Perinatal outcome of pregnancies after assisted reproduction: a case-control study.

OBJECTIVE: We conducted a case-control study of all pregnancies obtained with assisted reproduction technology in the Dutch-speaking part of Belgium from 1992 until 1997 to investigate differences in peripartum obstetric events and the perinatal outcome. STUDY DESIGN: Three thousand fifty-seven singleton and 1241 twin pregnancies were studied. About 90% of pregnancies resulted from in vitro fertilization; the remainder resulted from intracytoplasmic sperm injection. Control subjects were selected from a regional register and were matched for maternal age, parity, fetal sex, plurality, and date of delivery. The main outcome measures were duration of gestation, birth weight, perinatal death, perinatal morbidity, incidence of congenital malformations, and incidence of cesarean delivery. RESULTS: Odds ratios and 95% confidence intervals were 2.6 (1.4-4.8) for perinatal mortality, 3.5 (2.2-5.7) for birth before 33 weeks of gestation, and 1.7 (1.5-1.9) for cesarean delivery in singleton pregnancies that resulted after in vitro fertilization. Twin pregnancies obtained with in vitro fertilization, on the contrary, were similar for all outcome measures, except for the incidence of cesarean delivery (odds ratio, 1.4; 95% confidence interval, 1.2-1.7) compared with spontaneously conceived twin pregnancies. CONCLUSION: The perinatal outcome of singleton pregnancies obtained with in vitro fertilization is significantly worse than that of spontaneously conceived pregnancies, mainly because of the increased rate of preterm birth. The outcome of twin pregnancies obtained with in vitro fertilization is comparable with that of normally conceived twins. For both singleton and twin pregnancies obtained with in vitro fertilization, the incidence of cesarean delivery is increased.     

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.     

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.     

Maternal risks and perinatal outcome in a Danish national cohort of 1005 twin pregnancies: the role of in vitro fertilization

BACKGROUND: Twin pregnancies constitute 25% of all in vitro fertilization (IVF) and intracytoplasmic sperm injection (ICSI) pregnancies. There is a lack of knowledge on maternal risks and perinatal outcome of IVF/ICSI twin pregnancies. METHODS: National survey by questionnaire (n = 1769). The study population consisted of all IVF/ICSI twin mothers (n = 266) and the two control groups of all IVF/ICSI singleton mothers (n = 764) and non-IVF/ICSI twin mothers (n = 739) who delivered in Denmark in 1997. The response rate was 89% among IVF twin mothers and overall 81%. RESULTS: In terms of maternal risks and perinatal outcome no significant differences were observed between IVF/ICSI twin and non-IVF/ICSI twin pregnancies after stratification for maternal age and parity. Nevertheless, IVF/ICSI twin mothers were more frequently on sick leave (OR 2.5, 95% CI 1.5-4.0) and hospitalized (OR 1.9, 95% CI 1.3-2.8) during pregnancy. Compared with IVF/ICSI singleton pregnancies, IVF/ICSI twin pregnancies were characterized by a higher incidence of preeclampsia (OR 2.4, 95% CI 1.5-4.2) and a higher frequency of sick leave (OR 6.8, 95% CI 4.4-10.5) and hospitalizations during pregnancy (OR 3.5, (95% CI 2.5-4.9); moreover, mean birthweight (p < 0.001) and gestational age (p < 0.001) were lower. No differences were observed in the incidence of pregnancy-induced hypertension and gestational diabetes between IVF/ICSI twin and singleton pregnancies. CONCLUSION: Although this population study indicates that maternal risks in IVF/ICSI twin pregnancies are comparable with non-IVF/ICSI twin pregnancies, the IVF/ICSI twin mothers were more likely to be on sick leave or hospitalized during pregnancy. Furthermore, maternal risks were higher and obstetric outcome poorer in IVF/ICSI twin vs. IVF/ICSI singleton 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 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.     

Obstetric outcomes in nulliparous women aged 35 and over with singleton pregnancies conceived by in vitro fertilization

Objective To investigate obstetric outcomes in singleton pregnancies conceived by in vitro fertilization (IVF) to nulliparous women older than 35 compared to those of their younger counterparts. Methods Nulliparous women 35 years and older at delivery conceived by IVF (n = 89) were compared with nulliparous women 34 years and younger at delivery conceived by IVF (n = 48). Data included antenatal data, gestational age at delivery, maternal and neonatal complications and mode of delivery. Results The incidence of pregnancy-induced hypertension in the younger group was significantly higher than that in the elderly group (13 vs. 3.4%, P = 0.043). There were no measurable differences in other obstetric outcomes such as placental abnormality, premature delivery or neonatal asphyxia between the two groups. Conclusion The current results suggest that obstetric complications in pregnancies conceived IVF are attributed to mechanisms other than those depend on advanced maternal age.     

Dilemma of increased obstetric risk in pregnancies following IVF-ET

Purpose : To determine the rates of pregnancy complications following in vitro fertilization in comparison with those in a matched control group. Methods : A total of 13,543 deliveries at the Department of Obstetrics and Gynecology, University of Szeged, between January 1, 1995 and February 28, 2002 were subjected to retrospective analysis. The 230 (1.7%) pregnancies following IVF-ET were evaluated and matched with spontaneous pregnancies concerning age, parity, gravidity, and previous obstetric outcome. Demographic and selected maternal characteristics, pregnancy and labor complications, and neonatal outcome were compared in the two groups. Results : The pregnancy complication rate was partly significantly higher among the singleton IVF-ET pregnancies. The obstetric risk was elevated, though not significantly concerning twin pregnancies. Conclusions : IVF-ET presents an additional obstetric risk. The neonatal outcome displays a significant difference only concerning an increased premature birth rate of singleton pregnancies. Triplet IVF-ET pregnancies involve a much higher risk of both pregnancy complications and neonatal outcome.     

Obstetric outcomes of elderly primiparous singleton pregnancies conceived by <Emphasis Type="Italic">in vitro</Emphasis> fertilization compared with those conceived spontaneously

Aim:  To examine the obstetric outcomes of elderly primiparous singleton pregnancies conceived by in vitro fertilization (IVF) compared with those conceived spontaneously.
Methods:  Data were collected from primiparous women aged 35 years and older with a singleton pregnancy conceived by IVF ( n  = 89) or spontaneously ( n  = 849). Data included antenatal data, gestational age at delivery, obstetric complications, such as pregnancy-induced hypertension, gestational diabetes, placental previa and placental abruption, mode of delivery, birth weight, fetal demise and the Apgar score at 1 min.
Results:  The elective Cesarean rate in pregnancies following IVF was significantly higher than that in the control group ( P =  0.014). However, there were no significant differences in obstetric outcomes between the two groups.
Conclusions:  The current results did not support the IVF-related risks of elderly primiparous singleton pregnancies. (Reprod Med Biol 2007; 6: 219–222)     

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.     

Second-trimester maternal serum screening for Down syndrome in in vitro fertilization pregnancies

OBJECTIVES: To examine whether second-trimester maternal serum triple marker screening results differ between in vitro fertilization (IVF) pregnancies and naturally conceived pregnancies. METHODS: Second-trimester maternal serum triple marker screening results from 88 IVF pregnancies were compared with 596 naturally conceived pregnancies (controls). Controls were matched to each IVF pregnancy by maternal age, gestational age and date of blood collection. All pregnancies in the study were known to have normal outcome. Multiple of the median (MoM) levels of human chorionic gonadotrophin (hCG), unconjugated estriol (uE3) and alpha-fetoprotein (AFP), and the false-positive rate for Down syndrome were compared between the two groups. RESULTS: No statistically significant differences in analyte levels or in Down syndrome false-positive rate were observed between the IVF and naturally conceived pregnancies. CONCLUSION: IVF patients can be counselled about maternal serum triple marker screening in the same manner as patients with naturally conceived pregnancies. There is no evidence to support the general use of analyte correction factors in the interpretation of second-trimester maternal serum screen results in IVF pregnancies.     

Risk factors for preeclampsia in Japanese twin pregnancies: comparison with those in singleton pregnancies

Objective  To identify the factors associated with the increased risk of developing preeclampsia in twin pregnancies compared with those in singleton pregnancies. Methods  We reviewed the obstetric records of all deliveries at ≥22 weeks’ gestation managed at the Japanese Red Cross Katsushika Maternity Hospital between 2001 and 2007. Results  The incidence of preeclampsia in the twin pregnancies (7.6%: 45 in 593) was significantly higher than that in the singleton pregnancies (1.7%: 196 in 11,311; P < 0.01). In singleton pregnancies, the developing preeclampsia was associated with maternal age at ≥35 years, primiparity, maternal BMI ≥25 before pregnancy, history of infertility therapies such as IVF and having a history of previous preeclampsia. In twin pregnancies, however, the developing preeclampsia was not associated with these variables. Conclusions  In Japanese women, the factors reported to be associated with the increased risk of preeclampsia in singleton pregnancies may not alter the increased risk of preeclampsia in twin pregnancies.     

Obstetric outcome after fetal reduction to singleton pregnancies

OBJECTIVE: To study the outcome after fetal reduction or selective termination to singleton pregnancies for various indications. METHODS: Fetal reduction or selective feticide to singleton pregnancies was performed in 80 multiple gestations (congenital malformations, 17 cases; high-risk obstetric conditions, 25 cases; or social/psychological indications, 38 cases). RESULTS: The overall pregnancy loss rate was 10%; however, pregnancy failure was significantly higher in selective reductions performed for preterm prelabor rupture of membranes (PPROM) (4/8) compared with monochorionic twin and bad obstetric history. Fetal reduction to singletons for psychological reasons resulted in a pregnancy wastage of 5.3% (2/38). Procedures performed at < or =14 weeks showed a significantly lower fetal loss rate (2/61; 3.3%), a higher mean gestational age at delivery (38.3+/-2.2 weeks), and a decreased prematurity rate (p< or =0.001). The number of reduced fetuses, prenatal diagnosis by chorionic villus sampling before the reduction and maternal age did not interfere with pregnancy outcome. CONCLUSION: Fetal reduction to singleton pregnancies has a favorable outcome, especially when performed before 14 weeks of gestation.     

Obstetrical outcomes of ART pregnancies in patients with male factor infertility

Purpose

Pregnancies conceived by in vitro fertilization (IVF)/intracytoplasmic sperm injection (ICSI) are associated with an increased incidence of obstetrical and neonatal complications. With the growing rate of male factor infertility, which is unique by not involving the maternal milieu, we aimed to assess whether obstetrical outcomes differed between IVF/ICSI pregnancies due to male factor infertility and those not due to male factor infertility.

Methods

A retrospective cohort study of women receiving IVF/ICSI treatments at a single hospital over a five-year period was involved in the study. Inclusion criteria were women with a viable pregnancy that delivered at the same hospital. Pregnancies were divided into male factor only related and non-male factor–related infertility. The groups were compared for several maternal and neonatal complications.

Results

In total, 225 patients met the study criteria, with 94 and 131 pregnancies belonging to the male factor and non-male factor groups, respectively. Demographic and clinical characteristics were comparable, except for younger maternal age and higher incidence of twin pregnancies in the male factor group. A sub-analysis for singleton pregnancies revealed a less likelihood of cesarean delivery, preterm birth, and male gender offspring in the male factor group (p < 0.05). These differences were not observed in the sub-analysis for twin pregnancies. Other outcome measures were similar in both groups, both for singleton and twin pregnancies.

Conclusion

Singleton IVF pregnancies due to male factor infertility are associated with a reduced incidence of some adverse outcomes, likely due to lack of underlying maternal medical conditions or laboratory conditions related to ICSI. Our findings require validation by further studies on larger samples.

     

Neonatal and obstetric outcome of pregnancies conceived by ICSI or IVF

Intracytoplasmic sperm injection (ICSI) is currently widely used despite concern regarding pregnancy complications and outcome, specifically congenital malformations. The aim of this study was to compare the obstetric and neonatal outcome of pregnancies conceived by IVF and ICSI. Long-term follow-up was achieved through questionnaires sent to women who conceived after IVF/ICSI treatment. Information was obtained regarding 219 pregnancies (322 children) conceived after ICSI and 145 pregnancies (201 children) conceived after IVF. There were no significant differences between the ICSI and regular IVF pregnancies in regard to the couple's characteristics and the obstetric complications. The mean +/- SD birth weight of the singletons conceived after ICSI was similar to that of singletons conceived after IVF: 3001 +/- 703 versus 3059 +/- 643 g respectively. In both groups there was a high incidence of multiple pregnancies, Caesarean sections, prematurity and low birth weights. The incidence of congenital malformations following IVF or ICSI pregnancies was similar, 6.3 and 7.7% respectively, but was increased compared with the general Israeli population. In summary, concern remains regarding the incidence of congenital malformations after IVF and the long-term outcome of ICSI pregnancies. However, the present results are reassuring with regard to the obstetric and neonatal outcome of pregnancies conceived by ICSI compared with those achieved by IVF.     

Effects of Asherman Syndrome on Maternal and Neonatal Morbidity with Evaluation by Conception Method

Study ObjectiveCreate a comprehensive summary of maternal and neonatal morbidities from patients previously treated for Asherman syndrome and evaluate for differences in perinatal outcomes based on conception method.DesignRetrospective cohort.SettingCommunity teaching hospital affiliated with a large academic medical center.PatientsTotal of 43 singleton births identified from 40 patients previously treated at our institution for Asherman syndrome.InterventionsReview of fertility and obstetric data to summarize the maternal and neonatal outcomes in singleton births from patients with Asherman syndrome who had been treated with hysteroscopic adhesiolysis.Measurements and Main ResultsPrimary outcomes of maternal morbidity (i.e., hypertensive disease, gestational diabetes, ruptured membranes, postpartum hemorrhage, morbidly adherent placenta [MAP]) and secondary outcomes of neonatal morbidity (i.e., gestational age at birth, method of delivery, weight, length, 1- and 5-minute Apgar score oxygen requirement, anatomic malformations, length of neonatal admission) were evaluated. We identified 40 patients who completed successful treatment of Asherman syndrome and went on to carry a singleton gestation within our institution: 20 (50%) with mild disease, 18 (45%) with moderate disease, and 2 (5%) with severe disease under the March classification system. In total, 43 singleton births were examined, with 27 of 43 (62.8%) conceived without in vitro fertilization (IVF) (group A: non-IVF conception) and 16 of 43 (37.2%) conceived through IVF (group B: IVF conception). The overall rate of preterm birth in Asherman pregnancies was 11.6%, with no difference between the 2 conception groups. We documented 9.3% cases with intrauterine growth restriction, with no difference based on conception groups. The rate of MAP in patients with Asherman syndrome was 14.0%, and the rate of postpartum hemorrhage was 32.6%, with no differences between the conception groups. Newborn anatomic malformations of any cause were documented in 18.6% of all singleton births, with no difference between the conception groups.ConclusionOur series indicates a higher incidence of intrauterine growth restriction, MAP, postpartum hemorrhage, and newborn anatomic malformations in Asherman syndrome pregnancies than that reported in pregnancies within the general population. However, we found no significant differences in the maternal and neonatal outcomes of patients with Asherman syndrome who conceived with or without IVF after being treated with hysteroscopic adhesiolysis.     

Neonatal outcome in pregnancies from ovarian stimulation

OBJECTIVE: To study the neonatal outcome in pregnancies after ovarian stimulation, not including in vitro fertilization. The outcomes studied were multiple birth, preterm birth, and low birth weight among singletons, congenital malformations, and infant death. METHODS: We identified 4029 women who delivered between 1995-1999 after ovarian stimulation alone and compared them with 438,582 women who neither had ovarian stimulation nor in vitro fertilization. We controlled for the confounding effect of year of birth, maternal age, parity, and length of subfertility before the pregnancy. RESULTS: The twinning rate was 5.9% in the study group and 1.2% in the control group. The triplet rate was 0.5% in the study group and 0.02% in the control group. A nearly doubling of the rate of monozygotic twinning was indicated in the study group compared with the control group. There was an excess of singleton preterm births and low birth weight infants in the study group, but this was mainly explainable by confounding of maternal age, parity, and subfertility. The rates of congenital malformations and perinatal deaths were increased, also mainly explainable by maternal characteristics. No increase in specific types of congenital malformations was seen. CONCLUSION: As the deviations in neonatal outcome after ovarian stimulation alone were reduced or disappeared when the confounding of maternal age, parity, and subfertility was taken into consideration, there is probably little direct effect of the stimulation procedure as such.     

Maternal smoking and gestational age in twin pregnancies

BACKGROUND: A twin pregnancy imposes greater demands on maternal physiology and smoking may thus be associated theoretically with a greater risk of preterm delivery than in singleton pregnancies. POPULATION AND METHODS: From 1989 to 1996 all women who booked for antenatal care at the Department of Gynecology and Obstetrics, Aarhus University Hospital, Denmark were asked to fill in two questionnaires. Apart from smoking habits, these questionnaires provided information on medical and obstetric history together with information on sociodemographic and other lifestyle variables. Gestational age at delivery was calculated from ultrasonographically determined fetal biparietal diameter and information about the last menstrual period. Only women carrying twins were included in the present study (n=401). RESULTS: Mean gestational age was 5 days (95% CI 1-9 days) shorter among smokers compared with non-smokers. Among non-smokers mean gestational age was 261 days (+/-18), among women who smoked 1-9 and 10+ cigarettes per day 257 days (+/-23) and 255 days (+/-20), respectively. The overall risk of preterm delivery (< 37 weeks) and delivery before 34 completed weeks was 1.3 (95% CI 0.9-2.2) and 1.4 (95% CI 0.8-2.4), respectively. Primiparous women had shorter gestational age than did multiparous women. Still, among primiparous as well as among multiparous women gestational age decreased with smoking. Adjustment for maternal age, height and prepregnancy weight, alcohol and caffeine intake, marital status, education, occupational status, preterm birth in previous pregnancies, and in vitro fertilization in the present pregnancy did not change the results. CONCLUSIONS: Smoking has a substantial effect on mean gestational age in twin pregnancies, and a dose response like relationship is present.     

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.     

Pathologic features of placentas from singleton pregnancies obtained by in vitro fertilization and embryo transfer

Fifty placentas were collected at term from singleton pregnancies resulting from in vitro fertilization (IVF) and intrauterine embryo transfer. Their pathologic features were compared with those of a control group composed of 50 placentas obtained from spontaneous singleton pregnancies. The mean maternal age, mean gestational age, mean fetal weight, sex ratio, and rate of pregnancy complications did not differ. There was also no significant difference between the groups in the mean placental weight and in the incidence of placental pathologic lesions, including extended infarcts, massive perivillous fibrin depositions, chorioangiomas, and placental inflammatory lesions. The incidence of abnormal placental shapes was significantly (P less than .05) greater in the IVF group (22%) compared with the control group (6%). A significant (P less than .025) difference was observed between the groups in the distribution of umbilical cord insertions. The mean distance between the cord insertion and the closest placental margin was significantly (P less than .005) shorter in the group conceived by IVF (3.23 +/- 1.91 cm) than in the control group (4.54 +/- 2.42 cm). A relationship between these placental morphologic features and the superficial implantation and/or inadequate orientation of the blastocyst after IVF and intrauterine embryo transfer is proposed.