addition, the study population was divided into three groups according to the total vitamin D status based on clinical practice guideline. All outcomes were similar in women with adequate, insufficient, and deficient total 25(OH)D. Multiple linear regression analysis considering confounding likewise indicated no association of free or total vitamin D with any of the study outcomes.

CONCLUSION(S)

Neither free nor total 25(OH)D concentration at embryo transfer was associated with successful embryo implantation in women undergoing fresh transfer after ovarian hyperstimulation.

Genetics in human reproduction

Approximately 50% of the causes of infertility are of genetic origin. The objective of this study was to analyze the role of genetics in human reproduction by reviewing the main genetic causes of infertility and the use of preimplantation genetic testing in Brazil. This literature review comprised articles in English and Portuguese published on databases PubMed, Scielo, and Bireme from 1990 to 2019. Randomized clinical trials and specialized guidelines were given preference whenever possible. Genetic cause can be traced back to up to 20% of the cases of severe azoospermia or oligozoospermia. Subjects with these conditions are good candidates for genetic screening. In women, genetic causes of infertility (fragile X syndrome, X-trisomy, and Turner's syndrome, some of which diagnosed with karyotyping) culminate with premature ovarian failure. Genetic screening helps advise couples of the risk of experiencing early reproductive capacity loss and of the chances of their offspring carrying genetic disorders. In addition to enhancing the prevention of serious diseases in the offspring of couples at increased risk of genetic diseases, preimplantation genetic screening improves the success rates of assisted reproduction procedures by allowing the selection of euploid embryos for transfer. The interface between genetics and human reproduction has gained significant relevance, but discussions are still needed on which procedures are clinically and ethically acceptable and how they should be regulated.

Does coenzyme Q10 supplementation improve fertility outcomes in women undergoing assisted reproductive technology procedures? A systematic review and meta-analysis of randomized-controlled trials

OBJECTIVE

Increased oxidative stress has been identified as a pathogenetic mechanism in female infertility. However, the effect of specific antioxidants, such as coenzyme Q10 (CoQ10), on the outcomes after assisted reproductive technologies (ART) has not been clarified. The aim of this study was to systematically review and meta-analyze the best available evidence regarding the effect of CoQ10 supplementation on clinical pregnancy (CPR), live birth (LBR), and miscarriage rates (MR) compared with placebo or no-treatment in women with infertility undergoing ART.

METHODS

A comprehensive literature search was conducted in PubMed (MEDLINE), Cochrane, and Scopus, from inception to March 2020. Data were expressed as odds ratio (OR) with 95% confidence intervals (CI). The I2 index was employed for heterogeneity.

RESULTS

Five randomized-controlled trials fulfilled eligibility criteria (449 infertile women; 215 in CoQ10 group and 234 in placebo/no treatment group). Oral supplementation of CoQ10 resulted in an increase of CPR when compared with placebo or no-treatment (28.8% vs. 14.1%, respectively; OR 2.44, 95% CI 1.30-4.59, p = 0.006; I2 32%). This effect remained significant when women with poor ovarian response and polycystic ovarian syndrome were analyzed separately. No difference between groups was observed regarding LBR (OR 1.67, 95% CI 0.66-4.25, p = 0.28; I2 34%) and MR (OR 0.61, 95% CI 0.13-2.81, p = 0.52; I2 0%).

CONCLUSIONS

Oral supplementation of CoQ10 may increase CPR when compared with placebo or no-treatment, in women with infertility undergoing ART procedures, without an effect on LBR or MR.

Comparison of general maternal and neonatal conditions and clinical outcomes between embryo transfer and natural conception

Background

To examine the differences between pregnant women who underwent embryo transfer (ET) and those who conceived naturally, as well as differences in their respective babies, and to determine the causes for these differences, to provide recommendations for women who are planning to undergo ET.

Methods

A retrospective cohort study was performed of women who had received ET and those who had natural conception (NC) who received medical services during pregnancy and had their babies delivered at the Shunde Women and Children’s Hospital of Guangdong Medical University, China between January 2016 and December 2018. In line with the requirements of the ethics committee, before the formal investigation, we first explained the content of the informed consent of the patient to the patient, and all the subjects included agreed to the content of the informed consent of the patient. Respondents agreed to visit and analyze their medical records under reasonable conditions. Each case in an ET group of 321 women was randomly matched with three cases of NC (963 cases) who delivered on the same day. The demographic information, past history, pregnancy and delivery history, and maternal and neonatal outcomes of the two groups were compared using univariate analysis.

Results

Age, duration of hospitalization, number of pregnancies, number of miscarriages, induced abortion, ectopic pregnancy, gestational diabetes mellitus, preeclampsia, gestational anemia, pregnancy risk, mode of fetal delivery, and number of births were significantly different between the two groups (all P < 0.05). However, there were no significant differences in the disease, allergy, infection and blood transfusion histories of the pregnant women, or differences in prevalence of gestational hypothyroidism, gestational respiratory infection, premature rupture of membrane, placental abruption, fetal death, stillbirth, amniotic fluid volume and amniotic fluid clarity between the two groups (all P > 0.05). The percentages for low birth weight and premature birth were significantly higher in the ET group than in the NC group. In contrast, infant gender and prevalence of fetal macrosomia, fetal anomaly, neonatal asphyxia, and extremely low birth weight were not significantly different between the two groups (all P > 0.05).

Conclusions

The clinical outcomes of mothers and the birth status of infants were better in the NC group than in the ET group. Maternal health must be closely monitored and improved in the ET group to reduce the incidence of gestational comorbidity and enhance the quality of fetal life.

Early Life Oxidative Stress and Long-Lasting Cardiovascular Effects on Offspring Conceived by Assisted Reproductive Technologies: A Review

Assisted reproductive technology (ART) has rapidly developed and is now widely practised worldwide. Both the characteristics of ART (handling gametes/embryos in vitro) and the infertility backgrounds of ART parents (such as infertility diseases and unfavourable lifestyles or diets) could cause increased oxidative stress (OS) that may exert adverse influences on gametogenesis, fertilisation, and foetation, even causing a long-lasting influence on the offspring. For these reasons, the safety of ART needs to be closely examined. In this review, from an ART safety standpoint, the origins of OS are reviewed, and the long-lasting cardiovascular effects and potential mechanisms of OS on the offspring are discussed.

Sex effects across the lifespan in women with multiple sclerosis

Multiple sclerosis (MS) is an autoimmune inflammatory demyelinating central nervous system disorder that is more common in women, with onset often during reproductive years. The female:male sex ratio of MS rose in several regions over the last century, suggesting a possible sex by environmental interaction increasing MS risk in women. Since many with MS are in their childbearing years, family planning, including contraceptive and disease-modifying therapy (DMT) counselling, are important aspects of MS care in women. While some DMTs are likely harmful to the developing fetus, others can be used shortly before or until pregnancy is confirmed. Overall, pregnancy decreases risk of MS relapses, whereas relapse risk may increase postpartum, although pregnancy does not appear to be harmful for long-term prognosis of MS. However, ovarian aging may contribute to disability progression in women with MS. Here, we review sex effects across the lifespan in women with MS, including the effect of sex on MS susceptibility, effects of pregnancy on MS disease activity, and management strategies around pregnancy, including risks associated with DMT use before and during pregnancy, and while breastfeeding. We also review reproductive aging and sexual dysfunction in women with MS.

The effects of hyaluronate-containing medium on human embryo attachment to endometrial epithelial cells in vitro

STUDY QUESTION

Does embryo transfer medium containing hyaluronate (HA) promote the attachment phase of human embryo implantation?

SUMMARY ANSWER

HA-containing medium does not promote human blastocyst attachment to endometrial epithelial cells in vitro.

WHAT IS KNOWN ALREADY

Embryo transfer media containing high concentrations of HA are being used to increase implantation and live birth rates in IVF treatment, although the mechanism of action is unknown.

STUDY DESIGN, SIZE, DURATION

Expression of HA-interacting genes in frozen-thawed oocytes/embryos was assessed by microarray analysis (n = 21). Fresh and frozen human blastocysts (n = 98) were co-cultured with human endometrial epithelial Ishikawa cell layers. Blastocyst attachment and the effects of a widely used HA-containing medium were measured.

PARTICIPANTS/MATERIALS, SETTING, METHODS

Human embryos surplus to treatment requirements were donated with informed consent from several ART centres. Blastocyst-stage embryos were transferred at day 6 to confluent Ishikawa cell layers; some blastocysts were artificially hatched. Blastocyst attachment was monitored from 1 to 48 h, and the effects of blastocyst pre-treatment for 10 min with HA-containing medium were determined.

MAIN RESULTS AND THE ROLE OF CHANCE

Human embryos expressed the HA receptor genes CD44 and HMMR, hyaluronan synthase genes HAS1–3, and hyaluronidase genes HYAL1–3, at all stages of preimplantation development. Attachment of partially hatched blastocysts to Ishikawa cells at 24 and 48 h was related to trophectoderm grade (P = 0.0004 and 0.007, respectively, n = 34). Blastocysts of varying clinical grades that had been artificially hatched were all attached within 48 h (n = 21). Treatment of artificially hatched blastocysts with HA-containing medium did not significantly affect attachment at early (1–6 h) or late (24 and 48 h) time points, compared with control blastocysts (n = 43).

LIMITATIONS, REASONS FOR CAUTION

Using an adenocarcinoma-derived cell line to model embryo-endometrium attachment may not fully recapitulate in vivo interactions. The high levels of blastocyst attachment seen with this in vitro model may limit the sensitivity with which the effects of HA can be observed.

WIDER IMPLICATIONS OF THE FINDINGS

Morphological trophectoderm grade can be correlated with blastocyst attachment in vitro. HA-containing medium may increase pregnancy rates by mechanisms other than promoting blastocyst attachment to endometrium.

STUDY FUNDING/COMPETING INTEREST(S)

This work was funded by a grant from the Wellbeing of Women, the NIHR Local Comprehensive Research Network and NIHR Manchester Clinical Research Facility, the Department of Health Scientist Practitioner Training Scheme, and the Ministry of Higher Education, The State of Libya. None of the authors has any conflict of interest to declare.

The Surgical Benefit of Hysterolaparoscopy in Endometriosis-Related Infertility: A Single Centre Retrospective Study with a Minimum 2-Year Follow-Up

AIM

This study examined the fertility performance of women after combined hysterolaparoscopic surgical management of endometriosis. Design: This study is a hospital-based retrospective review.

MATERIALS AND METHODS

Data collected from the records of all patients presented with endometriosis-related infertility using a checklist designed for the purpose. Result: A total of 81.3% (370/455) of women who have had the desire to have children became pregnant during the study period after the surgery. Of those who became pregnant, all three-hundred-forty-seven patients were followed to the end of their pregnancies. A successful live birth occurred in 94.2% (327/347) of individuals, and pregnancy loss occurred in 5.8% (20/347). The mean patient age was 34.1 ± 4.1 years, and the average duration of infertility was 3.4 ± 3.3 years. Pregnancy occurred spontaneously in 39.5% (146/370) of patients, after artificial insemination (AIH) in 3.8% (14/370) of women, and after in vitro fertilization-embryo transfer (IVF-ET) in 56.8% (210/370) of cases. Patients aged ≤ 35 years had a higher chance of conception post-surgery-84% versus 77%, respectively (p = 0.039). Based on the modes of pregnancy, the timely introduction of an assisted reproductive technique (ART) demonstrated a significant effect on fertility performance postsurgery. Comparatively, this effect was 91.3% vs. 74.1% among the ≤35- and >35-year-old age groups, respectively. There was no significant difference in reproductive performance based on stages of endometriosis, nor in the other parameters evaluated. Conclusion: Our data are consistent with previous clinical studies regarding the management options of endometriosis-related infertility. Overall, the combined hysterolaparoscopy treatment is a very effective and reliable procedure, and is even more effective when combined with ART. It enhances women's wellbeing and quality of life, and significantly improves reproductive performance.

Acupuncture and Chinese Herbal Medicine Effects on Assisted Reproductive Technology: Six Cases and Their Clinical Significance

Background: Assisted reproductive technology (ART) is the routine treatment for infertility. The success rate for individual sessions is generally not high, and many patients need to undergo several cycles. To increase their chances of success, many patients turn to acupuncture to complement ART. Many clinical trials of acupuncture helping in vitro fertilization (IVF) have focused only on IVF-embryo transfer (ET). In some difficult cases, when even IVF cannot be offered, acupuncture and Chinese herbs can improve the patients' conditions to reach a level at which ART can be successful. Cases: Six cases showed how acupuncture and Traditional Chinese Medicine (TCM), using Chinese herbs, can make IVF possible in difficult cases and how they can also help prevent miscarriage afterward. The cases included patients with amenorrhea, sperm disorders, polycystic ovary syndrome, diminished ovarian reserve (DOR), tubal blockage, premenopause, and premature ovarian insufficiency. Results: Acupuncture and Chinese herbs worked together to help make ART possible or easier. The ART used for these patients included intrauterine insemination, IVF, IVF with a donor egg, and introcytoplasmic sperm injection. In 3 cases, IVF was not initially successful but was successful after TCM treatment. Conclusions: These 6 cases demonstrated the positive effect of a combined approach, using acupuncture and herbs to reduce DOR and regulate hormonal disorders, creating sustainable environments for conceiving and maintaining pregnancy, thus, translating into clinical success. Clinical observation of these cases sheds new light on designing future clinical trials and practice of TCM for practitioners who provide infertility treatments.

C-kit signaling promotes human pre-implantation 3PN embryonic development and blastocyst formation

BACKGROUND

Although in vitro culture system has been optimized in the past few decades, the problem of few or no high quality embryos has been still not completely solved. Accordingly, fully understanding the regulatory mechanism of pre-implantation embryonic development would be beneficial to further optimize the in vitro embryo culture system. Recent studies have found the expression of c-kit in mouse embryo and its promotion effects on mouse embryonic development. However, it is unclear the expression, the role and the related molecular regulatory mechanism of c-kit in human pre-implantation embryo development. Therefore, the present study is to determine whether c-kit is expressed in human pre-implantation embryos, and to investigate the possible regulatory mechanism of c-kit signaling in the process of embryonic development.

METHODS

The present study includes human immature oocytes and three pronucleus (3PN) embryos collected from 768 women (28-32 ages) undergoing IVF, and normal 2PN embryos collected from ICR mice. Samples were distributed randomly into three different experimental groups: SCF group: G-1™ (medium for culture of embryos from the pro-nucleate stage to day 3) or G-2™ (medium for culture of embryos from day3 to blastocyst stage) + HSA (Human serum album) solution + rhSCF; SCF + imanitib (c-kit inhibitor) group: G-1™ or G-2™ + HSA solution + rhSCF + imanitib; SCF + U0126 (MEK/ERK inhibitor) group: G-1™ or G-2™ + HSA solution + rhSCF + U0126; Control group: G-1™ or G-2™ + HSA solution + PBS; The rate of good quality embryos at day 3, blastulation at day 6 and good quality blastulation at day 6 were analysis. RT-PCR, western blot and immunofluorescence staining were applied to detect the target genes and proteins in samples collected from human or mice, respectively.

RESULTS

c-kit was expressed ubiquitously in all human immature oocytes, 3PN embryos and 3PN blastocysts. In the experiment of human 3PN embryos, compared with other groups, SCF group showed obviously higher rate of good quality at day 3, better rate of blastocyst formation at day 6 and higher rate of good quality blastocyst formation at day 6. Furthermore, we observed a higher ETV5 expression in SCF group than that in other groups. Similar results were also found in animal experiment. Interestingly, we also found a higher phosphorylation level of MEK/ERK signal molecule in mice embryos from SCF group than those from other groups. Moreover, inhibition of MEK/ERK signaling would remarkably impeded the mice embryonic development, which might be due to the reduced ETV5 expression.

CONCLUSIONS

The present study firstly revealed that c-kit signaling might promote the human pre-implantation embryonic development and blastocyst formation by up-regulating the expression of ETV5 via MEK/ERK pathway. Our findings provide a new idea for optimizing the in vitro embryo culture condition during ART program, which is beneficial to obtain high quality embryos for infertile patients.

Assisted reproductive technologies are associated with limited epigenetic variation at birth that largely resolves by adulthood

More than 7 million individuals have been conceived by Assisted Reproductive Technologies (ART) and there is clear evidence that ART is associated with a range of adverse early life outcomes, including rare imprinting disorders. The periconception period and early embryogenesis are associated with widespread epigenetic remodeling, which can be influenced by ART, with effects on the developmental trajectory in utero, and potentially on health throughout life. Here we profile genome-wide DNA methylation in blood collected in the newborn period and in adulthood (age 22–35 years) from a unique longitudinal cohort of ART-conceived individuals, previously shown to have no differences in health outcomes in early adulthood compared with non-ART-conceived individuals. We show evidence for specific ART-associated variation in methylation around birth, most of which occurred independently of embryo culturing. Importantly, ART-associated epigenetic variation at birth largely resolves by adulthood with no direct evidence that it impacts on development and health.

Use of Assisted Reproductive Technologies (ART) is increasing globally but their impact on long term health remains unclear. Here the authors show that ART-conceived individuals show variation in epigenetic profile at birth that largely resolves by adulthood, with no evidence of an impact on long term outcomes.

Correlations between embryo morphokinetic development and maternal age: Results from an intracytoplasmic sperm injection program

Objective

It is widely accepted that aging decreases women’s fertility capacity. The aim of this study was to assess correlations between maternal age and the morphokinetic parameters and cleavage pattern of embryos.

Methods

The morphokinetics of embryos derived from women <30, 30–35, 36–40, and >40 years of age were compared retrospectively in terms of time of second polar body extrusion, time of pronuclei appearance, time of pronuclei fading, and time of two to eight discrete cells (t2–t8). Furthermore, abnormal cleavage patterns such as uneven blastomeres at the two-cell stage, cell fusion (Fu), and trichotomous mitoses (TM) were assessed.

Results

Only t5 occurred later in women aged 36–40 and >40 years when compared with those aged <30 and 30–35 years (p<0.001). Other morphokinetic timing parameters, as well the presence of uneven blastomeres, were comparable between the groups (p>0.05). However, Fu and TM were more common in women aged >40 years than in younger women (p<0.001).

Conclusion

Maternal age was correlated with the cleavage pattern of embryos. Therefore, evaluating embryo morphokinetics may contribute to optimal embryo selection, thereby increasing fertility in patients with advanced maternal age.

Interventions during pregnancy to prevent preterm birth: an overview of Cochrane systematic reviews

BACKGROUND

Preterm birth (PTB) is a major factor contributing to global rates of neonatal death and to longer-term health problems for surviving infants. Both the World Health Organization and the United Nations consider prevention of PTB as central to improving health care for pregnant women and newborn babies. Current preventative clinical strategies show varied efficacy in different populations of pregnant women, frustrating women and health providers alike, while researchers call for better understanding of the underlying mechanisms that lead to PTB.

OBJECTIVES

We aimed to summarise all evidence for interventions relevant to the prevention of PTB as reported in Cochrane systematic reviews (SRs). We intended to highlight promising interventions and to identify SRs in need of an update.

METHODS

We searched the Cochrane Database of Systematic Reviews (2 November 2017) with key words to capture any Cochrane SR that prespecified or reported a PTB outcome. Inclusion criteria focused on pregnant women without signs of preterm labour or ruptured amniotic membranes. We included reviews of interventions for pregnant women irrespective of their risk status. We followed standard Cochrane methods.We applied GRADE criteria to evaluate the quality of SR evidence. We assigned graphic icons to classify the effectiveness of interventions as: clear evidence of benefit; clear evidence of harm; clear evidence of no effect or equivalence; possible benefit; possible harm; or unknown benefit or harm. We defined clear evidence of benefit and clear evidence of harm to be GRADE moderate- or high-quality evidence with a confidence interval (CI) that does not cross the line of no effect. Clear evidence of no effect or equivalence is GRADE moderate- or high-quality evidence with a narrow CI crossing the line of no effect. Possible benefit and possible harm refer to GRADE low-quality evidence with a clear effect (CI does not cross the line of no effect) or GRADE moderate- or high-quality evidence with a wide CI. Unknown harm or benefit refers to GRADE low- or very low-quality evidence with a wide CI.

MAIN RESULTS

We included 83 SRs; 70 had outcome data. Below we highlight key results from a subset of 36 SRs of interventions intended to prevent PTB.

OUTCOME

preterm birthClear evidence of benefitFour SRs reported clear evidence of benefit to prevent specific populations of pregnant women from giving birth early, including midwife-led continuity models of care versus other models of care for all women; screening for lower genital tract infections for pregnant women less than 37 weeks' gestation and without signs of labour, bleeding or infection; and zinc supplementation for pregnant women without systemic illness. Cervical cerclage showed clear benefit for women with singleton pregnancy and high risk of PTB only.Clear evidence of harmNo included SR reported clear evidence of harm.No effect or equivalenceFor pregnant women at high risk of PTB, bedrest for women with singleton pregnancy and antibiotic prophylaxis during the second and third trimester were of no effect or equivalent to a comparator.Possible benefitFour SRs found possible benefit in: group antenatal care for all pregnant women; antibiotics for pregnant women with asymptomatic bacteriuria; pharmacological interventions for smoking cessation for pregnant women who smoke; and vitamin D supplements alone for women without pre-existing conditions such as diabetes.Possible harmOne SR reported possible harm (increased risk of PTB) with intramuscular progesterone, but this finding is only relevant to women with multiple pregnancy and high risk of PTB. Another review found possible harm with vitamin D, calcium and other minerals for pregnant women without pre-existing conditions.

OUTCOME

perinatal deathClear evidence of benefitTwo SRs reported clear evidence of benefit to reduce pregnant women's risk of perinatal death: midwife-led continuity models of care for all pregnant women; and fetal and umbilical Doppler for high-risk pregnant women.Clear evidence of harmNo included SR reported clear evidence of harm.No effect or equivalenceFor pregnant women at high risk of PTB, antibiotic prophylaxis during the second and third trimester was of no effect or equivalent to a comparator.Possible benefitOne SR reported possible benefit with cervical cerclage for women with singleton pregnancy and high risk of PTB.Possible harmOne SR reported possible harm associated with a reduced schedule of antenatal visits for pregnant women at low risk of pregnancy complications; importantly, these women already received antenatal care in settings with limited resources.

OUTCOMES

preterm birth and perinatal deathUnknown benefit or harmFor pregnant women at high risk of PTB for any reason including multiple pregnancy, home uterine monitoring was of unknown benefit or harm. For pregnant women at high risk due to multiple pregnancy: bedrest, prophylactic oral betamimetics, vaginal progesterone and cervical cerclage were all of unknown benefit or harm.

AUTHORS' CONCLUSIONS

Implications for practiceThe overview serves as a map and guide to all current evidence relevant to PTB prevention published in the Cochrane Library. Of 70 SRs with outcome data, we identified 36 reviews of interventions with the aim of preventing PTB. Just four of these SRs had evidence of clear benefit to women, with an additional four SRs reporting possible benefit. No SR reported clear harm, which is an important finding for women and health providers alike.The overview summarises no evidence for the clinically important interventions of cervical pessary, cervical length assessment and vaginal progesterone because these Cochrane Reviews were not current. These are active areas for PTB research.The graphic icons we assigned to SR effect estimates do not constitute clinical guidance or an endorsement of specific interventions for pregnant women. It remains critical for pregnant women and their healthcare providers to carefully consider whether specific strategies to prevent PTB will be of benefit for individual women, or for specific populations of women.Implications for researchFormal consensus work is needed to establish standard language for overviews of reviews and to define the limits of their interpretation.Clinicians, researchers and funders must address the lack of evidence for interventions relevant to women at high risk of PTB due to multiple pregnancy.