Pregnancy loss rates following second trimester genetic amniocentesis

5-Year review on amniocentesis and its maternal fetal complications

Background Amniocentesis is a well-known invasive procedure which is commonly carried out in the second trimester. The indication for amniocentesis varies throughout countries and centers. Despite providing significant prenatal diagnosis; many maternal and fetal complications have been reported from previous studies. Materials and methods This retrospective study aimed to determine the maternal and fetal complications following amniocentesis. This study involved all patients who underwent amniocentesis from January 2012 until June 2017 in a tertiary centre. Maternal age, parity, premorbid medical conditions, amniocentesis indications, gestational age during amniocentesis, karyotyping results, complications during and post procedure and the fetal outcomes were reviewed and analyzed. Results One hundred and fourteen patients' medical records were reviewed and the majority of patients (50.9%) ranged in age from age 30 to 39 years old with mean age of 34.29 years. Amniocentesis was performed during the second trimester in the majority of patients (71.1%). The indications for amniocentesis in this study were polyhydramnios (7.9%), advanced maternal age (9.6%), risk of Down's syndrome (31.6%), increased risk of Patau syndrome (6.1%), increased risk of Edward's syndrome (4.4%) and abnormal fetal ultrasonography (70.2%). Cytogenetics results of amniocentesis were normal in 82 patients (71.9%). The majority of patients (86.0%) had no complications. Two patients (12.5%) had intrauterine death presumed to be procedural related. Conclusion This 5-year retrospective study on amniocentesis procedure showed that the majority of amniocentesis were safe as 86.0% of the patients were free from any complications. Anticipating its complication is important as there is always a risk even though it is a safe procedure in general.

Single or double needle insertion in twin's amniocentesis: Does the technique influence the risk of complications?

OBJECTIVE

To compare complication rates following amniocentesis in twin gestations, according to sampling technique and number of needle insertions.

STUDY DESIGN

A retrospective cohort study of all women with twin gestations who underwent amniocentesis and delivered in a single university affiliated medical center during 2002-2016. Amniocentesis was performed either through one uterine entry with passage through the inter-twin membrane or through two different entries to the two amniotic sacs. Pregnancy outcome of women that underwent single needle insertion amniocentesis, was compared to this of double needle insertion. Primary outcome was neonatal complications within 4 weeks after amniocentesis (late abortion, chorioamnionitis, preterm premature rupture of membranes, or hospitalization due to related symptoms). Secondary outcomes were gestational week at delivery and labor characteristics.

RESULTS

The study group comprised 212 women. Of them, 73 (34.4%) underwent a single uterine insertion and 139 (65.6%) two separate needle insertions. Baseline characteristics did not differ between the groups. The amniocentesis complication rate was 13.7% in the single insertion group and 16.5% in the double insertion group (p = 0.587). Multivariate analysis found that a single insertion method had no statistically significant influence on complication rate, after making adjustments for potential confounders (OR = 1.085, 95% CI 0.4-2.9; p = 0.871). Other labor characteristics were similar between the groups.

CONCLUSION

Needle insertion technique in twin gestation amniocentesis was not associated with procedure related complications.

Comparison of adverse perinatal outcomes after single-needle and double-needle CVS techniques

OBJECTIVE

To determine the impact of the chorion villus sampling (CVS) technique on adverse perinatal outcomes.

METHODS

In this case-control study, 412 women who underwent CVS at 11-14 weeks of gestation and 231 women who did not undergo any invasive procedure were retrospectively evaluated. The women in the CVS group were further divided into two groups according to the use of single-needle technique (n=148) vs. double-needle technique (n=264). The adverse outcomes were compared between controls and the two CVS groups, and regression analysis was used to determine the significance of independent contribution.

RESULTS

The rate of preeclampsia for the control group was 2.2%, for the double-needle group was 3% and for the single-needle group was 8.1%. CVS with single-needle technique was found to be an independent and statistically significant risk factor for preeclampsia [odds ratio (OR)=2.1, 95% confidence interval (CI); 1.4-2.7, P=0.008].

CONCLUSION

The risk of preeclampsia after CVS appears to be increased with single-needle technique compared with double-needle technique.

Prenatal screening for Down syndrome in Australia: costs and benefits of current and novel screening strategies

OBJECTIVE

To analyse the cost-effectiveness and performance of noninvasive prenatal testing (NIPT) for high-risk pregnancies following first-trimester screening compared with current practice.

METHODS

A decision tree analysis was used to compare the costs and benefits of current practice of first-trimester screening with a testing pathway incorporating NIPT. We applied the model to 32 478 singleton pregnancies screened between January 2005 and December 2006, adding Medicare rebate data as a measure of public health system costs. The analyses reflect the actual uptake of screening and diagnostic testing and pregnancy outcomes in this cohort.

RESULTS

The introduction of NIPT would reduce the number of invasive diagnostic procedures and procedure-related fetal losses in high-risk women by 88%. If NIPT was adopted by all women identified as high risk by first-trimester combined screening, up to 7 additional Down syndrome fetuses could be confirmed. The cost per trisomy 21 case confirmed, including NIPT was 9.7% higher ($56,360) than the current prenatal testing strategy ($51,372) at a total cost of $3.91 million compared with $3.57 million over 2 years.

CONCLUSION

Based on the uptake of screening and diagnostic testing in a retrospective cohort of first-trimester screening in Western Australia, the implementation of NIPT would reduce the number of invasive diagnostic tests and the number of procedure-related fetal losses and increase the cost by 9.7% over two years. Policy planning and guidelines are urgently required to manage the funding and demand for NIPT services in Australia.

Pregnancy loss after chorionic villus sampling and genetic amniocentesis in twin pregnancies: a systematic review

OBJECTIVE

To review the available evidence regarding pregnancy loss following first-trimester chorionic villus sampling (CVS) and mid-trimester genetic amniocentesis in twins.

METHODS

We searched the MEDLINE database from January 1990 to May 2011 for randomized and cohort studies reporting on the risk of pregnancy loss after first-trimester CVS performed between 9 and 14 weeks and after genetic amniocentesis performed between 14 and 22 weeks. Where appropriate, we calculated pooled proportions and relative risks with 95% CI.

RESULTS

No randomized studies were found. For CVS, nine studies fulfilled the inclusion criteria. The overall pregnancy-loss rate was 3.84% (95% CI, 2.48-5.47; n = 4). The rate of pregnancy loss before 20 weeks was 2.75% (95% CI, 1.28-4.75; n = 3) and before 28 weeks was 3.44% (95% CI, 1.67-5.81; n = 3). For amniocentesis, the overall pregnancy-loss rate was 3.07% (95% CI, 1.83-4.61; n = 4). The rate of pregnancy loss before 20 weeks was 2.25% (95% CI, 1.23-3.57; n = 2), before 24 weeks was 2.54% (95% CI, 1.43-3.96; n = 9) and before 28 weeks was 1.70% (95% CI, 0.37-3.97; n = 5). Pooled data from four case-control studies showed a higher risk (2.59% vs. 1.53%) of pregnancy loss before 24 weeks following amniocentesis (relative risk = 1.81; 95% CI, 1.02-3.19). There were no statistically significant differences in reported pregnancy loss between transabdominal and transcervical approaches, use of a single-needle system vs. a double-needle system and single uterine entry vs. double uterine entry in the CVS group. Similarly, in the amniocentesis group, there was no statistically significant difference in fetal loss between the single uterine entry vs. the double uterine entry.

CONCLUSION

In the absence of randomized studies, it is not possible to estimate accurately the excess risk following invasive procedures in twins. Currently available data show similar overall pregnancy-loss rates for both amniocentesis and CVS with the excess risk of around 1% above the background risk.

Amniocentesis in twin pregnancies: a systematic review of the literature

OBJECTIVE

Using published data, we sought to determine the amniocentesis-related loss rate in twin gestations.

METHODS

We searched the PUBMED database using keywords "amniocentesis", "twin" and "twins" to identify articles evaluating genetic amniocentesis in twin gestations published from January 1970 to December 2010. Random effects models were used to pool procedure-related loss rates from included studies.

RESULTS

The definition of "loss" varied across the 17 studies identified (Table 1). The pooled procedure-related loss rate at < 24 weeks was 3.5% (95% confidence interval [CI] 2.6-4.7) (Figure 2). Pooled loss rates at < 28 weeks (Figure 4) and to term (Figure 5) could not be calculated due to unacceptable heterogeneity of available data. Seven studies included a control (no amniocentesis) group and reported a pooled odds ratio for total pregnancy loss among cases of 1.8 (95% CI 1.2-2.7) (Figure 3). Only 1 study reported procedure-related loss rates by chorionicity (7.7% among monochorionics vs 1.4% among controls; p 0.02).

CONCLUSION

Analysis of published data demonstrated a pooled amniocentesis-related loss rate of 3.5% in twin gestations < 24 weeks. Pooled loss rates within other post-amniocentesis intervals or other gestational age windows and the impact of chorionicity on procedure-related loss rates cannot be determined from published data.

Mid-Trimester Amniocentesis Fetal Loss Rate

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Risk factors for procedure-related fetal losses after mid-trimester genetic amniocentesis

BACKGROUND

The objective of this study was to determine the institutional pregnancy loss rate following second-trimester genetic amniocentesis and to ascertain whether factors exist which would identify pregnancies at increased risk of having a procedure-related fetal loss.

SETTING

University Teaching Hospital

METHODS

Details of the procedure and pregnancy outcome of all patients who had amniocentesis planned or performed between 15-22 gestational weeks between January 1997 and June 2004 were extracted from our clinical audit database. The procedure-related fetal loss rate, defined as all unintended abortions, stillbirths and neonatal deaths without major fetal abnormalities or obvious obstetric causes, was determined and compared to a presumed background fetal loss rate of 0.8% based on a cohort of women who did not undergo the procedure.

RESULTS

A total of 3468 consecutive amniocentesis were performed in 3440 patients with 3498 fetuses. The mean gestational age at amniocentesis was 17.6 +/- 1.2 weeks. The majority (98.6%) required only one puncture and a transplacental procedure was required in 2.7% cases. A total of 3465 chromosomal studies were performed. Sixty six cases (1.9%) of major chromosomal abnormalities were detected. Pregnancy outcome was ascertained in all except 26 singleton pregnancies (0.74%). There were 3285 (93.9%) livebirths, 103 (2.9%) termination of pregnancies (TOP), 6 (0.17%) fetal demises before the procedure, and 20 (0.61%) unintended fetal losses due to significant fetal abnormalities or obstetric complications. The remaining 58 fetal losses (1.66%) were classified as potentially procedure-related, which could be either background fetal losses or procedure-related. The procedure-related fetal loss rate after correcting for the background loss rate was 0.86%.Potentially procedure-related fetal losses were found to be significantly associated with a procedure at 18 weeks or beyond (odds ratio OR = 1.97), a procedure performed for abnormal second-trimester biochemical screening test (OR = 3.08), a bloody tap (OR = 6.48), and a female fetus (OR = 2.39); but not to the number of punctures (p = 0.66) nor transplacental amniocentesis (p = 0.104).

CONCLUSIONS

Mid-trimester amniocentesis is associated with a small but significant risk of fetal loss of 0.86%.

Diagnostic mid trimester amniocentesis: how safe?

OBJECTIVE

Genetic mid-trimester amniocentesis is a common invasive procedure. The origin of the commonly quoted 0.5% rate of procedure-related pregnancy loss after amniocentesis is obscure and is in conflict with the only randomized prospective study that reported a procedure-related rate of loss of 1.0%. This review was performed to establish an estimate of procedure-related pregnancy loss after mid-trimester amniocentesis. The impact of placental puncture on the rate of loss and the risk of direct needle injury to the fetus were also examined.

STUDY DESIGN

The National Library of Medicine database was used to identify English language reports of >1000 amniocenteses with sufficient detail and follow up data to allow the calculation of the rate of spontaneous pregnancy loss after amniocentesis but before 28 completed weeks. These reports were divided into 2 groups to assess the impact of the ultrasound technique. Group I described only preamniocentesis ultrasound evaluation; group II described primarily concurrent ultrasound needle guidance. Pregnancy loss between the 2 groups was compared. The impact of placental puncture and reported direct fetal trauma were examined. The significance of differences was tested using chi-square analysis, with significance at a probability value of < or =.05.

RESULTS

Twenty-nine reports that totaled 68,119 amniocenteses were examined. In a comparison of all studies in group I with all studies in group II, there was a lower rate of loss after amniocenteses with the use of concurrent guidance (1.4%) compared with the use of preamniocentesis ultrasound evaluation (2.1%) that was significant ( P <.001). Among only the 5 controlled studies that used preamniocentesis ultrasound evaluation, the difference in rate of loss between amniocentesis patients and control subjects was 0.6% ( P =.0042; 95% CI, 0.19, 1.03), which was identical to the difference in the rate of loss of 0.6% between amniocentesis patients and control subjects from the 5 controlled studies that used concurrent ultrasound needle guidance ( P <.0001; 95% CI, 0.31, 0.90). Multiple case reports and small series of presumed fetal needle trauma were reviewed, but most of these attributed causation to the amniocentesis needle based only on circumstantial association. Two cases with direct evidence of fetal needle trauma are discussed. Finally, the rate of loss after placental puncture from among 9 reports that provided this detail was 1.4% and not different from the overall rate of loss that was noted in group II.

CONCLUSION

This examination of experience with 68,119 amniocenteses from both controlled and uncontrolled studies provides a substantive basis for several conclusions: (1) Contemporary amniocentesis with concurrent ultrasound guidance in controlled studies appears to be associated with a procedure-related rate of excess pregnancy loss of 0.6% (95% CI, 0.31, 0.90). To determine the total rate of loss, this must be added to the reported natural rate of loss without amniocentesis among control patients of 1.08%. (2) The use of concurrent ultrasound guidance appears to reduce the number of punctures and the incidence of bloody fluid. Concurrent ultrasound guidance was associated with a reduced rate of loss when all studies were compared, but not among controlled studies. (3) Direct fetal needle trauma is rare, and rarely proved, but may occur more frequently than is reported because of a failure to diagnose and a failure of the consistent production of sequelae. (4) This experience does not substantiate an increased rate of pregnancy loss if placental puncture is required.

Second-trimester genetic amniocentesis: 5-year experience

AIMS

The purpose of this study is to evaluate the data related to the genetic amniocentesis performed in a single university hospital.

METHODS

Medical records were used to analyze indications of amniocentesis, the results of chromosome analysis, complications and pregnancy outcomes from January 1998 through January 2002. Anomaly screening was performed to all patients attending to our Obstetrics and Gynecology Department between 16 and 20 weeks of pregnancy. The staff obstetricians-gynecologists performed all of the second-trimester genetic amniocentesis.

RESULTS

Totally 2,686 patients attended to our department between 16 and 20 weeks of pregnancy during the index period. A total of 131 genetic amniocentesis were performed. The indications were advanced maternal age (cut off age 35) in 24, suspicion of genetic abnormality on ultrasound in 15, history of siblings with Down syndrome in 2 and abnormal triple screen in 90 patients, respectively. There were two pregnancy losses due to the procedure; thus the overall complication rate of second-trimester genetic amniocentesis was 1.5%.

CONCLUSIONS

Being one of the most performed invasive techniques for prenatal diagnose, second-trimester genetic amniocentesis is a reliable and safe method. Although the size of this study is limited, our complication rates are similar to the related literature.

Second-trimester amniocentesis vs. chorionic villus sampling for prenatal diagnosis in multiple gestations

OBJECTIVE

To study the impact of invasive procedures for prenatal diagnosis on multiple pregnancies and compare first-trimester chorionic villus sampling with second-trimester amniocentesis.

DESIGN

Retrospective study of 347 second-trimester amniocenteses and 69 chorionic villus sampling procedures.

RESULTS

Miscarriage occurred in 4.18% of women after amniocentesis and 4.54% of women after chorionic villus sampling. In the amniocentesis group the risk of miscarriage was higher in the cases with transplacental entry (4.54%) than in those with transamniotic entry (2.08%). The rates of preterm delivery < or = 32 weeks and preterm delivery < or = 35 weeks in the amniocentesis group were 11.8% and 32.4% and in the chorionic villus sampling group 16.66% and 23.8%, respectively. Total fetal loss rate was similar in the amniocentesis group (8.8%) and the chorionic villus sampling group (10.22%). In the 21 cases where selective feticide was carried out the total fetal loss rate was lower in the chorionic villus sampling group (8.3%) than in the amniocentesis group (11.1%), although the difference did not reach statistical significance.

CONCLUSION

Chorionic villus sampling appears to be a safe alternative to amniocentesis and should be considered as the method of choice particularly when there is a high risk of an affected fetus necessitating selective feticide.

Elevated monocyte chemotactic protein-1 in amniotic fluid is a risk factor for pregnancy loss

OBJECTIVE

Pregnancy loss after mid-trimester amniocentesis occurs in 0.5-1% of cases and is frequently attributed to the procedure. Accumulating evidence implicates a pre-existing, but clinically silent, intra-amniotic inflammation in the etiology of adverse pregnancy outcome after mid-trimester amniocentesis. Monocyte chemotactic protein-1 (MCP-1) is a potent chemokine produced by a wide variety of cells during the course of an inflammatory response. This study was designed to assess if the amniotic fluid concentration of this chemokine identifies patients at risk for spontaneous abortion and/or fetal death.

METHOD

A retrospective case-control study of women who had a mid-trimester amniocentesis was designed. Cases (n = 10) consisted of patients who had a spontaneous pregnancy loss after the procedure, while the control group (n = 84) consisted of patients who had a normal pregnancy outcome after mid-trimester amniocentesis. MCP-1 was measured by a specific enzyme immunoassay (sensitivity, 18.3 pg/ml). The Kolmogorov-Smirnov test was utilized to assess normal distribution of the data. Logarithmic transformation was applied to achieve normality. Statistical analysis was performed using Student's t test. A receiver operating characteristic (ROC) curve analysis was used to select a cut-off to dichotomize amniotic fluid concentrations of MCP-1.

RESULTS

MCP-1 was detectable in all amniotic fluid samples. Patients who had a mid-trimester amniocentesis and a subsequent pregnancy loss had a higher mean amniotic fluid log MCP-1 concentration than those with a normal pregnancy outcome (pregnancy loss, mean 2.95 +/- 0.19 pg/ml vs. normal outcome, mean 2.78 +/- 0.19 pg/ml; p = 0.01). A cut-off of > 765 pg/ml was selected by ROC curve analysis (area under the curve, 0.74; p = 0.01). An amniotic fluid concentration of MCP-1 above this level was strongly associated with pregnancy loss (odds ratio, 7.35; 95% confidence interval, 1.7-31.1), a sensitivity of 70%, and a specificity of 76%.

CONCLUSION

A subset of women who had a pregnancy loss after a mid-trimester amniocentesis had higher concentrations of the chemokine MCP-1 than those who had a normal pregnancy outcome. Subclinical intra-amniotic inflammation is a risk factor for pregnancy loss after mid-trimester amniocentesis. This observation may have medicolegal and clinical implications. An elevated MCP-1 concentration in amniotic fluid of patients with a pregnancy loss after a mid-trimester amniocentesis indicates that a pathological condition was present at the time of the procedure.

Leiomyomata uteri, genetic amniocentesis, and the risk of second-trimester spontaneous abortion

OBJECTIVE

The purpose of this study was to determine the impact of leiomyomata uteri on the risk of second-trimester spontaneous abortion and to determine whether genetic amniocentesis further increases this risk.

STUDY DESIGN

We retrospectively identified pregnant women with leiomyomata uteri who underwent genetic amniocentesis (cases) at the University of Rochester and the Johns Hopkins Hospital between April 1994 and June 2000. Two control groups were also identified: (1) pregnant women without leiomyomata who had undergone genetic amniocentesis (amnio only) and (2) pregnant women at similar gestational ages with leiomyomata who had not undergone amniocentesis (myoma only). Cases and controls were matched for maternal age and parity. All subjects were then followed up to ascertain pregnancy outcomes.

RESULTS

One hundred twenty-eight women with leiomyomata uteri who underwent genetic amniocentesis were identified and matched with 128 amnio-only controls and 128 myoma-only controls. The incidence of spontaneous abortion was 6.3% among the cases, 0.8% in the amnio-only controls, and 7.0% in the myoma-only controls. The relative risk (95% CI) for spontaneous abortion was 8.0 (1.02-63.04) for cases versus amnio only but was not significantly different from 1.0 for cases versus myoma-only controls.

CONCLUSIONS

Women with leiomyomata are at an increased risk for second-trimester spontaneous abortion. Midtrimester amniocentesis does not appear to further increase this risk.

Teaching ultrasound-guided invasive procedures in fetal medicine: learning curves with and without an electronic guidance system

OBJECTIVE

To compare the learning curves of inexperienced junior obstetrics/gynecology registrars for ultrasound-guided invasive procedures on a training model, with and without an electronic guidance system.

STUDY DESIGN

Four junior registrars performed their first 100 procedures on a training model with a new electronic guidance system, and four other junior registrars performed their first 100 procedures on the same training model without using the guidance system. All procedures were performed using a free-hand technique. We evaluated the quality of the procedure, which we defined as the time spent with the entire needle clearly visualized on the screen over the total duration of the procedure. We constructed learning curves for the eight junior registrars for comparative analysis.

RESULTS

Quality of the procedure increased over time for all trainees. The learning curves were significantly steeper for trainees using the electronic guidance system. Trainees using the electronic guidance system performed better in the middle of their learning curve (procedures 25-75). All trainees reached the same level of quality by the end of their 100 procedures.

CONCLUSIONS

The automated electronic guidance system helps faster learning but, after 100 procedures on a training model, both groups reached the same level of quality.

A randomised trial of progesterone prophylaxis after midtrimester amniocentesis

BACKGROUND

Midtrimester amniocentesis to investigate fetal karyotype carries a small risk of fetal loss.

AIM

To test the hypothesis that progesterone prophylaxis may reduce this.

STUDY DESIGN

A randomised controlled trial comparing a short prophylactic treatment with progesterone after amniocentesis with untreated controls.

RESULTS

There were no differences in frequency of miscarriage, preterm delivery or neonatal outcome.

CONCLUSION

Prophylactic progesterone treatment after amniocentesis does not improve obstetric outcome.

Genetic sonography: a cost-effective method for evaluating women 35 years and older who decline genetic amniocentesis

OBJECTIVE

To determine whether offering genetic sonography to patients who decline invasive testing can increase the detection rate of trisomy 21 and is cost-effective.

METHODS

The detection rate of trisomy 21, the number of pregnancy losses after amniocentesis, and the cost of detecting a single fetus with trisomy 21 were determined in women 35 years and older managed according to the following 3 policies: (1) universal amniocentesis, (2) genetic counseling for maternal age-associated risks for trisomy 21 followed by amniocentesis in patients who elected it, and (3) genetic counseling followed by genetic sonography in patients who originally declined genetic amniocentesis.

RESULT

From a population of 40,143 women 35 years and older, the expected number of trisomy 21 fetuses was 349. After genetic counseling, 32% of patients declined invasive testing, resulting in detection of 70% of fetuses with trisomy 21. For universal amniocentesis, the cost to detect 1 fetus with trisomy 21 was $138,036. For the 32% who declined invasive testing after genetic counseling and underwent genetic sonography, the cost to detect a single fetus with trisomy 21 was a function of sensitivity and the screen-positive rate. For screen-positive rates between 5% and 25%, genetic sonography resulted in a cost savings between 14.3% and 18.8% when compared with universal invasive testing and resulted in a considerable increase in detection of fetuses with trisomy 21 (77% to 97%).

CONCLUSIONS

A policy of offering genetic sonography followed by amniocentesis to patients 35 years and older who originally decline invasive testing for the diagnosis of trisomy 21 is cost-effective and results in a higher overall detection rate for trisomy 21 without an increased risk of pregnancy loss.

Repeated ultrasound guided fetal injections of corticosteroid alter nervous system maturation in the ovine fetus

INTRODUCTION

Recent studies in sheep have shown that repeated maternal injections of betamethasone are associated with adverse effects within the nervous system. Repeated fetal injections of betamethasone achieve serial improvements in preterm lung function in sheep and are a possible alternative to repeated maternal therapy. We have evaluated the effect of repeated fetal administration of betamethasone on nervous system maturation in an ovine model.

METHODS

Date-mated ewes (n = 48) were randomized to receive ultrasound-guided fetal injections of betamethasone or saline between days 104 to 124 of gestation and were delivered by cesarean section on day 125 or 145 (term = 150). Optic and sciatic nerves were prepared for light and electronmicroscopy. Eye diameters were measured and transverse sections of retinae were evaluated. Data were analyzed using a mixed model analysis of variance.

RESULTS

Repeated fetal administration of corticosteroid did not significantly affect optic nerve myelination but resulted in significant delays in sciatic axonal growth (p < 0.02) and retinal maturation (p < 0.04). The process of performing repeated fetal injections also significantly affected some retinal parameters.

CONCLUSION

Repeated fetal administration of betamethasone alters some aspects of nervous system maturation in sheep. It is premature to plan trials of repeated fetal corticosteroid therapy in humans.