Is assisted reproduction associated with abnormal placentation?

Placentation and complications of ART pregnancy. An update on the different possible etiopathogenic mechanisms involved in the development of obstetric complications

INTRODUCTION

Infertile couples' percentage is increasing all over the world, especially in Italy, with high number of children born in our country through assisted reproductive techniques (ART). However, pregnancies obtained by ART have increased potential obstetrical risks which could be caused by fetus-placenta unit development, most of all due to placentation's evolution. These can be reassumed into miscarriage, chromosomal abnormalities, preterm delivery, multiple pregnancy, IUGR, placenta previa, abruptio placentae, preeclampsia and hypertensive disorders, postpartum hemorrhage.

METHODS

The aim of this article is to evaluate hypothetic mechanism involved in placentation process and in the etiopathology of ART pregnancies disorders, giving an updating overview of different etiopathogenetic pathways and features. On this scenario, we create an updated review about the etiopathogenesis of abnormal placentation in ART pregnancies.

RESULTS

Several features and different etiopathogenetic characteristic might impact differently such as advanced maternal age, poor ovarian reserve, oocyte quality and causes of subfertility themselves, and the ART techniques itself, as hormonal medical treatments and laboratory techniques such as gamete and embryo laboratory culture, cryopreservation versus fresh ET, number of embryos transferred.

CONCLUSION

To further explore the molecular mechanisms behind placentation in ART pregnancies, further studies are necessary to gain a better understanding of the various aspects involved, particularly those which are not fully comprehended. This could prove beneficial to clinicians in both ART care and obstetric care, as it could help to stratify obstetrical risk and decrease complications in women undergoing ART, as well as perinatal disorders in their children. Correct placentation is essential for a successful pregnancy for both mother and baby.

Long-term health risk of offspring born from assisted reproductive technologies

Since the world's first in vitro fertilization baby was born in 1978, there have been more than 8 million children conceived through assisted reproductive technologies (ART) worldwide, and a significant proportion of them have reached puberty or young adulthood. Many studies have found that ART increases the risk of adverse perinatal outcomes, including preterm birth, low birth weight, small size for gestational age, perinatal mortality, and congenital anomalies. However, data regarding the long-term outcomes of ART offspring are limited. According to the developmental origins of health and disease theory, adverse environments during early life stages may induce adaptive changes and subsequently result in an increased risk of diseases in later life. Increasing evidence also suggests that ART offspring are predisposed to an increased risk of non-communicable diseases, such as malignancies, asthma, obesity, metabolic syndrome, diabetes, cardiovascular diseases, and neurodevelopmental and psychiatric disorders. In this review, we summarize the risks for long-term health in ART offspring, discuss the underlying mechanisms, including underlying parental infertility, epigenetic alterations, non-physiological hormone levels, and placental dysfunction, and propose potential strategies to optimize the management of ART and health care of parents and children to eliminate the associated risks. Further ongoing follow-up and research are warranted to determine the effects of ART on the long-term health of ART offspring in later life.

Comparison of maternal, fetal, obstetric and neonatal outcomes for 234 triplet pregnancies conceived in vivo versus IVF and ICSI conceptions

RESEARCH QUESTION

Is there a difference in maternal, fetal, obstetric and neonatal outcomes for triplet pregnancies when comparing in vivo conceptions with those conceived by assisted reproductive technology (ART)?

DESIGN

This single-centre, retrospective cohort study included all triplet pregnancies followed up at La Paz University Hospital, Madrid between 2000 and 2022. The characteristics of the pregnant women, and maternal, fetal, obstetric and perinatal outcomes were examined. Univariate and multivariate statistical analyses were performed.

RESULTS

In total, 234 triplet pregnancies were analysed: 92 in the natural and assisted insemination conception group (in-vivo conception) and 142 in the in vitro fertilization and intracytoplasmic sperm injection conception group (ART conception). ART triplet pregnancies were more common between 2000 and 2010 (P = 0.003). The percentage of monochorionic triamniotic pregnancies was significantly higher (P = 0.02) in the in-vivo conception group, and the percentage of dichorionic triamniotic pregnancies was significantly higher (P = 0.003) in the ART conception group. After adjusting for confounders, intrauterine growth restriction (IUGR) remained significantly more common in the ART conception group (adjusted odds ratio 8.65, 95% CI 1.66-45.03; P = 0.01). Differences in maternal age (P = 0.61), threatened preterm labour (P = 0.10), Apgar score ≤5 at 5 min (P = 0.99), umbilical cord pH <7.20 (P = 0.99) and fetal death (P = 0.99) disappeared after adjustment for confounders.

CONCLUSION

ART triplet pregnancies had a higher rate of IUGR than in vivo triplet pregnancies. This could be related to higher maternal age, and higher rates of Apgar score ≤5 at 5 min and umbilical cord pH <7.20 in these pregnancies. In these cases, placental examination could provide valuable information.

Programmed frozen embryo transfer cycles are associated with a higher risk of abnormal placental development: a retrospective cohort study of singleton live births

Introduction

Abnormal placental development can lead to adverse outcomes for both mother and fetus. The effect of different types of endometrium preparation regimens of frozen-thawed cycles on the placental development features associated with the perinatal outcomes remains unclear. Hence, we conducted a retrospective cohort study to assess the impact of specific endometrial preparation regimens on placenta-mediated pregnancy complications in singleton live births.

Methods

A retrospective cohort study was conducted evaluating data of all singleton live births both conceived naturally or by in vitro fertilization (IVF) therapy from 2018 to 2020 at our hospital. Two exposed groups of frozen-thawed embryo transfer (FET) were created by the endometrium preparation regimen as the modified natural cycles (mNC) and the programmed cycles. The nonexposed group was the singleton pregnancies conceived naturally. The obstetrical and perinatal outcomes were compared among the three groups using multivariate analysis to adjust the results for determinants potentially associated with the abnormal placental development.

Results

A total of 2186 pregnant women with singleton live births were included in our final analysis and were divided into three groups as naturally conceived group (n=1334), mNC-FETs group (n=217) and programmed-FETs group(n=635). After adjusting for maternal age and parity, no significant difference was observed on the risk of placental disorders between mNC-FET cycles and natural conceived pregnancies (aOR 1.16; 95%CI 1.31-7.01), while programmed-FET cycles were associated with a higher occurrence of placental disorders (aOR 5.36; 95%CI 3.63-8.05). Using the mNC-FET group as a reference and adjusting for confounders such as maternal age, parity, endometrial thickness, and number of embryos transferred, we found that the main manifestation of abnormal placentation in programmed FET cycles was abnormal placental attachment, including placental adhesion and placenta increta (aOR 2.50, 95%CI 1.36-4.90). The dysfunction of placentation in programmed-FET cycles was independently associated with the type of infertility, the total dose of Femostone and thinner endometrium. Additionally, placental disorders in the programmed-FET group were associated with higher rate of preeclampsia, postpartum hemorrhage and Cesarean section.

Conclusion

Our retrospective study revealed that the programmed-FET has a substantial impact on placental development, resulting in a higher incidence of preeclampsia, postpartum hemorrhage and Cesarean section. These findings have significant implications on clinical decision-making.

Postpartum hemorrhage among twin pregnancies - Medically assisted versus spontaneously conceived

INTRODUCTION

In singleton pregnancies, an increased risk of Postpartum hemorrhage (PPH) have been linked with assisted reproductive technology (ART) and abnormal placentation. It is unknown wheather such association exists in twin pregnancies conceived by Medically assisted reproduction (MAR). The aim of the current study was to compare maternal blood loss among twin pregnancies conceived by different types of MAR treatments to spontaneously conceived twins and to identify the cycle characteristics if an association exits.

METHODS

Retrospective study conducted on data collected between 2011 and 2020. The study cohort included all twin pregnancies conceived by MAR and born at our institution. Controls were spontaneously conceived twins matched for maternal age on a 1:2 (study: controls) ratio.

RESULTS

Overall 113 MAR twin births categorized into three groups; 25 ovulation induction, 59 fresh ART, 29 frozen-thawed ART cycles, and 226 controls were included. The incidence of PPH was higher among MAR twin pregnancies (5.3%) compared to the controls (4%). The highest incidence was observed among women in the frozen-thawed group (13.8%) which differed significantly compared with the controls (p = 0.024). A significant difference was also observed in the mean decrease of postpartum hemoglobin levels between these two groups (2.13 g/dL versus 1.3 g/dL respectively, p = 0.002). Blood transfusion was nearly 2.5 times more common in the frozen-thawed group (3.4%) compared to the control group (1.3%).

DISCUSSION

The present study demonstrates that frozen embryo transfer (FET) ART-conceived twin pregnancies are associated with a markedly increased rate of PPH compared to spontaneously conceived twins.

Pathology of the Placenta in Singletons after Assisted Reproductive Technology Compared to Singletons after Spontaneous Conception: A Systematic Review

Background: We reviewed the literature comparing the pathological characteristics of singleton births conceived after assisted reproductive technology (ART) with those after spontaneous conception. Methods: We reviewed PubMed, EMBASE, Ovid MEDLINE, Google Scopus, Scholar, Cochrane Central Register of Controlled Trials and the Web of Science for the previous 10 years, up to November 2022. Results: Four eligible studies included 3445 placentas, 806 after ART (IVF/ICSI). Placentas after ART differed in frequency of retroplacental and marginal hematomas (p = 0.04), increased thickness (p = 0.02), higher overall occurrences of vascular and anatomical pathology (p < 0.001) and more frequent marginal (p = 0.001) and membranous (p = 0.02) umbilical cord insertion than placentas from non-ART pregnancies. Conclusion: Further research is needed to determine the extent to which these placental changes in ART pregnancies alter its function and pregnancy outcome.

Thick Placenta in Pregnancy: A Review

Importance

A thickened placenta is easily identified on ultrasound and provides insight into maternal and fetal wellbeing as well as underlying structural and physiologic anomalies.

Objectives

The aim of this study was to review the literature to clarify what classifies a placenta as "thickened" and to review the associated incidence, maternal and fetal comorbidities, and management during pregnancy.

Evidence Acquisition

Electronic databases (PubMed and Web of Science) were searched from 2000 to 2020 in the English language. Studies were selected that examined associations between placental thickness, potential etiologies, and obstetric outcomes.

Results

There were 140 abstracts identified. After reviewing the articles, 60 were used in this review. Routine assessment of the placenta in the prenatal period is an easy and inexpensive way to assess the maternal and fetal patients. The criteria for a "thickened placenta" vary between studies based on gestational age, placental location, measurement technique, and maternal or fetal factors. Whereas most suggest thickness exceeding 4 cm is pathologic, a review had a threshold of 6 cm in the third trimester to classify placentomegaly. Several maternal and fetal conditions have been associated with a thickened placenta, such as obesity, parity, anemia, diabetes, preeclampsia, cardiac dysfunction, infection, assisted reproductive technology, multiple pregnancy, sacrococcygeal teratomas, and Beckwith-Wiedemann syndrome. A thickened placenta in pregnancy is associated with a higher incidence of adverse pregnancy outcomes and neonatal morbidity and mortality.

Conclusions

The literature is clear that early evaluation of the placenta using ultrasound should be a standard practice. A thickened placenta found on routine imaging should prompt a more thorough investigation to determine the etiology of the placentomegaly. At the time of this literature review, there are no recommendations regarding modality or frequency of antenatal surveillance in pregnancies complicated by a thickened placenta. However, serial ultrasounds and weekly antenatal testing in the third trimester should be considered.

Relevance

A thickened placenta has been associated with a variety of maternal and fetal conditions and increases the risk of adverse pregnancy outcomes and neonatal morbidity and mortality.

The Effect of Elevated Alanine Transaminase on Non-invasive Prenatal Screening Failures

Objective

To determine the effects of alanine transaminase (ALT) levels on the screening failure rates or “no calls” due to low fetal fraction (FF) to obtain a result in non-invasive prenatal screening (NIPS).

Methods

NIPS by sequencing and liver enzyme measurements were performed in 7,910 pregnancies at 12–26 weeks of gestation. Univariate and multivariable regression models were used to evaluate the significant predictors of screening failure rates among maternal characteristics and relevant laboratory parameters.

Results

Of the 7,910 pregnancies that met the inclusion criteria, 134 (1.69%) had “no calls.” Multiple logistic regression analysis demonstrated that increased body mass index, ALT, prealbumin, albumin levels, and in vitro fertilization (IVF) conception rates were independently associated with screening failures. The test failure rate was higher (4.34 vs. 1.41%; P &lt; 0.001) in IVF pregnancies relative to those with spontaneous conceptions. Meanwhile, the screening failure rates increased with increasing ALT levels from 1.05% at ≤10 U/L to 3.73% at &gt;40 U/L. In particular, IVF pregnancies with an ALT level of &gt;40 U/L had a higher test failure rate (9.52%). Compared with that for an ALT level of ≤10 U/L, the adjusted odds ratio of “no calls” for ALT levels of 10–20, 21–40, and &gt;40 U/L was 1.204 [95% confidence interval (CI), 0.709–2.045], 1.529 (95% CI, 0.865–2.702), and 2.764 (95% CI, 1.500–5.093) (Ptrend &lt; 0.001), respectively.

Conclusions

Increased ALT and IVF conceptions were associated with a higher screening failure rates in NIPS. Therefore, a feasible strategy to adjust these factors to reduce the probability of “no calls” due to low FF would be of great clinical significance.

Placental Dysfunction in Assisted Reproductive Pregnancies: Perinatal, Neonatal and Adult Life Outcomes

Obstetric and newborn outcomes of assisted reproductive technology (ART) pregnancies are associated with significative prevalence of maternal and neonatal adverse health conditions, such as cardiovascular and metabolic diseases. These data are interpreted as anomalies in placentation involving a dysregulation of several molecular factors and pathways. It is not clear which extent of the observed placental alterations are the result of ART and which originate from infertility itself. These two aspects probably act synergically for the final obstetric risk. Data show that mechanisms of inappropriate trophoblast invasion and consequent altered vascular remodeling sustain several clinical conditions, leading to obstetric and perinatal risks often found in ART pregnancies, such as preeclampsia, fetal growth restriction and placenta previa or accreta. The roles of factors such as VEGF, GATA3, PIGF, sFLT-1, sEndoglin, EGFL7, melatonin and of ART conditions, such as short or long embryo cultures, trophectoderm biopsy, embryo cryopreservation, and supraphysiologic endometrium preparation, are discussed. Inflammatory local conditions and epigenetic influence on embryos of ART procedures are important research topics since they may have important consequences on obstetric risk. Prevention and treatment of these conditions represent new frontiers for clinicians and biologists involved in ART, and synergic actions with researchers at molecular levels are advocated.

Gestational diabetes mellitus in in-vitro fertilization pregnancies - Clinical and placental histological characteristics

INTRODUCTION

We aimed to investigate obstetric and neonatal outcomes and placental histological findings in in vitro fertilization (IVF) pregnancies complicated by gestational diabetes mellitus (GDM) as compared to unassisted pregnancies.

METHODS

This was a retrospective cohort of deliveries at a single university affiliated center between 12/2008 and 01/2020. Included were singleton pregnancies complicated by GDM, for which placental histopathological examination was performed. Obstetric, neonatal and placental outcomes were compared between pregnancies following IVF and unassisted pregnancies. Placental lesions were categorized according to the "Amsterdam" criteria.

RESULTS

Included were 688 deliveries with a diagnosis of GDM with placental examination - 69 IVF pregnancies (IVF group) and 619 unassisted pregnancies (control group). The IVF group was characterized by a significantly higher maternal age and higher rate of nulliparous women - 60.8% vs. 32.9%, p < 0.001. There were no differences in GDM type between the study groups - about two thirds of cases were GDMA1 and on third GDMA2. A higher incidence of preeclampsia was noted in the IVF group - 17.3% vs. 9.3%, p = 0.03, with no difference in cesarean deliveries and birthweight. IVF deliveries were characterized by a significantly higher rate of adverse neonatal outcomes - 18.8% vs. 8.8%, p = 0.008, although this did not attain significance after adjustment to gestational age. No differences were noted in placental histology between the groups.

DISCUSSION

GDM in IVF is associated with a significantly higher rate of adverse neonatal outcomes, as compared with non-assisted pregnancies complicated by GDM. Placental histology does not shed light on these clinical associations.

In vitro fertilization causes excessive glycogen accumulation in mouse placenta

INTRODUCTION

Children conceived by assisted reproductive technologies have a high risk of suffering from obstetrical complications and long-term health problems, but the related mechanisms are not fully understood. Normal placental function is closely linked with foetal growth and future health. Given the significance of glycogen metabolism in placentas, we investigated the effect of in vitro fertilization (IVF) on glycogen storage in placentas using a mouse model.

METHODS

Mouse placentas were collected at E18.5 after natural mating or IVF, and the placental and foetal weights were recorded. The quantitative assay kit and histological staining were used to measure the glycogen content. Additionally, we detected the expression of multiple genes associated with glycogen synthesis/decomposition, glucose transporters, and the phosphorylation of Akt and Gsk3β.

RESULTS

Our findings showed that IVF resulted in a significantly increased mouse placental weight and enlarged junctional area. We found, compared to the control, excessive glycogen was accumulated in IVF placentas. However, we observed that multiple genes involved in glycogen generation (Gsk3b, Phka1, Phkb, Phkg1, and Phkg2) and glycogenolysis (Agl and Pygm) had lower mRNA levels in IVF placentas. Moreover, the expression levels of glycogen synthase, phosphorylase, Glut1, and Glut3 were significantly decreased in IVF placentas. The phosphorylation activities of Akt Ser473 and Gsk3β Ser9 were inhibited in IVF placentas.

DISCUSSION

IVF leads to enlarged mouse placentas with excessive glycogen storage in late pregnancy, and these abnormal changes may be associated with the activation of the Akt-Gsk3β pathway.

Effects of vitrification and the superovulated environment on placental function and fetal growth in an IVF mouse model

In studies of human IVF, as compared to frozen embryo transfer (ET), fresh ET is associated with smaller infants and higher risk of small for gestational age infants. Recent observations suggest that ET using vitrified embryos is associated with higher pregnancy and live birth rates compared to fresh ET, but increased rates of large for gestational age infants. The mechanisms underlying these associations are largely unknown, and available evidence suggests that the influence of IVF, vitrification and the superovulated (SO) uterine environment on placental function and fetal growth is complex. This warrants further investigation given the prevalent practice in human IVF of both fresh ET into a SO uterine environment, and vitrification with ET into a more physiologic uterine environment. Using a mouse model that closely resembles human IVF, we investigated if vitrification of IVF embryos better preserves placental function and results in better pregnancy outcomes as compared to fresh ET because of transfer into a more physiologic endometrium. We found that the SO environment, independent of vitrification status, reduced implantation rates, inhibited placental mechanistic target of rapamycin signaling and induced placental stress signaling, resulting in fetal growth restriction (1.080 ± 0.05 g estrous fresh (n = 17 litters), 1.176 ± 0.05 g estrous vitrified (n = 12), 0.771 ± 0.06 g SO fresh (n = 15), 0.895 ± 0.08 g SO vitrified (n = 10), P < 0.0001). In addition, our study suggests that vitrification impairs the developmental potential of IVF blastocysts that resulted in a significantly smaller litter size (2.6 ± 2.3 fresh estrous vs 2.5 ± 2.4 fresh SO vs 1.6 ± 1.7 estrous vitrified vs 1.7 ± 1.8 SO vitrified, P = 0.019), with no effect on fetal growth or placental function at term. Our findings suggest that vitrification may negatively impact early embryonic viability, while the SO maternal uterine environment impairs both placental development and fetal growth in IVF.

Altered Umbilical Cord Blood Nutrient Levels, Placental Cell Turnover and Transporter Expression in Human Term Pregnancies Conceived by Intracytoplasmic Sperm Injection (ICSI)

Assisted reproductive technologies (ART) may increase risk for abnormal placental development, preterm delivery and low birthweight. We investigated placental morphology, transporter expression and paired maternal/umbilical fasting blood nutrient levels in human term pregnancies conceived naturally (n = 10) or by intracytoplasmic sperm injection (ICSI; n = 11). Maternal and umbilical vein blood from singleton term (>37 weeks) C-section pregnancies were assessed for levels of free amino acids, glucose, free fatty acids (FFA), cholesterol, high density lipoprotein (HDL), low density lipoprotein (LDL), very low-density lipoprotein (VLDL) and triglycerides. We quantified placental expression of GLUT1 (glucose), SNAT2 (amino acids), P-glycoprotein (P-gp) and breast cancer resistance protein (BCRP) (drug) transporters, and placental morphology and pathology. Following ICSI, placental SNAT2 protein expression was downregulated and umbilical cord blood levels of citrulline were increased, while FFA levels were decreased at term (p < 0.05). Placental proliferation and apoptotic rates were increased in ICSI placentae (p < 0.05). No changes in maternal blood nutrient levels, placental GLUT1, P-gp and BCRP expression, or placental histopathology were observed. In term pregnancies, ICSI impairs placental SNAT2 transporter expression and cell turnover, and alters umbilical vein levels of specific nutrients without changing placental morphology. These may represent mechanisms through which ICSI impacts pregnancy outcomes and programs disease risk trajectories in offspring across the life course.

Placental diseases associated with assisted reproductive technology

The placenta develops from the outer trophoblastic layer following the differentiation of the fertilized ovum and is therefore more susceptible to epigenetic regulatory changes caused by environmental interventions and influences during assisted reproductive technology. Furthermore, the placenta regulates the development of the fetal heart, brain, kidneys, bones, and other tissues and organs [1]. Placental dysplasia leads to poor perinatal outcomes as well as long-term health risks later in life, including neurodevelopmental disorders, tumors, and adult metabolic syndrome [2,3]. In view of the decisive role of the placenta during intrauterine fetal development, Graham J. Burton, an expert in placentology from the University of Cambridge, formally proposed the theory of "placenta-derived chronic diseases" in 2018 based on embryonic-derived diseases [4]. In this review, we summarized the changes in placental morphology and structure, growth dynamics, imprinted and non-imprinted genes, and other aspects attributable to assisted reproduction technology. Our review provides a theoretical basis for further research on placental changes caused by assisted reproductive technology that are most strongly associated with an increased risk of neonatal long-term diseases.

Complications of the third stage of labor in in vitro fertilization pregnancies: an additional expression of abnormal placentation?

OBJECTIVE

To assess the correlation between in vitro fertilization (IVF) and complications of the third stage of labor.

DESIGN

Retrospective cohort of vaginal deliveries from November 2008 to January 2020. Maternal and obstetric outcomes of singleton deliveries were compared between IVF and non-IVF pregnancies.

SETTING

University hospital.

PATIENT(S)

Women with live singleton vaginal deliveries at >24 weeks of gestation.

INTERVENTION(S)

In vitro fertilization-attained pregnancies (compared with spontaneous ones).

MAIN OUTCOME MEASURE(S)

Complications of the third stage of labor, defined as manual placental removal (either entire removal due to nonseparation or exploration of the uterine cavity due to suspected retained products of conception).

RESULT(S)

Overall, 1,264 IVF pregnancies and 34,166 non-IVF pregnancies were included. Deliveries in the IVF group were characterized by an older maternal age, lower parity, higher rate of diabetes and hypertensive disorders, higher rate of placental abnormalities, earlier gestational age, higher rate of labor induction, chorioamnionitis, and instrumental delivery. Complications of the third stage of labor occurred in 5.9% of IVF deliveries and in 2.8% of controls, and blood transfusion was more prevalent in IVF deliveries. The rate of complications of the third stage were higher in both fresh and frozen transfer cycles as compared with spontaneous pregnancies (5.8%, 8.8%, and 2.8%, respectively), although no difference was noted between fresh and frozen transfers. In vitro fertilization was associated independently with complications of the third stage of labor after adjustment for potential confounders.

CONCLUSION(S)

In vitro fertilization is associated independently with an increased risk of complications of the third stage of labor.

Assisted reproductive technologies induce temporally specific placental defects and the preeclampsia risk marker sFLT1 in mouse

Although widely used, assisted reproductive technologies (ARTs) are associated with adverse perinatal outcomes. To elucidate their underlying causes, we have conducted a longitudinal analysis of placental development and fetal growth using a mouse model to investigate the effects of individual ART procedures: hormone stimulation, in vitro fertilization (IVF), embryo culture and embryo transfer. We demonstrate that transfer of blastocysts naturally conceived without hormone stimulation and developed in vivo prior to transfer can impair early placentation and fetal growth, but this effect normalizes by term. In contrast, embryos cultured in vitro before transfer do not exhibit this compensation but rather display placental overgrowth, reduced fetal weight, reduced placental DNA methylation and increased levels of sFLT1, an anti-angiogenic protein implicated in causing the maternal symptoms of preeclampsia in humans. Increases in sFLT1 observed in this study suggest that IVF procedures could increase the risk for preeclampsia. Moreover, our results indicate that embryo culture is the major factor contributing to most placental abnormalities and should therefore be targeted for optimization.

Placental-related disorders of pregnancy and IVF: does placental histological examination explain the excess risk?

RESEARCH QUESTION

What are the clinical characteristics of pregnancies complicated by fetal growth restriction (FGR) and preeclampsia in patients who have undergone IVF, and what is the correlation between these complications and histopathological placental findings in such pregnancies.

DESIGN

A retrospective cohort of patients who had delivered their babies at our institution who had been diagnosed with preeclampsia, whose babies had been diagnosed with FGR, or both. Deliveries in which the placenta was sent for histopathological examination were included. Computerized files and pathological reports were reviewed, and maternal, obstetric, neonatal outcomes and placental histopathological reports were compared between pregnancies conceived by IVF and controls. Placental lesions were classified according to the Amsterdam criteria.

RESULTS

Between December 2008 and December 2018, the placentas of 1114 singleton babies who had received a diagnosis of FGR, whose mothers had received a diagnosis of preeclampisa, or both, were examined. A total of 105 patients conceived with IVF and 1009 were conceived spontaneously. The IVF group was older, of lower parity and had a higher rate of diabetes and chronic hypertension. Deliveries occurred at an earlier gestational age, although birth weight was not significantly different between the groups. The rate of neonatal adverse composite outcome among IVF deliveries was significantly lower (59.0% versus 76.7%; P < 0.001). On placental examination, placental weight, maternal and fetal vascular malperfusion lesions were similar between the groups, whereas villitis of unknown etiology was significantly more common among the IVF group (16.2% versus 8.3%; P = 0.007).

CONCLUSION

Neonatal outcome is relatively favourable in IVF patients with placental-related diseases. Placental chronic villitis is more common in IVF patients, pointing to an additive immunological cause.

Risk of prematurity and infant morbidity and mortality by maternal fertility status and plurality

PURPOSE

To evaluate the risk of prematurity and infant mortality by maternal fertility status, and for in vitro fertilization (IVF) pregnancies, by oocyte source and embryo state combinations.

METHODS

Women in 14 States who had IVF-conceived live births during 2004-13 were linked to their infant's birth and death certificates; a 10:1 sample of non-IVF births was selected for comparison; those with an indication of infertility treatment on the birth certificate were categorized as subfertile, all others were categorized as fertile. Risks were modeled separately for the fertile/subfertile/IVF (autologous-fresh only) group and for the IVF group by oocyte source-embryo state combinations, using logistic regression, and reported as adjusted odds ratios (AORs) and 95% confidence intervals (CI).

RESULTS

The study population included 2,474,195 pregnancies. Placental complications (placenta previa, abruptio placenta, and other excessive bleeding) and prematurity were both increased with pregestational and gestational diabetes and hypertension, among subfertile and IVF groups, and in IVF pregnancies using donor oocytes. Both subfertile and IVF pregnancies were at risk for prematurity and NICU admission; IVF infants were also at risk for small-for-gestation birthweight, and subfertile infants had greater risks for neonatal and infant death. Within the IVF group, pregnancies with donor oocytes and/or thawed embryos were at greater risk of large-for-gestation birthweight, and pregnancies with thawed embryos were at greater risk of neonatal and infant death.

CONCLUSIONS

Prematurity was associated with placental complications, diabetes and hypertension, subfertility and IVF groups, and in IVF pregnancies, donor oocytes and/or thawed embryos.

Abnormal placentation: Current evidence and review of the literature

Abnormal placentation often requires the involvement of a multidisciplinary team of medical caregivers. Practicing Obstetrics is a challenging and skillful duty. This is more obvious in cases of abnormal placentation, which represents one of the most dangerous and complex clinical conditions in materno-fetal medicine. Pathological placentation involves position and invasion abnormalities and represents a serious and potentially life-threatening condition for both the pregnant woman and the fetus. The dramatic increase in cesarean section rates is an important factor which could explain the rapid raise in abnormal placentation cases, which were considered rare a few years ago. Nevertheless, the scientific armamentarium sometimes seems to be poor and this could be explained by the fact that treatment options are offered too late, since this condition is often detected late, entailing higher patients' risks. In fact, the later the diagnosis is made the poorer the prognosis is for cases of abnormal placentation. Given that abnormal placentation is constantly increasing, the scientific community should aim at early diagnosis and appropriate management of such cases based on the best evidence available. Future improvement of knowledge and practice lies in perspective, preferably randomized studies so that we obtain high quality of evidence which is still needed. The purpose of this study is to review the current literature and to update the available scientific knowledge on the topic of abnormal placentation which is an emerging issue which clinicians should learn to deal with, considering its continuous increase in the last years.

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

BACKGROUND

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

OBJECTIVE

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

STUDY DESIGN

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

RESULTS

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

CONCLUSION

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

Abnormal Placentation Associated with Infertility as a Marker of Overall Health

Infertility and fertility treatments utilized are associated with abnormal placentation leading to adverse pregnancy outcomes related to placentation, including preterm birth, low birth weight, placenta accrete, and placenta previa. This may be due to the underlying genetics predisposing to infertility or the epigenetic changes associated with the fertility treatments utilized, as specific disease states leading to infertility are at increased risk of adverse outcomes, including placental abruption, fetal loss, gestational diabetes mellitus, and outcomes related to placentation, as well as the treatments utilized including in vitro fertilization (IVF) and non-IVF fertility treatment. Placentation defects, leading to adverse maternal and fetal outcomes, which are more pronounced in the infertile population, occur due to changes in trophoblast invasion, vascular defects, changes in the environmental milieu, chronic inflammation, and oxidative stress. These similar processes are recognized as major contributors to lifelong risk of cardiovascular and metabolic disease for both the mother and her offspring. Thus, abnormal placentation, found to be more prevalent in the infertile population, may be the key to better understand how infertility affects overall and long-term health.

The health outcomes of human offspring conceived by assisted reproductive technologies (ART)

Concerns have been raised about the health and development of children conceived by assisted reproductive technologies (ART) since 1978. Controversially, ART has been linked with adverse obstetric and perinatal outcomes, an increased risk of birth defects, cancers, and growth and development disorders. Emerging evidence suggests that ART treatment may also predispose individuals to an increased risk of chronic ageing related diseases such as obesity, type 2 diabetes and cardiovascular disease. This review will summarize the available evidence on the short-term and long-term health outcomes of ART singletons, as multiple pregnancies after multiple embryos transfer, are associated with low birth weight and preterm delivery, which can separately increase risk of adverse postnatal outcomes, and impact long-term health. We will also examine the potential factors that may contribute to these health risks, and discuss underlying mechanisms, including epigenetic changes that may occur during the preimplantation period and reprogram development in utero, and adult health, later in life. Lastly, this review will consider the future directions with the view to optimize the long-term health of ART children.

Morphologic and molecular changes in the placenta: what we can learn from environmental exposures

In mammals, the extraembryonic tissues, which include the placenta, are crucial for embryonic development and growth. Because the placenta is no longer needed for postnatal life, however, it has been relatively understudied as a tissue of interest in biomedical research. Recently, increased efforts have been placed on understanding the placenta and how it may play a key role in human health and disease. In this review, we discuss two very different types of environmental exposures: assisted reproductive technologies and in utero exposure to endocrine-disrupting chemicals. We summarize the current literature on their effects on placental development in both rodent and human, and comment on the potential use of placental biomarkers as predictors of offspring health outcomes.

Biochemical markers of placental dysfunction in assisted conception

A possible mechanism for poor perinatal outcomes in singleton pregnancies conceived following assisted reproductive technologies (ART) and those conceived naturally following a period of infertility (>12 months) is thought to be placental dysfunction. This was investigated by measuring plasma concentrations of biochemical markers: (i) soluble fms-like tyrosine kinase1 (sFlt1); (ii) placental growth factor (PlGF); (iii) leptin; and (iv) plasminogen activator inhibitor 2 (PAI-2), serially at four antenatal time points. Baseline concentrations of each marker after delivery were also measured. The control group was naturally conceived singleton pregnancies with no history of infertility. Non-smoking, age-matched nulliparous women with no significant medical history were recruited to all groups. The ART group had significantly lower mean plasma concentrations of PlGF at all antenatal time points compared to the control group (p < 0.001). The subfertility (SF) group had significantly higher mean serum concentrations of leptin than the other groups at all time points (p < 0.001), even after correction for body mass index. There were no significant differences in sFlt1 and PAI-2 concentrations between the groups. Low plasma PlGF concentrations in the ART group might suggest abnormal placentation and/or abnormal function in ART pregnancies with relevance to pathogenesis of pregnancy complications in these women.

Comparative intrauterine development and placental function of ART concepti: implications for human reproductive medicine and animal breeding

BACKGROUND

The number of children conceived using assisted reproductive technologies (ART) has reached >5 million worldwide and continues to increase. Although the great majority of ART children are healthy, many reports suggest a forthcoming risk of metabolic complications, which is further supported by the Developmental Origins of Health and Disease hypothesis of suboptimal embryo/fetal conditions predisposing adult cardiometabolic pathologies. Accumulating evidence suggests that fetal and placental growth kinetics are important features predicting post-natal health, but the relationship between ART and intrauterine growth has not been systematically reviewed.

METHODS

Relevant studies describing fetoplacental intrauterine phenotypes of concepti generated by in vitro fertilization (IVF), intracytoplasmic sperm injection (ICSI) and somatic cell nuclear transfer (SCNT) in the mouse, bovine and human were comprehensively researched using PubMed and Google Scholar. Intrauterine growth plots were created from tabular formatted data available in selected reports.

RESULTS

ART pregnancies display minor but noticeable alterations in fetal and placental growth curves across mammalian species. In all species, there is evidence of fetal growth restriction in the earlier stages of pregnancy, followed by significant increases in placental size and accelerated fetal growth toward the end of gestation. However, there is a species-specific effect of ART on birthweights, that additionally vary in a culture condition-, strain-, and/or stage at transfer-specific manner. We discuss the potential mechanisms that underlie these changes, and how they are affected by specific components of ART procedures.

CONCLUSIONS

ART may promote measurable alterations to intrauterine growth trajectory and placental function. Key findings include evidence that birthweight is not a reliable marker of fetal stress, and that increases in embryo manipulation result in more deviant fetal growth curves. Because growth kinetics in early life are particularly relevant to adult metabolic physiology, we advise more rigorous assessment of fetal growth and placental function in human ART pregnancies, as well as continued follow-up of ART offspring throughout post-natal life. Finally, strategies to minimize embryo manipulations should be adopted whenever possible.

First trimester trophoblast and placental bed vascular volume measurements in IVF or IVF/ICSI pregnancies

STUDY QUESTION

Are first trimester trophoblast volume (TV) and placental bed vascular volume (PBVV) different in IVF or IVF/ICSI pregnancies in comparison with spontaneously conceived pregnancies?

SUMMARY ANSWER

Any possible abnormal placentation in IVF or IVF/ICSI pregnancies in comparison with spontaneously conceived pregnancies is not detected by a difference in PBVV or TV at an early gestational age (GA).

WHAT IS KNOWN ALREADY

Assisted reproductive technology pregnancies have been associated with an increased risk of placenta-related adverse pregnancy outcomes. It is unclear whether these effects originate from infertility or from the technique itself.

STUDY DESIGN, SIZE, DURATION

We performed a retrospective cohort study in which 154 pregnant patients qualified for participation.

PARTICIPANTS/MATERIALS, SETTING, METHODS

Out of 154 pregnant patients, 84 conceived spontaneously and 70 conceived after IVF or IVF/ICSI. We determined the TV at 10 weeks GA by Virtual Organ Computer-aided AnaLysis measuring application and the PBVV at 12 weeks GA by the virtual reality operating system of BARCO I-Space in both subgroups. The investigators were blinded to the mode of conception during the measurements. Analysis was limited to singleton pregnancies with only one sac ever detectable.

MAIN RESULTS AND THE ROLE OF CHANCE

There were no differences in TV (mean 42.7, SD 15.9 versus mean 41.2, SD 13.9, P = 0.70) and PBVV (mean 27.6, SD 16.9 versus mean 24.8, SD 19.9, P = 0.20) between IVF or IVF/ICSI pregnancies and spontaneously conceived pregnancies. There was a significant correlation between TV and PBVV (rs = 0.283, P = 0.004).

LIMITATIONS, REASONS FOR CAUTION

The limitations of the present study concern the small size of the study groups.

WIDER IMPLICATIONS OF THE FINDINGS

IVF or IVF/ICSI does not seem to be associated with abnormal placentation.

STUDY FUNDING/COMPETING INTERESTS

This study was financially supported by the Erasmus Trustfonds, the Meindert de Hoop foundation and the Fonds NutsOhra. No competing interests are declared.