Low and very low birth weight in infants conceived with use of assisted reproductive technology

Can we generalise from findings in twins?

A number of recent studies have used data from twins to shed light on the causal pathways underlying the observed association between birthweight and cardiovascular risk factors or coronary heart disease. The issue of whether findings from twin studies are generally informative, or whether factors associated with twinning preclude generalisation, is considered here. It is concluded that the association between birthweight and later health may differ quantitatively between twins and singletons, but evidence regarding blood pressure suggests it may not differ qualitatively. However, more information is needed on a number of gestational and maternal factors, and on measures of health other than blood pressure. Placentation and issues relating to infertility and its treatment need to be recorded and, together with gestation length, may need to be taken into account in analyses.

Effect of inner myometrium fibroid on reproductive outcome after IVF

To evaluate the influence of inner myometrium fibroids (myomas) on the outcome of IVF cycles, a retrospective agematched controlled study was performed at SISMeR Reproductive Medicine Unit. The study group included 129 IVF/intracytoplasmic sperm injection cycles in 75 patients with one or more intramural and/or submucosal fibroids, while the control group consisted of 129 cycles in 127 patients without fibroids. The two groups were similar for mean oestradiol concentration at human chorionic gonadotrophin administration (1205.16 +/- 874 versus 1395 +/- 821 pg/ml), mean number of transferred embryos (2.02 +/- 0.4 versus 2.14 +/- 0.6) and clinical pregnancy rate (34.9 versus 41.1%). Conversely, the implantation rate was significantly lower in the study group (18.0%) than in the control group (26.5%; chi(2) = 4.81, P < 0.05), whereas the rate of spontaneous abortion demonstrated an opposite trend (40 versus 18.9%; chi(2) = 4.34, P < 0.05). Further research should be aimed at classifying fibroids on the basis of their location, especially when they are positioned in the junctional zone of the myometrium. Whether this classification will be superior in predicting the impact of fibroids on the reproductive outcome should be elaborated in a large multicentric study.

Research hurdles complicating the analysis of infertility treatment and child health

Research aimed at the empirical evaluation of infertility treatment including assisted reproductive technologies (ART) on child health and development is hampered by investigators' inability to methodologically separate possible treatment effects from underlying fecundity impairments. While the literature continues to identify ART as a risk factor for many child health outcomes, less attention has been paid to the methodologic rigor needed to answer this question. We identify aspects of fecundity and the nuances of medical practice that need to be considered and captured when designing epidemiologic investigations aimed at assessing ART and child health. These include: (i) the use of prospective study designs in which the unit of analysis (cycle versus individual versus couple) is defined; (ii) data collection on relevant time-varying covariates at, before and during treatment; and (iii) the use of statistical techniques appropriate for hierarchical data and correlated exposures. While none of these issues in and by itself is unique to ART research, attention to these issues has been lacking in much of the published research limiting our ability to evaluate health consequences for children. Longitudinal studies of children conceived with ART will benefit from attention to these issues and, hopefully, produce answers to lingering questions about safety.

Perinatal outcome of ICSI pregnancies compared with a matched group of natural conception pregnancies in Flanders (Belgium): a cohort study

A retrospective cohort study was conducted with an intracytoplasmic sperm injection (ICSI) group and a naturally conceived comparison group. A total of 1655 singleton and 1102 twin ICSI births were studied with regard to perinatal outcome. Control subjects (naturally conceived pregnancies) were selected from a regional registry and were matched for maternal age, parity, place of delivery, year of birth and fetal sex. The main outcome measures were duration of pregnancy, birth weight, Apgar score <5 after 5 min, neonatal complications, perinatal death and congenital malformations. Twin births, when compared with singletons, carry a much higher risk of poor perinatal outcome. For both ICSI singletons and ICSI twins, no significant difference was found between ICSI and naturally conceived pregnancies for all investigated parameters. After excluding like-sex twin pairs, ICSI twin pregnancies were at increased risk for perinatal mortality (OR = 2.74, CI = 1.26-5.98), prematurity (OR = 1.38, CI = 1.10-1.75) and low birth weight (OR = 1.34, CI = 1.06-1.69) compared with spontaneously conceived different-sex twin pairs. In conclusion, the perinatal outcome of ICSI singleton and twin pregnancies was very similar to that of spontaneously conceived pregnancies in this large cohort study. After excluding like-sex twin pairs, ICSI twins were at increased risk for prematurity, low birth weight and higher perinatal mortality compared with the natural conception comparison group.

Elective single-embryo transfer versus double-embryo transfer in in vitro fertilization

BACKGROUND

The risks of premature birth and perinatal death are increased after in vitro fertilization. These risks are mainly due to the high incidence of multiple births, which relates to the number of embryos transferred.

METHODS

We performed a randomized, multicenter trial to assess the equivalence of two approaches to in vitro fertilization with respect to the rates of pregnancy that result in at least one live birth and to compare associated rates of multiple gestation. Women less than 36 years of age who had at least two good-quality embryos were randomly assigned either to undergo transfer of a single fresh embryo and, if there was no live birth, subsequent transfer of a single frozen-and-thawed embryo, or to undergo a single transfer of two fresh embryos. Equivalence was defined as a difference of no more than 10 percentage points in the rates of pregnancy resulting in at least one live birth.

RESULTS

Pregnancy resulting in at least one live birth occurred in 142 of 331 women (42.9 percent) in the double-embryo-transfer group as compared with 128 of 330 women (38.8 percent) in the single-embryo-transfer group (difference, 4.1 percentage points; 95 percent confidence interval, -3.4 to 11.6 percentage points); rates of multiple births were 33.1 percent and 0.8 percent, respectively (P<0.001). These results do not demonstrate equivalence of the two approaches in rates of live births, but they do indicate that any reduction in the rate of live births with the transfer of single embryos is unlikely to exceed 11.6 percentage points.

CONCLUSIONS

In women under 36 years of age, transferring one fresh embryo and then, if needed, one frozen-and-thawed embryo dramatically reduces the rate of multiple births while achieving a rate of live births that is not substantially lower than the rate that is achievable with a double-embryo transfer.

Survival of triplets who are born to teen mothers in the United States

OBJECTIVE

The purposes of this study were to assess survival among triplets who are born to teen mothers and to determine whether fetal number influences the mortality rates of the offspring of teen mothers when compared with the offspring of older women.

STUDY DESIGN

A retrospective cohort study of 354 triplet births to teenage mothers and 6858 to young mature mothers (20-29 years) who were delivered from 1995 through 1998. We compared the occurrence of stillbirth and neonatal and infant mortality rates between the 2 categories by means of the generalized estimating equation. Similar analyses were conducted for singleton pregnancies and twin pregnancies.

RESULTS

Triplets of teenage mothers experienced a higher level of stillbirth (odds ratio, 3.24; 95% CI, 1.44-7.24), neonatal mortality (odds ratio, 2.00; 95% CI, 1.11-3.61), and infant death (odds ratio, 1.66; 95% CI, 1.01-2.87). Moreover, as the plurality increased from singleton infant to triplet, the offspring of teenagers fared progressively worse ( P < .0001).

CONCLUSION

This study confirms the association between teenage motherhood and feto-infant death and indicates that this mortality relationship varies in a dose-dependent fashion.

Increased risk of preterm birth in singleton pregnancies resulting from in vitro fertilization–embryo transfer or gamete intrafallopian transfer: A meta-analysis

OBJECTIVE

To perform a systematic review of the literature to determine whether singleton pregnancies resulting from IVF-ET/GIFT are at higher risk for preterm birth (<37 weeks).

DESIGN

Literature search and systematic review.

SETTING

Medical school.

INTERVENTION(S)

A MEDLINE search (1965-2000) was performed using the terms "premature labor," "infertility," "pregnancy complications," "gonadotropins," "pregnancy outcome," "preterm delivery," and "in vitro fertilization." Criteria for inclusion were English language, original research article, study patients conceived using IVF-ET (with or without intracytoplasmic sperm injection) or GIFT, pregnancy outcome reported compared with a control group (e.g., naturally conceived singletons at their hospital or a national reference), and prematurity clearly defined. Incomplete articles (e.g., abstracts), reports of other studies, and studies that failed to separate multiple from singleton gestations were excluded.

MAIN OUTCOME MEASURE(S)

Summary of relative risks of preterm birth.

RESULT(S)

Twenty-seven articles met all inclusion/exclusion criteria and were analyzed by meta-analysis. The random-effects summary relative risk of preterm birth in singleton pregnancies resulting from IVF-ET/GIFT was 1.98 (95% confidence interval, 1.77-2.22).

CONCLUSION(S)

The risk of preterm birth in singleton pregnancies resulting from IVF-ET/GIFT is twice that of natural conceived pregnancies.

Care of very premature infants: looking to the future

Advances in prenatal care have improved survival rates in extremely preterm newborns, but cerebral palsy rates have not decreased in developed countries over the past 30 years. During the next 10 years we will probably not observe a dramatic improvement in intensive care such as that observed over the last 15 years. The man goal for the coming years will be to improve the quality of neonatal and postdischarge care in order to improve the long-term outcomes of very preterm infants.

Neonatal outcome in a Danish national cohort of 8602 children born after in vitro fertilization or intracytoplasmic sperm injection: the role of twin pregnancy

BACKGROUND

In Denmark, 4% of all infants are born after in vitro fertilization (IVF) or intracytoplasmic sperm injection (ICSI) and 40% of these children are twins.

METHODS

We investigated neonatal outcome in a complete Danish IVF/ICSI birth cohort including 8602 infants born between 1995 and 2000: 3438 twins (40%) and 5164 singletons (60%). Births conceived after IVF or ICSI were identified by record linkage with the Danish IVF Registry and the National Medical Birth Registry. Data on neonatal outcome were collected from the National Patient Registry.

RESULTS

IVF/ICSI twins had a 10-fold increased age- and parity-adjusted risk of delivery before 37 completed weeks [odds ratio (OR) 9.9, 95% confidence interval (95% CI) 8.7-11.3] and a 7.4-fold increased risk of delivery before 32 completed weeks (OR 7.4, 95% CI 5.6-9.8) compared with singletons. Correspondingly, ORs of birthweight <2500 g and birthweight <1500 g in twins were 11.8 (95% CI 10.3-13.6) and 5.4 (95% CI 4.1-7.0), respectively. The stillbirth rate was doubled in twins (13.1/1000) compared with singletons (6.6/1000) (p = 0.002). The risk of cesarean section and of admittance to a neonatal intensive care unit (NICU) was 4.6- and 1.8-fold higher in IVF/ICSI twins than in singletons. The rate of major malformations was 40.4/1000 in twins and 36.8/1000 in singletons (p = 0.4), whereas the total malformation rate (major + minor) was higher in twins (73.7/1000) than in singletons (55.0/1000) (p = 0.001). After exclusion of patent ductus arteriosus (PDA), which is strongly associated with preterm birth, no significant differences in any malformation rates were observed between twins and singletons. Apart from the frequency of ICSI children with hypospadias, which reached a significance level of p = 0.05, malformation rates in ICSI children were similar to those in IVF children.

CONCLUSIONS

This study indicates that neonatal outcome in IVF/ICSI twins is considerably poorer than in singletons. Thus, the impact is to draw the attention of clinicians to the benefit of elective single embryo transfer (eSET).

Single embryo transfer and IVF/ICSI outcome: a balanced appraisal

This review considers the value of single embryo transfer (SET) to prevent multiple pregnancies (MP) after IVF/ICSI. The incidence of MP (twins and higher order pregnancies) after IVF/ICSI is much higher (approximately 30%) than after natural conception (approximately 1%). Approximately half of all the neonates are multiples. The obstetric, neonatal and long-term consequences for the health of these children are enormous and costs incurred extremely high. Judicious SET is the only method to decrease this epidemic of iatrogenic multiple gestations. Clinical trials have shown that programmes with >50% of SET maintain high overall ongoing pregnancy rates ( approximately 30% per started cycle) while reducing the MP rate to <10%. Experience with SET remains largely European although the need to reduce MP is accepted worldwide. An important issue is how to select patients suitable for SET and embryos with a high putative implantation potential. The typical patient suitable for SET is young (aged <36 years) and in her first or second IVF/ICSI trial. Embryo selection is performed using one or a combination of embryo characteristics. Available evidence suggests that, for the overall population, day 3 and day 5 selection yield similar results but better than zygote selection results. Prospective studies correlating embryo characteristics with documented implantation potential, utilizing databases of individual embryos, are needed. The application of SET should be supported by other measures: reimbursement of IVF/ICSI (earned back by reducing costs), optimized cryopreservation to augment cumulative pregnancy rates per oocyte harvest and a standardized format for reporting results. To make SET the standard of care in the appropriate target group, there is a need for more clinical studies, for intensive counselling of patients, and for an increased sense of responsibility in patients, health care providers and health insurers.

Genomic imprinting and assisted reproduction

Imprinted genes exhibit a parent-of-origin specific pattern of expression. Such genes have been shown to be targets of molecular defects in particular genetic syndromes such as Beckwith-Wiedemann and Angelman syndromes. Recent reports have raised concern about the possibility that assisted reproduction techniques, such as in vitro fertilization or intracytoplasmic sperm injection, might cause genomic imprinting disorders. The number of reported cases of those disorders is still too small to draw firm conclusions and the safety of these widely used assisted reproduction techniques needs to be further evaluated.

Endometrial endotoxin, assisted reproductive technology, and preterm birth

The failure of antibiotic prophylaxis to reduce preterm birth in women at risk and the increased rate of preterm birth in singleton pregnancy after ART may have a common explanation: persistent bacterial endotoxin in the endometrium, reported by Kamiyama et al. as an explanation for reduced fertility.

Perinatal outcome of twin pregnancies after in vitro fertilization

BACKGROUND

There are conflicting data concerning perinatal outcome of twin, in vitro fertilization (IVF) pregnancies. The aim of this study was to evaluate and compare perinatal and neonatal outcomes in twin IVF pregnancies to those of spontaneously conceived twin gestations.

METHODS

The medical files of 73 IVF and 148 naturally conceived twin pregnancies were studied retrospectively. Data concerning maternal characteristics, obstetric complications, and neonatal outcome were recorded and compared by chi2 test. The one-way analysis of variance (anova) was used to compare the means of groups.

RESULTS

Mean maternal age, the proportion of nulliparous women, and the incidence of premature rupture of membranes, cesarean section, and premature delivery were significantly higher in the study group. The mean birthweight was significantly lower, the frequency of admission to the intensive care unit and the duration of hospitalization were significantly higher in the study group. The incidence of intraventricular hemorrhage was significantly higher in the IVF group. The number of perinatal deaths was similar.

CONCLUSION

IVF twin pregnancies are at greater risk for obstetric complications and adverse neonatal outcome in comparison with naturally conceived twin gestations.

The Embryo and Its Future1

The preimplantation mammalian embryo from different species appears sensitive to the environment in which it develops, either in vitro or in vivo, for example, in response to culture conditions or maternal diet. This sensitivity may lead to long-term alterations in the characteristics of fetal and/or postnatal growth and phenotype, which have implications for clinical health and biotechnological applications. We review the breadth of environmental influences that may affect early embryos and their responses to such conditions along epigenetic, metabolic, cellular, and physiological directions. In addition, we evaluate how embryo environmental responses may influence developmental potential and phenotype during later gestation. We conclude that a complex of different mechanisms may operate to associate early embryo environment with future health.

Do multiple gestations raise the risk of cerebral palsy?

There is an increased risk of CP in multiple as compared with singleton pregnancies, and the higher the number of fetuses the greater is the prevalence of CP. Although LBW and preterm birth are the most significant risk factors for CP, the disadvantage of twins is apparent near term. Moreover, the excessive risk is not only the result of over-representation of multiples among premature babies, but seems to be associated with circumstances that are unique to the twinning process. The risk of CP should be acknowledged not only when a multiple pregnancy is diagnosed, but also when counseling infertility patients in whom iatrogenic multiple pregnancies are an actual risk.

Measuring progress in meeting healthy people goals for low birth weight and infant mortality among the 100 largest cities and their suburbs

We examined the progress of the nation's 100 largest cities and their surrounding suburban areas toward achieving Healthy People 2000/2010 goals for two measures of infant health: low birth weight (LBW) and infant mortality (IM). Using data from the National Center for Health Statistics, we compared 1990 and 2000 urban and suburban LBW and IM rates to target rates for Healthy People 2000 and 2010 objectives. Although the 2000 LBW weight rate for the 100 largest cities was higher than the average for the suburbs (8.9% vs. 7.1%), the increase in LBW rates for the suburbs was nearly four times that of the cities (15.7% vs. 4.1%). Suburban and urban white infants led the increases in LBW rates; urban and suburban black infants showed a slight decrease or no change in LBW rates. Neither cities nor suburbs, on average, met the 2000 target rate of 5%. It appears unlikely that most of the 100 largest cities and suburbs will meet the Healthy People 2010 goal, which remains at 5%, without reductions in preterm births, nationally on the rise. The IM rate declined across most cities and suburbs between 1990 and 2000. However, the 100 largest cities on average did not meet the 2000 IM rate target of 7 infant deaths per 1000 live births; their suburbs did (8.5 vs. 6.4, respectively). The cities and suburbs that did not meet the 2000 target may be especially challenged to meet the 2010 goal for IM unless rates of preterm births are reduced. With the continuing black-white disparities in LBW and IM rates and the overall differences in the racial composition of the largest cities and suburbs, strategies for meeting Healthy People goals will likely need to be targeted to the specific populations they serve.

What's new in prenatal screening and diagnosis?

This article provides clinicians with an overview of current methods for prenatal genetic screening and diagnosis. Topics include developments in prenatal screening procedures such as ethnicity-based carrier testing, maternal serum screening, and ultrasonography. Diagnostic alternatives to amniocentesis include chorionic villus sampling and preimplantation diagnosis. Future endeavors such as three-dimensional ultrasonography and fetal cell sorting are discussed.

The impact of multiple pregnancies and malformations on perinatal mortality

AIM

To evaluate the impact of the rate of multiple pregnancies and congenital malformations on perinatal mortality.

METHODS

The study is based on data from the perinatal audit in Vejle County Denmark. Fetal deaths with gestational age > or = 22 weeks and deaths in livebirths within the first 28 days after birth were included in the calculated perinatal mortality. Total number of births was 30,181 and 252 pregnancies and 268 fetuses/infants were evaluated. The study period was 1995-2000. There was no routine ultrasound screening for congenital malformations in the county, though midtrimester ultrasound was used to assess gestational age.

RESULTS

Perinatal mortality was 8.9 per 1000 births with no significant change over time. Rate of multiple pregnancies was 1.94% ranging from 1.81% during the first 3 years to 2.06% for the last 3 years (not significant). Fetuses and infants from multiple pregnancies contributed 18% of all deaths. Perinatal mortality for single births was 7.6 per 1000 births and for multiple births 42.2/1000 (P<0.0001). The distribution of gestational age for single and multiple births was highly significant (P<0.0001) with 67% of multiple pregnancies with GA < 28 weeks compared to 26% of single pregnancies. Nineteen percent of all deaths were caused by congenital malformations and the majority of these were potentially detectable by ultrasound investigation.

CONCLUSIONS

The increasing rate of multiple pregnancies makes it difficult to see improvements in perinatal mortality. Calculated from the perinatal mortality in single and multiple pregnancies in Vejle County assisted conceptions contribute with an an excess of 45 perinatal deaths per year in Denmark. The difference between countries in rate of multiple pregnancies and in prenatal ultrasound screening recommendations for malformations makes it difficult to compare perinatal mortality.

Neurological sequelae in twins born after assisted conception: controlled national cohort study

OBJECTIVE

To compare neurological sequelae in twins born after assisted conception with singletons after assisted conception and naturally conceived twins and to assess neurological sequelae in children conceived after in vitro fertilisation (IVF) compared with intracytoplasmic sperm injection (ICSI).

DESIGN

Controlled, national register based, cohort study.

PARTICIPANTS

Twins (n = 3393) and singletons (n = 5130) conceived by using assisted reproductive technologies and naturally conceived twins (n = 10 239) born in Denmark between 1995 and 2000. The children's age at time of follow up was 2-7 years.

DATA SOURCES

Children were identified by cross linkage of the national medical birth registry and the national registry for in vitro fertilisation. Neurological and psychiatric diagnoses were retrieved from the national patients' registry and the Danish psychiatric central registry.

MAIN OUTCOME MEASURES

Neurological sequelae, defined as cerebral palsy, mental retardation, severe mental developmental disturbances, and retarded psychomotor development. Further we made separate analyses on the specific cerebral palsy diagnosis.

RESULTS

The crude prevalence rates per 1000 of neurological sequelae in twins and singletons after assisted conception and in naturally conceived twins were 8.8, 8.2, and 9.6, and of cerebral palsy 3.2, 2.5, and 4.0, respectively. In twins after assisted conception compared with control twins, the odds ratios of neurological sequelae and specifically of cerebral palsy, adjusted for child sex and year of birth, were 0.9 (95% confidence interval 0.6 to 1.4) and 0.8 (0.4 to 1.6), respectively. The corresponding odds ratios for twins after assisted conception compared with singletons after assisted conception were 1.1 (0.7 to 1.7) for neurological sequelae and 1.3 (0.6 to 2.9) for cerebral palsy. The odds ratio of neurological sequelae in children conceived by ICSI was 0.9 (0.5 to 1.7) nu children conceived by IVF.

CONCLUSIONS

Twins from assisted conception have a similar risk of neurological sequelae as their naturally conceived peers and singletons from assisted conception. Children born after ICSI have the same risk of neurological sequelae as children born after IVF.

Perinatal outcome among singleton infants conceived through assisted reproductive technology in the United States

OBJECTIVE

To examine perinatal outcome among singleton infants conceived with assisted reproductive technology (ART) in the United States.

METHODS

Subjects were 62,551 infants born after ART treatments performed in 1996-2000. Secular trends in low birth weight (LBW), very low birth weight (VLBW), preterm delivery, preterm LBW, and term LBW were examined. Detailed analyses were performed for 6,377 infants conceived in 2000. Observed numbers were compared with expected using a reference population from the 2000 U.S. natality file. Adjusted risk ratios were calculated.

RESULTS

The proportion of ART singletons born LBW, VLBW, and term LBW decreased from 1996 to 2000. The proportion delivered preterm and preterm LBW remained stable. After adjustment for maternal age, parity, and race/ethnicity, singleton infants born after ART in 2000 had elevated risks for all outcomes in comparison with the general population of U.S. singletons: LBW standardized risk ratio 1.62 (95% confidence interval 1.49, 1.75), VLBW 1.79 (1.45, 2.12), preterm delivery 1.41 (1.32, 1.51), preterm LBW 1.74 (1.57, 1.90), and term LBW 1.39 (1.19, 1.59). Risk ratios for each outcome remained elevated after restriction to pregnancies with only 1 fetal heart or any of 7 other categories: parental infertility diagnosis of male factor, infertility diagnosis of tubal factor, conception using in vitro fertilization without intracytoplasmic sperm injection or assisted hatching, conception with intracytoplasmic sperm injection, conception in a treatment with extra embryos available, embryo culture for 3 days, and embryo culture for 5 days.

CONCLUSION

Singletons born after ART remain at increased risk for adverse perinatal outcomes; however, risk for term LBW declined from 1996 to 2000, whereas preterm LBW was stable.

LEVEL OF EVIDENCE

III

Low maternal age and neonatal survival of extremely preterm twins (20-28 weeks of gestation)

OBJECTIVE

We investigated the relationship between low maternal age and neonatal survival among extremely preterm twins.

METHODS

This was a retrospective cohort study on live births of extremely preterm twins delivered to teenaged mothers (aged 15-19 years) in the United States within the period 1995 through 1998. Overall neonatal and early and late neonatal mortality in this category was compared with that of a similar group of twins born to young adult mothers (aged 20-29 years). We used the generalized estimating equation framework in computing relative risks after adjusting for intracluster correlations.

RESULTS

Analysis involved 2,290 extremely preterm liveborn twins of teenaged mothers and 8,709 born to young adult mothers. Overall, neonatal mortality was 29% higher among the extremely preterm twins born to teenaged mothers (adjusted odds ratio [OR] 1.29; 95% confidence interval [CI] 1.04%, 1.59%). The disparity in neonatal survival was chiefly in the early neonatal period (adjusted OR 1.34; 95% CI 1.07%, 1.67%), while late neonatal mortality was comparable (adjusted OR 0.91; 95% CI 0.58%, 1.42%). In addition, twins of teenaged mothers had significantly higher level of mortality, except for the birth weight category of 1,000-1,499 g.

CONCLUSION

Low maternal age was found to be associated with elevated risk of neonatal death among extremely preterm twins. The preponderance of deaths among extremely preterm twins of teenaged mothers in the early neonatal period appeared to be responsible for the disparity in survival. This information may be useful for targeted interventions aimed at enhancing survival of extremely preterm twins born to teenagers, as well as for instituting optimal management options in the clinical setting.

LEVEL OF EVIDENCE

II-2

Are children born after assisted reproductive technology at increased risk for adverse health outcomes?

As assisted reproductive technologies (ARTs) are increasingly used to overcome infertility, there is concern about the health of the children conceived. The empirical evidence for associations with outcomes related to child health is variable and should be evaluated with consideration of methodological shortcomings. Currently, there is convincing evidence that ART treatment may increase the risk of a few outcomes. Experimental laboratory studies document that various constituents in culture media affect various embryo characteristics both positively and negatively. Multiple-gestation pregnancy and birth are increased with ART, both because of multiple embryo transfer and embryo splitting. There is evidence of an increase in chromosomal abnormalities among pregnancies conceived using intracytoplasmic sperm injection and low birth weight and preterm delivery among singletons conceived with all types of ART; however, there remains uncertainty about whether these risks stem from the treatment or the parental infertility. For some outcomes, data of an increased risk with ART are suggestive at best largely because of lack of purposeful study of sufficient size and scope. These include specific perinatal morbidities, birth defects, developmental disabilities, and retinoblastoma. The evidence for an association between ART and spontaneous abortion is inconsistent and weak. There is inconclusive evidence that ART may be associated with genetic imprinting disorders. For childhood cancer, chronic conditions, learning and behavioral disorders, and reproductive effects there is insufficient empirical research to date, but given the data for more proximal outcomes, these outcomes merit further study. Future research needs to address the unique methodological challenges underlying study in this area.

Fetal Reduction From Twins to a Singleton

OBJECTIVE

In the past, our group took the position that we would not provide multifetal pregnancy reduction to a singleton regardless of starting number except for serious maternal medical indications or as a selective termination for diagnosed fetal anomalies. With evidence of increased safety and more women (many aged 40 years or more) asking for counseling about reduction to a singleton, we reviewed our prior reasoning.

METHODS

We compared outcomes of 52 first-trimester twin-to-singleton for multifetal pregnancy reduction cases performed by a single operator to twin and singleton data from recent national register studies.

RESULTS

Twin-to-singleton reductions represent less than 3% of all cases. Forty of 52 patients were aged 35 years or more, 19 were aged more than 40 years, and 2 were aged more than 50 years (age range 32-54 years). Since 1999, 23 of 28 had chorionic villus sampling before multifetal pregnancy reduction. Fifty-one of 52 reached viability with mean gestational age at delivery of 37.2 weeks. One of 52 patients miscarried (1.9%). Compared with multiple sources of data for twins, the loss rate is lower in twins reduced to a singleton.

CONCLUSION

Until recently, multifetal pregnancy reductions to a singleton were rare. Physicians were concerned about the unknown risks of multifetal pregnancy reduction in this situation. They also had moral doubts about the justification to go "below twins." However, physicians know that spontaneous twin pregnancy losses average 8-10%. Also, with experience, multifetal pregnancy reduction has become very safe in our hands. Our data suggest that the likelihood of taking home a baby is higher after reduction than remaining with twins. We propose that twin-to-singleton reductions might be considered with appropriate constraints and safeguards.

Effects of culture conditions on IVF outcome

Although in vitro fertilization (IVF) success rates have improved over the past decade, multiple pregnancies have become a formidable problem. The solution to this problem seems simple by mandating the reduction in numbers of embryos transferred. However, this is typically not accomplished without a compromise in the pregnancy rate. There have been a number of approaches designed to address high order multiple pregnancies from multi factorial analysis of early cleavage stage embryos to the development of extended culture systems, both of which require manipulations in the culture environment. Manipulations in embryo culture environment may not be benign. Several studies have demonstrated that adverse culture conditions have effects on gene expression and imprinting. Studies have also demonstrated that singleton human IVF babies have lower birth weight and higher incidence of congenital anomalies than natural conception babies. All of these factors need to be considered in relation to long term viability of IVF babies and the Barker hypothesis.

Pregnancy course and outcome after intracytoplasmic sperm injection: a controlled, prospective cohort study

OBJECTIVE

To determine pregnancy course and major malformation rate after intracytoplasmic sperm injection (ICSI).

DESIGN

Prospective, controlled, multicenter, nationwide German cohort study.

SETTING

Tertiary infertility centers in Germany.

PATIENT(S)

Three thousand three hundred seventy-two children and fetuses and 8,016 children and fetuses after the 16th week of gestation in pregnancies after ICSI and natural conception, respectively.

INTERVENTION(S)

Standardized prospective follow-up.

MAIN OUTCOME MEASURE(S)

Major malformation rate.

RESULT(S)

The major malformation rate was 8.7% (295/3,372) for the ICSI cohort and 6.1% (488/8,016) for the population-based control cohort (relative risk, 1.44 [1.25-1.65]). After adjustment for risk factors, the risk declined (adjusted odds ratio, 1.24 [95% CI, 1.02-1.50]). Regarding singletons, there was a significant difference for birth weight and gestational age, with a higher number of preterm and low birth weight children in pregnancies achieved after ICSI.

CONCLUSION(S)

Children who are born after intracytoplasmic sperm injection have an increased risk of a major congenital malformation compared with those born after spontaneous conception. This risk is mainly due to paternal and maternal risk factors, which are more prevalent in couples who use ICSI for reproduction. An infertility-linked risk is highly probable for the observed findings. A technique-related risk, however, cannot be ruled out.

Endometriosis and the outcome of in vitro fertilization

A generalized reproductive dysfunction rather than endometriotic implants is likely to have an impact on the outcome of IVF.

Recent decelerated decline in perinatal mortality rate of unlike-sexed twins in Japan

The effect of assisted reproductive technology is more pronounced in unlike-sexed twins than in like-sexed. Trends in perinatal mortality of twins were compared between the two types of sex combination. Certificates for births (478,276 cases), stillbirths (50,542 cases), and early neonatal deaths (8747 cases) were the subjects of this analysis. Since 1984, the decline in the perinatal mortality of unlike-sexed twins has been slower than that of like-sexed twins. In both light-for-dates (LFD) and non-LFD, the decline in the gestational age standardised mortality ratio has been slower in unlike-sexed twins. We suggest this is due to the introduction of assisted reproductive technologies.

Are major defects in children conceived in vitro due to innate problems in patients or to induced genetic damage?

Birth anomalies recently detected in epidemiological studies indicate greater risks following assisted human reproduction than with natural conception. Some of these conclusions and assumptions are questioned in this paper, and the effects of specific causative factors unique to some infertile couples are analysed. Other recent studies have identified imprinting defects as causes of birth disorders following IVF or intracytoplasmic sperm injection. While few in numbers, they apparently involve unusual factors in conception such as aberrant responses among preimplantation embryos to culture medium or serum. Various genetic and developmental factors in infertile couples influencing the origin of such birth outcomes are assessed, and the significance of imprinting and its embryological roles are discussed.

Preimplantation genetic diagnosis of human congenital heart malformation and Holt-Oram syndrome

Holt-Oram syndrome (HOS) is a multiple malformation syndrome associated with congenital heart malformation (CHM) and caused by mutations in the TBX5 transcription factor. Effective prenatal genetic diagnosis of HOS is limited by factors that modify clinical manifestations and confound prediction of an individual's phenotype. Although preimplantation genetic diagnosis (PGD) has been applied to complex disorders with some cardiovascular manifestations, its utility in Mendelian CHM has not been previously demonstrated. We tested whether PGD and in vitro fertilization (IVF) technology, including oocyte donation, can identify fertilized eggs affected by HOS for potential embryo selection. Five donor oocytes were fertilized in vitro with sperm from a HOS patient heterozygous for a Glu69ter-TBX5 mutation and then underwent embryo biopsy and genotyping. One carried the Glu69ter-TBX5 mutation; all others had wildtype genotypes. Two wildtype blastocysts were transferred to the mother, and the resulting singleton pregnancy was successfully delivered. Mutational analysis of fetal amniocytes and postpartum umbilical cord blood confirmed PGD. Fetal ultrasonography as well as postpartum electrocardiography and echocardiography also validated accurate prediction of normal skeletal and cardiac phenotypes. We conclude that PGD is an effective reproductive strategy for HOS patients. As more genetic etiologies for CHM are identified, application of PGD as adjunctive therapy to IVF will be increasingly available to prevent transmission of such diseases from affected parents to their children. Clinical application of PGD must balance the benefits of avoiding disease transmission with the medical risks and financial burdens of IVF.

Long-term effect of in vitro culture of mouse embryos with serum on mRNA expression of imprinting genes, development, and behavior

The long-term developmental and behavioral consequences of mammalian embryo culture are unknown. By altering the culture medium with the addition of FCS, we wanted to determine whether mouse embryos cultured under suboptimal conditions develop aberrant mRNA expression of imprinting genes at the blastocyst stage and whether fetal development, growth, and behavior of adult mice are affected. One-cell embryos obtained from superovulated female B6CBAF(1) mice were cultured for 4 days in K(+)-modified simplex optimized medium in the presence of either 10% FCS or 1 g/liter BSA. After embryo transfer, born animals were submitted to several developmental and behavior tests. The mRNA expression of some imprinting genes was significantly affected in blastocysts cultured in the presence of FCS. Two of the eight measures of preweaning development and some specific measures of neuromotor development, such as the walking activity, were delayed in the group originated with FCS. After 34 weeks, the weight of female mice cultured in vitro in the presence of FCS was significantly higher than controls. In addition, the locomotion activity of mice was altered at 5 and 15 months. Anatomopathological and histological analysis of animals at 20 months of age showed some large organs and an increase in pathologies. We have found that mice derived from embryos cultured with FCS exhibited specific behavioral alterations in anxiety and displayed deficiencies in implicit memories. Our data indicate that long-term programming of postnatal development, growth, and physiology can be affected irreversibly during the preimplantation period of embryo development by suboptimal in vitro culture.

Epigenetics and assisted reproductive technology: a call for investigation

A surprising set of recent observations suggests a link between assisted reproductive technology (ART) and epigenetic errors--that is, errors involving information other than DNA sequence that is heritable during cell division. An apparent association with ART was found in registries of children with Beckwith-Wiedemann syndrome, Angelman syndrome, and retinoblastoma. Here, we review the epidemiology and molecular biology behind these studies and those of relevant model systems, and we highlight the need for investigation of two major questions: (1) large-scale case-control studies of ART outcomes, including long-term assessment of the incidence of birth defects and cancer, and (2) investigation of the relationship between epigenetic errors in both offspring and parents, the specific methods of ART used, and the underlying infertility diagnoses. In addition, the components of proprietary commercial media used in ART procedures must be fully and publicly disclosed, so that factors such as methionine content can be assessed, given the relationship in animal studies between methionine exposure and epigenetic changes.

Center differences and outcomes of extremely low birth weight infants

OBJECTIVE

Previous multicenter studies have shown significant center differences in neonatal characteristics and morbidities. This study evaluated center differences in outcome at 18 to 22 months among extremely low birth weight (ELBW; 401-1000 g) infants after adjusting for demographics and antenatal interventions, and it identified neonatal interventions associated with outcome differences.

METHODS

We assessed the outcome of 2478 liveborn infants who were admitted in 1993 and 1994 to the 12 centers of the Neonatal Research Network of the National Institute of Child Health and Human Development; 1483 (60%) infants survived to 18 to 22 months, and 1151 (78%) had comprehensive evaluations. Logistic regression analyses were performed to identify center differences and the association of 4 neonatal interventions--active resuscitation, postnatal steroids, ventilator treatment for < or =27 days, and full enteral feedings < or =24 days--with adverse outcomes (cerebral palsy, low Bayley scores, and neurodevelopmental impairment [NDI]), after adjusting for demographics and antenatal interventions.

RESULTS

Using bivariate analyses, significant center differences were identified for mortality, antenatal and postnatal interventions, social and environmental variables, neonatal morbidities, and neurodevelopmental outcomes for the 12 centers. After adjustment for maternal and infant demographics and antenatal interventions, the percentage of ELBW infants who had died or had NDI at 18 to 22 months ranged from 52% to 85%. Active resuscitation and postnatal steroids were associated with increases of NDI of 11.8% and 19.3%, whereas shorter ventilation support and shorter time to achieve full enteral feeds were associated with decreases in NDI of 20.7% and 17.3%, respectively.

CONCLUSION

There are large and disturbing differences among centers in outcomes at 18 to 22 months after adjusting for demographic and antenatal interventions. Center differences in postnatal interventions associated with differences in outcome can provide hypotheses for testing in clinical trials to improve outcome.

Genetically modified laboratory animals--what welfare problems do they face?

In this article, we respond to public concern expressed about the welfare of genetically modified (GM) nonhuman animals. As a contribution to the debate on this subject, we attempt in this article to determine in what situations the practice of genetic modification in rodents may generate significant welfare problems. After a brief discussion of the principles of animal welfare, we focus on the problem of animal suffering and review some types of gene modifications likely to cause predictable welfare problems. In this article, we also consider suffering that may be involved in the process of generating GM animals. Finally, we discuss the role of GM animals in attempts to reduce, replace, and refine the use of animals in research.

Risk factors for adverse outcomes in spontaneous versus assisted conception twin pregnancies

OBJECTIVE

To evaluate risk factors for adverse outcomes in spontaneous vs. assisted conception twin pregnancies.

DESIGN

Historical cohort study.

SETTING

Four academic tertiary medical centers.

PATIENT(S)

Women with twin pregnancies, including 2,143 spontaneous and 424 assisted conception; 2,492 nonreduced and 75 reduced.

INTERVENTION(S)

None (observational).

MAIN OUTCOME MEASURE(S)

Preeclampsia, preterm premature rupture of membranes, birth <32 weeks and <30 weeks, low birth weight, very low birth weight, and slowed midgestation fetal growth (<10th percentile between 20 and 28 weeks).

RESULT(S)

Among nonreduced pregnancies, assisted conception was not significantly associated with any adverse outcomes; among nulliparas, the risk for preeclampsia was increased regardless of method of conception; among spontaneous conceptions, the risks for preterm premature rupture of membranes, low birth weight, very low birth weight, and slowed midgestation fetal growth were increased. Among all pregnancies, fetal reduction increased risks for birth <32 weeks and <30 weeks, low birth weight, very low birth weight, and slowed midgestation fetal growth. Among nulliparas with assisted conceptions, fetal reduction increased the risks for birth <30 weeks, very low birth weight, and slowed midgestation fetal growth.

CONCLUSION(S)

These findings indicate that in twin pregnancies, assisted conception is not a risk factor for adverse outcomes, but rather specific factors that are more common among these pregnancies, such as nulliparity and fetal reduction, increase risks.

Les enfants de l’ICSI sous la loupe

The debate concerning the health of children conceived by artificial reproduction technology (ART) continues. Among these techniques, intracytoplasmic sperm injection (ICSI) is the subject of most attention. Indeed, several studies have concentrated on the evaluation of risks associated with ICSI. The publication of a few recent articles on the subject is providing an opportunity to reconsider the situation. Generally, women conceiving via ART are older, more often primipar and present increased rates of uterine pathologies compared to women conceiving naturally. Furthermore, ART pregnancies are sources of anxiety resulting in a significant increase rates of caesarean section. ART children present an increased risk of low birth rate often linked to multiple pregnancy, but this is also true for singleton pregnancy. Major studies have not revealed a significantly increased rate of malformations in ICSI children. However, sporadic observations of errors in genomic imprinting or of rare tumors in children conceived by ICSI point to a need for increased vigilance of ICSI practices. Finally, the mental development, the family and social life of ICSI children appears similar to children conceived naturally.

On a fallacious invocation of the Barker hypothesis of anomalies in newborn rats due to mothers' food restriction in preimplantation phases

A statistical re-evaluation indicates serious flaws in the paper by Kwong et al., reporting that low birthweight and impaired development, and perhaps anomalous preimplantation embryo growth, were associated with food restriction during the preimplantation period. This paper has been used to confirm that early forms of protein deprivation in the preimplantation phase carry risks to IVF children. Errors in interpreting the nature of their study and a failure to apply the correct principles of statistical analysis in their hierarchical data structure have led to their flawed investigation. It is therefore proposed that such serious flaws cast doubt on their conclusions. The findings reported in this study should be withdrawn, and a rigorous statistical evaluation should be carried out to provide a proper assessment of the data.

Perinatal Outcomes in Singletons Following In Vitro Fertilization: A Meta-Analysis

OBJECTIVE

To estimate whether singleton pregnancies following in vitro fertilization (IVF) are at higher risk of perinatal mortality, preterm delivery, small for gestational age, and low or very low birth weight compared with spontaneous conceptions in studies that adjusted for age and parity.

DATA SOURCES

We searched MEDLINE, BIOSIS, Doctoral Dissertations On-Line, bibliographies, and conference proceedings for studies from 1978-2002 using the terms "in vitro fertilization," "female infertility therapy," and "reproductive techniques" combined with "fetal death," "mortality," "fetal growth restriction," "small for gestational age," "birth weight," "premature labor," "pre-term delivery," "infant," "obstetric," "perinatal," and "neonatal."

METHODS OF STUDY SELECTION

Inclusion criteria were singleton pregnancies following IVF compared with spontaneous conceptions, control for maternal age and parity; 1 of the above outcomes; and risk ratios or data to determine them. Study selection and data abstraction were performed in duplicate after removing identifying information.

TABULATION, INTEGRATION, AND RESULTS

Fifteen studies comprising 12,283 IVF and 1.9 million spontaneously conceived singletons were identified. Random-effects meta-analysis was performed. Compared with spontaneous conceptions, IVF singleton pregnancies were associated with significantly higher odds of each of the perinatal outcomes examined: perinatal mortality (odds ratio [OR] 2.2; 95% confidence interval [CI] 1.6, 3.0), preterm delivery (OR 2.0; 95% CI 1.7, 2.2), low birth weight (OR 1.8; 95% CI 1.4, 2.2), very low birth weight (OR 2.7; 95% CI 2.3, 3.1), and small for gestational age (OR 1.6; 95% CI 1.3, 2.0). Statistical heterogeneity was noted only for preterm delivery and low birth weight. Sensitivity analyses revealed no significant changes in results. Early preterm delivery, spontaneous preterm delivery, placenta previa, gestational diabetes, preeclampsia, and neonatal intensive care admission were also significantly more prevalent in the IVF group.

CONCLUSION

In vitro fertilization patients should be advised of the increased risk for adverse perinatal outcomes. Obstetricians should not only manage these pregnancies as high risk but also avoid iatrogenic harm caused by elective preterm labor induction or cesarean.

The desire of infertile patients for multiple births

OBJECTIVE

To determine the proportion of infertile women who prefer a multiple birth over a singleton, patient characteristics associated with this desire, and patient knowledge about the risks of multiple births.

DESIGN

Prospective analysis.

SETTING

Academic university hospital-based infertility center and private general gynecology clinic.

PATIENT(S)

Four hundred sixty-four female patients with infertility who presented for their initial visit.

MAIN OUTCOME MEASURE(S)

Demographic characteristics, infertility history, desire regarding multiple births, knowledge of the risks of multiple births, and goals of infertility evaluation and treatment were determined by using a 41-question survey. Univariate analysis was performed to assess patient characteristics associated with the desire for multiple births. Independent factors associated with this desire were assessed by multivariable logistic regression analysis.

RESULT(S)

20.3% of women desired multiples over a singleton gestation. Nulliparity, lower family income, younger patient age, prior evaluation for infertility, longer duration of infertility, and lack of knowledge regarding risks of twin gestations were associated with this desire. Only nulliparity and lower family income were independently associated.

CONCLUSION(S)

A sizable minority of infertility patients prefers a multiple birth as their treatment outcome. Patient education may be an effective strategy to reduce the incidence of twin and higher-order multiple pregnancies.

The association of parity with mortality outcomes among triplets

OBJECTIVE

The purpose of this study was to evaluate the association of parity with stillbirth and neonatal and infant death among triplets.

STUDY DESIGN

This was a retrospective cohort study of 15,930 triplets who were delivered in the United States between 1995 and 1997. Infants of nulliparous mothers were compared with infants of multiparous mothers. Adjusted relative risks for death by parity were computed with the use of the generalized estimating equations framework.

RESULTS

The likelihood for stillbirth (odds ratio, 3.40; 95% CI, 2.20-5.26) was significantly greater among nulliparous mothers. Neonatal (odds ratio, 1.17; 95% CI, 0.95-1.43) and infant mortality rates (odds ratio, 1.10; 95% CI, 0.92-1.32) were comparable, however. With an increase in parity, there was a consistent declining trend in the risk for stillbirth (P<.0001).

CONCLUSION

Nulliparity more than triples the risk for intrauterine fetal death among triplets. This parity-related disparity underscores the need for care providers to be particularly concerned about triplet gestations among nulliparous mothers.

Early mortality among triplets in the United States: black-white disparity

OBJECTIVE

In this study, we sought to estimate the black-white gap in early mortality among triplets.

STUDY DESIGN

This was a retrospective cohort study on triplets delivered in the United States from 1995 to 1997. We computed relative risks for early mortality among triplets born to black mothers using the generalized estimating equation framework.

RESULTS

There were 1317 black and 14,364 white triplets analyzed. Black triplets were twice as likely to have neonatal and infant mortality compared with whites (Odds ratio [OR], 2.00, 95% CI, 1.38-2.77; and OR, 2.20, 95% CI, 1.59-3.00, respectively). The widest disparity was observed postneonatally, with black triplets sustaining a level of risk almost 4-fold that of whites (OR, 3.60, 95% CI, 2.10-6.10). Stillbirth and perinatal mortality were comparable for both races.

CONCLUSION

Black-white disparity for early mortality among triplets was widest postneonatally. This finding bears important clinical and public health implications.

Increased Infertility With Age in Men and Women

OBJECTIVE

To estimate the effects of aging on the percentage of outwardly healthy couples who are sterile (completely unable to conceive without assisted reproduction) or infertile (unable to conceive within a year of unprotected intercourse).

METHODS

A prospective fecundability study was conducted in a sample of 782 couples recruited from 7 European centers for natural family planning. Women aged 18-40 years were eligible. Daily intercourse records were used to adjust for timing and frequency of intercourse when estimating the per-menstrual-cycle probability of conception. The number of menstrual cycles required to conceive a clinical pregnancy and the probability of sterility and infertility were derived from the estimated fecundability distributions for men and women of different ages.

RESULTS

Sterility was estimated at about 1%; this percent did not change with age. The percentage infertility was estimated at 8% for women aged 19-26 years, 13-14% for women aged 27-34 years and 18% for women aged 35-39 years. Starting in the late 30s, male age was an important factor, with the percentage failing to conceive within 12 cycles increasing from an estimated 18-28% between ages 35 and 40 years. The estimated percentage of infertile couples that would be able to conceive after an additional 12 cycles of trying varied from 43-63% depending on age.

CONCLUSION

Increased infertility in older couples is attributable primarily to declines in fertility rates rather than to absolute sterility. Many infertile couples will conceive if they try for an additional year.

Assisted reproductive technology and congenital overgrowth: Some speculations on a case of Pallister-Killian syndrome

We report on a boy with Pallister-Killian syndrome (PKS) who was conceived by assisted reproductive technology (ART), specifically in vitro fertilization (IVF) with parents' gametes. A prenatal diagnosis performed elsewhere by CVS failed to detect the presence of the isochromosome 12p that was demonstrated postnatally in approximately 50% of cultured skin fibroblasts. Given that the patient did not show the congenital overgrowth typical of PKS, we speculate that ART might have restricted overgrowth in this particular case. More broadly, we hypothesize that overgrowth might protect from early demise fetuses conceived by ART, a technology known to cause low and very low birth weight.

Society for Reproductive Biology Founders' Lecture 2003.The making of an embryo: short-term goals and long-term implications

During early development, the eutherian mammalian embryo forms a blastocyst comprising an outer trophectoderm epithelium and enclosed inner cell mass (ICM). The short-term goal of blastocyst morphogenesis, including epithelial differentiation and segregation of the ICM, is mainly regulated autonomously and comprises a combination of temporally controlled gene expression, cell polarisation, differentiative cell divisions and cell–cell interactions. This aspect of blastocyst biogenesis is reviewed, focusing, in particular, on the maturation and role of cell adhesion systems. Early embryos are also sensitive to their environment, which can affect their developmental potential in diverse ways and may lead to long-term consequences relating to fetal or postnatal growth and physiology. Some current concepts of embryo–environment interactions, which may impact on future health, are also reviewed.