Obstetric and neonatal risk of pregnancies after assisted reproductive technology: a matched control study

BACKGROUND: The aim of the study was to evaluate the obstetric and neonatal outcome of pregnancies after assisted reproduction technology (ART) in comparison with matched controls from spontaneous pregnancies. METHODS: A total of 12 920 deliveries at the Department of Obstetrics and Gynecology, University of Szeged, from 1 January 1995 to 31 December 2001 were subjected to retrospective analysis. Two hundred and eighty-four singleton, 75 twin and 17 triplet pregnancies after ovulation induction (n = 114; 30.3%), intrauterine insemination (n = 33; 8.8%) and in vitro fertilization (n = 229; 60.9%) were evaluated. The pregnancy outcome of the singleton and twin pregnancies was compared with that for controls matched with regard to age, gravidity and parity and previous obstetric outcome after spontaneous pregnancies. RESULTS: Twenty-four percent of the assisted reproductive pregnancies were multiple pregnancies. The incidences of singleton intrauterine growth retardation (IUGR) and preterm birth were reasonably similar to those among the controls (IUGR: 6.3% vs. 4.2%; preterm births: 13.0% vs. 9.9%, for the cases and the controls, respectively). As compared with the controls, there was an increased incidence of cesarean section among the singleton (41.2% vs. 34.5%, p = 0.12; OR 1.33; 95% CI 0.95-1.87) and twin assisted reproduction pregnancies (66.7% vs. 60.0%), but without significant differences. CONCLUSIONS: Increased obstetric risk could be observed concerning threatened preterm delivery and cesarean section rate in the study group. The perinatal outcome of singleton and twin pregnancies following assisted reproductive techniques is comparable with that of spontaneously conceived, matched pregnancies.     

Pregnancy complications,obstetric risks,and neonatal outcome in singleton and twin pregnancies after GIFT and IVF

Purpose In vitro fertilization (IVF) and to a lower extent gamete intra-fallopian transfer (GIFT) have become routine infertility treatments in industrialized countries. Our purpose is to compare the obstetric and neonatal characteristics of singleton and twin pregnancies after GIFT and IVF with those conceived spontaneously.Methods This case-control study was conducted in a tertiary care medical center. The 322 singleton and 78 twin pregnancies after GIFT or IVF from 1991 through 1996 were evaluated and compared with each other, and with a control group that conceived spontaneously and matched for parity, maternal and gestational age. Statistical significance of differences was assessed by ² test or two-tailed Fisher exact test. Continuous variables were compared by the paired t-test.Results Pregnancy-induced hypertension (PIH) and vaginal bleeding were significantly more frequent maternal complications in the GIFT/IVF singleton groups compared to controls. In twin pregnancies the rate of cesarean sections, vaginal bleeding and preterm labor were more common after GIFT/IVF but did not reach statistical significance. Assisted reproduction was associated with low birth weight only in twin pregnancies when controlled for confounding variables, however perinatal outcome was comparable. There was no significant difference in the outcome measures between GIFT and IVF pregnancies.Conclusion After controlling for parity, maternal and gestational age, singleton pregnancies conceived by GIFT/IVF are at increased obstetrical risk, however the perinatal outcome is comparable despite a lower average birth weight.     

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.     

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.     

Is the obstetric outcome of in vitro fertilized singleton gestations different from natural ones? A controlled study

Objective: To determine whether singleton IVF pregnancies carry adverse maternal or fetal outcome when compared with naturally conceived gestations.

Design: An analysis of the obstetric outcome of singleton IVF pregnancies in comparison with matched, naturally conceived singleton controls. Setting: In vitro fertilization unit and obstetric service at a tertiary medical center.

Patient(s): Two hundred sixty consecutive singleton IVF pregnancies and 260 naturally conceived singleton controls matched 1:1 for maternal age, parity, ethnic origin, and location and date of delivery.

Intervention(s): In vitro fertilization-ET.

Main Outcome Measure(s): The rate of antenatal obstetric complications, nonvertex presentation, cesarean section, preterm labor, low birth weight, small and very small for gestational age, neonatal intensive care unit admissions, and perinatal mortality.

Result(s): The rates of most antenatal complications were similar in both groups. Urinary tract infection was the only complication diagnosed significantly more frequently after IVF (7.3% versus 1.2%); however, the rates of severe urinary tract infection necessitating hospitalization were similar. The incidence of nonvertex presentation was also similar. The cesarean section rate was significantly higher among IVF patients (41.9% versus 15.5%). The rates of preterm labor, low birth weight, small and very small for gestational age, neonatal intensive care unit admissions, and perinatal mortality were comparable.

Conclusion(s): When controlling for maternal age, parity, ethnic origin, and location and date of delivery, singleton IVF pregnancies do not carry an increased risk for prematurity, low birth weight, or maternal or fetal complications. Still, these pregnancies are associated with a high rate of cesarean sections.     

Obstetric outcome of in vitro fertilization pregnancies compared with normally conceived pregnancies.

OBJECTIVE: To compare the obstetric outcome of in vitro fertilization pregnancies with normally conceived pregnancies. STUDY DESIGN: The obstetric outcome of in vitro fertilization pregnancies achieved in 763 British residents at two in vitro fertilization clinics resulting in the births of 961 babies were compared by means of the relative risk statistic with a control group of naturally conceived primiparous pregnancies matched by maternal age and multiplicity of pregnancy. RESULTS: Twenty-five percent of in vitro fertilization pregnancies were multiple pregnancies. The incidence of singleton term breech presentation was similar to that among controls. As compared with controls there was an increased incidence among in vitro fertilization pregnancies of vaginal bleeding and hypertension requiring hospitalization (p less than 0.001) and cesarean births (p less than 0.001) and, among in vitro fertilization singleton pregnancies, an increased incidence of intrauterine growth retardation (p less than 0.05), placenta previa (p less than 0.05), and preterm delivery (p less than 0.001). The congenital malformation, stillbirth, and perinatal mortality rates were comparable with maternal age-standardized national rates. CONCLUSIONS: Although the majority of in vitro fertilization pregnancies have a satisfactory obstetric outcome, there are a number of increased obstetric risks that may reflect the history of infertility, the relatively high incidence of poor obstetric history, and the lower threshold for obstetric intervention in in vitro fertilization patients.     

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.     

体外受精-胚胎移植后妊娠产科结局分析

目的　研究体外受精 胚胎移植 (IVF ET)术后妊娠的母儿围生期特点。方法　采用病例对照方法 ,选择行IVF ET术后妊娠并于 1993年 1月至 2 0 0 2年 12月分娩的妇女 2 5 5例 ,与同期分娩的自然受孕的妇女17175例对照 ,研究IVF ET术后妊娠的围生期情况。结果　IVF ET单胎妊娠的早产、前置胎盘、糖耐量试验(OGTT)异常、产后出血、剖宫产率高于自然受孕组 ,P <0 0 5。IVF ET双胎妊娠的分娩孕周、新生儿体重低于单胎妊娠 ,P <0 0 5 ;中度及重度妊娠期高血压疾病 (妊高征 )、胎膜早破发生率高于单胎妊娠 ,P <0 0 5。结论　IVF ET妊娠是高危妊娠 ,多胎妊娠率高是导致早产和低体重儿显著增多的主要原因 ,加强孕期保健 ,及时治疗并发症可获得良好的妊娠结局。     

Reduction of twin pregnancy to singleton: does it improve pregnancy outcome?

Objective.?To compare pregnancy complications, obstetrical and neonatal outcome of twin pregnancies reduced to singleton, with both non-reduced twin pregnancies and singleton pregnancies.

Methods.?A retrospective case–control study was performed at the Obstetrics and Gynecology Ultrasound unit of a tertiary referral medical center. Patient's population included 32 bi-chorionic bi-amniotic twin pregnancies reduced to singleton and 35 non-reduced twin pregnancies. Thirty-six patients with singleton pregnancies comprised the second control group. Main outcome measures were rates of pregnancy complications, preterm delivery (both before 37 weeks of gestation and before 34 weeks of gestation), late abortions, intra-uterine growth retardation, cesarean section, mean birth weights, and mean gestational age at delivery.

Results.?The reduced twin pregnancies group had similar rates of total pregnancy complications, preterm deliveries, and cesarean section as non-reduced twins. Gestational age at delivery and mean birth weight were also similar to non-reduced twins and significantly different compared with singletons. Preterm delivery and late abortion incidences were significantly higher when reduction was beyond 15 weeks gestation.

Conclusions.?Reduction of twin pregnancy to singleton does not change significantly pregnancy course and outcome. Favorable obstetrical and neonatal outcomes could be achieved by performing early, first trimester reductions.     

Perinatal outcomes of in vitro fertilization twins: a systematic review and meta-analyses

OBJECTIVE: Uncontrolled studies suggest that in vitro fertilization twins have increased rates of preterm birth and low birth weight and would warrant increased antenatal monitoring. The objective of this meta-analysis was to determine whether the incidence of poor obstetric outcomes is higher for in vitro fertilization twins than for spontaneously conceived twins who were matched for maternal age. STUDY DESIGN: Medline and EMBASE were searched with comprehensive search strategies. Case-control and cohort studies of twins who were conceived by in vitro fertilization or in vitro fertilization/intracytoplasmic sperm injection, with the transfer of fresh embryos or cryopreserved (frozen) in women with infertility, and/or whose partners were subfertile or infertile, compared with naturally (spontaneously) conceived twins who were matched for maternal age (case-control studies) or which were controlled for it (cohort studies). Two reviewers independently assessed titles, abstracts, and study quality and extracted the data. Statistical analysis was performed with commercial statistical software. Dichotomous data were meta-analyzed with odds ratios as measures of effect size, and continuous data was meta-analyzed with mean differences. Interstudy variation was incorporated with the assumption of a random effects model for the treatment effect. RESULTS: Compared with spontaneously conceived twins who were matched for maternal age, in vitro fertilization twins have an increased risk of preterm birth between 32 and 36 weeks of gestation (odds ratio, 1.48; 95% CI, 1.05-2.10), and an elevated risk of preterm birth at <37 weeks of gestation when parity is also matched for an odds ratio of 1.57 (95% CI, 1.01-2.44). There was an increased rate of cesarean delivery among in vitro fertilization twins (odds ratio, 1.33; 95% CI, 1.06-1.67). There were no significant differences in incidences of perinatal death, low birth weight infants, or congenital malformations. CONCLUSION: In vitro fertilization twins have increased rates of preterm birth compared with spontaneously conceived twins who were matched for maternal age, despite the fact that their outcomes would be expected to be better because of the decreased proportion of monochorionic twins.     

Obstetric outcome of twin pregnancies conceived by in vitro fertilization and ovulation induction compared with those conceived spontaneously

OBJECTIVE: To compare the obstetric characteristics of twin pregnancies conceived by in vitro fertilization (IVF) and ovulation induction with those conceived spontaneously. DESIGN: Case control study. SETTING: Tertiary Medical Center. PATIENTS: All twin deliveries that were achieved by IVF (n=558) and ovulation induction (n=478) from January 1988 through December 2002 were evaluated. Each group was compared with a control group that conceived spontaneously (n=3694) and was delivered during the same period. INTERVENTIONS: Ovulation induction, IVF-ET. MAIN OUTCOME MEASURES: Obstetrical complications. RESULTS: Multivariate analysis showed that patients who conceived with the assistance of IVF and ovulation induction had a significantly higher risk for gestational diabetes mellitus (odds ratio [OR]=2.41, 95% confidence interval [CI]=1.77-3.29 and OR=1.71, CI=1.2-2.42, respectively), cesarean section (OR=2.17, 95% CI=1.74-2.70 and OR=1.76, CI=1.43-2.16, respectively), and a lower gestational age at birth in the IVF group (OR=0.91, 95% CI=0.88-0.94), compared with their controls. CONCLUSIONS: After controlling for maternal age, and nulliparity we demonstrated that twin pregnancies conceived with the assistance of IVF and ovulation induction are at increased risk for gestational diabetes mellitus, and delivery by cesarean section. In addition, IVF conceived pregnancies have a lower gestational age at birth.     

辅助生育技术受孕双胎与自然受孕双胎妊娠结局的分析

目的　探讨辅助生育技术受孕 (助孕 )双胎与自然受孕双胎围产期的结局。方法　选择 10 4例助孕双胎孕妇 (助孕组 )和 173例自然受孕双胎孕妇 (自然受孕组 ) ,比较两组孕妇一般情况、妊娠合并症、分娩情况和新生儿预后等方面的差异。结果　 (1)助孕组孕妇平均年龄 (31 2± 3 7)岁 ,自然受孕组孕妇为 (2 7 8± 3 5 )岁 ,两组比较 ,差异有显著性 (P <0 0 5 )。 (2 )助孕组孕妇早产 70例(6 7 3% ) ,自然受孕组孕妇早产 78例 (45 1% ) ,两组比较 ,差异有极显著性 (P <0 0 1)。助孕组孕妇患妊娠期糖尿病或糖耐量异常 16例 (15 4 % ) ,自然受孕组孕妇仅 4例 (2 3% ) ,两组比较 ,差异有极显著性 (P <0 0 1)。(3)助孕组孕妇剖宫产率为 76 0 % (79/10 4 ) ,明显高于自然受孕组的 6 5 3% (113/173)。(4)两组围产儿死亡率、畸形发生率和新生儿窒息率等比较 ,差异无显著性 (P <0 0 5 )。结论　助孕双胎孕妇年龄较大 ,早产率及妊娠期糖尿病或糖耐量异常发生率高 ;分娩方式以剖宫产为主。助孕双胎孕妇的围产儿结局与自然受孕双胎相似     

Analysis of 104 twin pregnancies conceived with assisted reproductive technologies and 193 spontaneously conceived twin pregnancies

OBJECTIVE: To evaluate pregnancy outcome of assisted reproductive technology (ART)-conceived twin pregnancies. DESIGN: Retrospective study. SETTING: A tertiary obstetric care center. PATIENT(S): All twin pregnancies delivered > or = 24 weeks of gestation from January 1, 1996, to December 31, 1997. INTERVENTION(S): Maternal and neonatal record review. MAIN OUTCOME MEASURE(S): Pregnancy and perinatal outcome. RESULT(S): The study group comprised 104 ART-conceived twin pregnancies, and 193 non-ART-conceived pregnancies served as controls. Mean maternal age, the proportion of nulliparae, and the percentage of women who delivered before 34 weeks' gestation was higher among the study women, whereas mean gestational age was younger. The incidences of pregnancy-induced hypertension, uterine bleeding, premature contractions, intrauterine growth retardation, fetal death, discordance, and cesarean section were significantly higher in the study group. Correspondingly, in the study group, the mean birth weight of both twins was lower; more neonates weighed < 1, 500 g, more had Apgar scores of < 7 at 5 minutes, more were admitted to the intensive care unit, and more second twin neonates died. The outcome of twin pregnancies conceived spontaneously was comparable with those conceived by ovulation induction. CONCLUSION(S): Assisted reproductive technology-conceived twin pregnancies are at greater risk than non-ART-conceived ones for pregnancy complications and adverse perinatal outcome.     

The association of in vitro fertilization and perinatal morbidity

In recent years, there has been increasing concern regarding the safety of in vitro fertilization (IVF) because of the potential health impact on these infants. Multiple pregnancy contributes the vast majority of morbidity associated with IVF and, initially, many thought that adverse outcomes after IVF were solely attributable to the high incidence of twin pregnancies. More recently, multiple studies have suggested that IVF singleton pregnancies may be at increased risk for preterm birth, low birth weight, congenital anomalies, perinatal mortality, and several other pregnancy-related complications compared with unassisted singleton pregnancies. We have focused this review on the increased risk of adverse outcomes in IVF singleton conceptions compared with that of unassisted conceptions. The available evidence evaluating the association between IVF and low birth weight, preterm delivery, placental abruption, preeclampsia, congenital anomalies, and perinatal mortality in singleton pregnancies is summarized. In addition, data reporting an increased risk of congenital and chromosomal anomalies after IVF are presented.     

Perinatal Outcome of Pregnancies After Assisted Reproduction: A Case–Control Study

Purpose: A matched case–control study of all pregnancies obtained after either IVF or ICSI was conducted to investigate the perinatal outcome. Methods: Three hundred eleven singleton and 115 twin pregnancies obtained after assisted reproduction were studied. Controls were selected from a regional register and were matched for maternal age, parity, singleton or twin pregnancy, and date of delivery. Results: No significant difference was observed for gestational age at delivery, birth weight, incidence of congenital anomalies, and incidence of perinatal mortality between ART (singleton and twin) pregnancies and spontaneous controls. ART twin pregnancies showed a higher incidence of preterm deliveries than control pregnancies (52 vs 42%; P < 0.05) and needed more neonatal intensive care (47 vs 26%; P < 0.05). Conclusions: From this case–control study it is concluded that the perinatal outcome of ART singleton pregnancies is not different from that in matched controls. ART twin pregnancies showed a higher incidence of preterm deliveries than control pregnancies and needed more neonatal intensive care.     

Infertility treatment is an independent risk factor for cesarean section among nulliparous women aged 40 and above

OBJECTIVE: To determine whether nulliparous women > 40 years old with singleton pregnancies who conceived after infertility treatment are at an increased risk for cesarean section compared with older nulliparous patients who conceived spontaneously. STUDY DESIGN: All subjects in this study were nulliparous women > 40 years old with singleton gestations who were delivered of their infants between 1990 and 1998. The Mantel-Haenszel procedure was used to obtain the weighted odds ratios and to control for confounding variables. RESULTS: During the study period, 115 nulliparous women > 40 years old with singleton pregnancies were delivered of their infants in our institute. Of those, 80 pregnancies were spontaneous and 35 pregnancies occurred after infertility treatment. Women treated for infertility had a higher rate of low-birth-weight (< 2500 g) newborns (34.3% versus 10.1%; odds ratio, 4.7; 95% CI, 1.5 to 14.6; P = .002). No other statistically significant demographic and obstetric differences were found between the groups. There were no cases of perinatal death in the study population. Women treated for infertility had statistically significant higher rates of cesarean section compared with those who conceived spontaneously (71.4% versus 41.3%; odds ratio, 3.6; 95% CI, 1.4 to 9.2; P =.002). Stratified analysis (the Mantel-Haenszel technique) was used to control for possible confounders such as low birth weight, pathologic presentations, failed induction, nonprogressive labor, and nonreassuring fetal heart rate tracings. None of those variables explained the higher incidence of cesarean section in the group treated for infertility. CONCLUSION: A history of infertility treatment among nulliparous women > 40 years old with singleton pregnancies increases the risk for cesarean delivery independently of other known risk factors.     

Maternal serum alpha-fetoprotein in twin pregnancies uncomplicated by neural tube defect

The maternal serum alpha-fetoprotein concentration was measured between 16 and 20 weeks in 145 twin pregnancies in which neither fetus had a neural tube defect. When the maternal serum alpha-fetoprotein concentration was less than two multiples of the singleton median, pregnancy outcome was good; the extended perinatal mortality rate was 32.6/1000, mean birth weights for the first and second twins were 2507 and 2443 gm, respectively, and mean gestation at delivery was 36 weeks, 6 days. When the maternal serum alpha-fetoprotein concentration was greater than four multiples of the singleton median, the outcome was poor; the extended perinatal mortality was 400/1000, mean birth weights were 1963 and 1523 gm, and mean gestation at delivery was 32 weeks, 4 days. The negative correlations of maternal serum alpha-fetoprotein concentration with birth weight and gestation at delivery were highly significant. Maternal serum alpha-fetoprotein concentration in midpregnancy is a useful predictor of outcome in twin pregnancy, independent of the occurrence of neural tube defect, and it appears to be related to the timing of delivery rather than fetal growth.     

Outcome of pregnancies achieved by in vitro fertilisation techniques and diagnosed as twins at the 6 week ultrasound

BACKGROUND: To bring the success rate of in vitro fertilisation (IVF) procedures to an acceptable level, multiple embryos have historically been replaced. This has resulted in an 'epidemic' of multiple births. The pendulum has now swung full circle and the number of embryos transferred is now being limited. Such high numbers of IVF twins will not be produced in the future. AIM: To review retrospectively the outcome of a series of pregnancies achieved by IVF where the 6 week ultrasound showed the presence of two sacs. METHODS: Retrospective study in a university IVF programme that produced 746 IVF pregnancies with twins at 6 weeks of gestation (1991-1999). RESULTS: The main outcome measures were perinatal mortality, pregnancy outcome, gestation at delivery and obstetrics complications reported. Interestingly, by 20 weeks gestation, 184 (24.7%) of pregnancies spontaneously reduced to a singleton, whereas 49 (6.6%) lost both twins. Of the 513 (68.8%) viable twin pregnancies (>20 weeks), 154 (20.6%) went on to term (>37 weeks), whereas 250 (33.5%) delivered between 33 and 36 weeks gestation. The perinatal mortality per 1000 births was 6.5 over 37 weeks, 8.0 for 33-36 weeks, 41.7 for 29-32 weeks and 500 for under 28 weeks.     

IVF twins have similar obstetric and neonatal outcome as spontaneously conceived twins: a prospective follow-up study

Studies comparing the outcome of spontaneous versus IVF twin pregnancies report heterogeneous results. This may depend on differences in the studied populations and/or in the management approach to twin pregnancy. The aim of the present study was to compare both maternal and perinatal outcomes in dichorionic diamniotic twin pregnancies who where spontaneously conceived or originated by successful homologous IVF. In order to get homogeneous observations, monochorionic twin pregnancies and triplet pregnancies were excluded. Moreover, to avoid any possible bias deriving from differences in the obstetric management, all pregnancies were managed by the same team applying fixed obstetric protocols. The study included 223 twin pregnancies, 84 conceived by IVF and 139 spontaneously conceived. Overall, maternal and perinatal outcomes were similar in the two groups: no significant differences were observed as far as gestational age at delivery, birthweight, perinatal morbidity and mortality, and rate of malformations were concerned. The rate of Caesarean section was slightly, but not significantly, higher in IVF pregnancies. In conclusion, the outcome of IVF twin pregnancies is comparable to that of spontaneously conceived twin pregnancies, provided that the same management criteria are applied.     

The vanishing twin: Diagnosis and implications

Vanishing twin syndrome (VTS), defined by first-trimester spontaneous loss of a twin, is a common phenomenon with a reported prevalence of 15–35% of twin pregnancies. The etiology of VTS is obscure. Still, several risk factors have been identified, including an increased number of embryos transferred in pregnancies conceived by in vitro fertilization, an initial increased number of gestational sacs and advanced maternal age.The effect of VTS on obstetric and perinatal outcomes is controversial. Several studies have reported that pregnancies with VTS were associated with increased risk for preterm birth and small for gestational age neonates compared to singleton pregnancies, while others showed no difference in perinatal outcomes.The prevalence of placental vascular and anatomic abnormalities such as small placentas was higher in VTS. These findings lay an essential foundation for understanding how this phenomenon affects obstetric and perinatal outcomes of the surviving pregnancy.