Complication rate after termination of pregnancy for fetal defects.

OBJECTIVES: To assess the risk of complications in women undergoing termination of pregnancy (TOP) for fetal defects and to examine the impact of gestational age on the complication rate. METHODS: This was a retrospective study of women with a singleton pregnancy undergoing TOP at the University Hospital of Tübingen, Germany, between 2018 and 2021. TOP was performed by experienced operators according to the national protocol; dilatation and curettage (D&C) or evacuation (D&E) was used in the first and early second trimesters and induction was used later in pregnancy. The following were considered to be significant procedure-related complications: blood loss of more than 500 mL, uterine perforation, need for blood transfusion, allergic reaction, creation of a false passage (via falsa), systemic infection, readmission to hospital, any unplanned surgical procedure, such as repeat D&C/D&E or hysterectomy, and maternal death. RESULTS: The search of the hospital database identified 416 pregnancies that met the study criteria. Median maternal and gestational age at termination were 34.1 years and 17.4 weeks, respectively. In the first, second and third trimesters, respectively, 84 (20.2%), 278 (66.8%) and 54 (13.0%) pregnancies were terminated, for which D&C or D&E was used in 80 (95.2%), 21 (7.6%) and 0 (0.0%) cases. Seventy-seven (18.5%) women had at least one previous Cesarean section and 169 (40.6%) had at least one previous spontaneous delivery. Overall, 95 (22.8%) women had complications during or after TOP. A significantly higher complication rate was noted for terminations performed later in pregnancy. The median gestational age at termination was 16.6 weeks in women who did not experience complications and 20.7 weeks in those with complications (P < 0.001). The respective complication rates in the first, second and third trimesters were 6.0%, 27.0% and 27.8%. CONCLUSION: In women undergoing TOP for fetal defects, the risk of complications increases with advancing gestational age. © 2023 The Authors. Ultrasound in Obstetrics & Gynecology published by John Wiley & Sons Ltd on behalf of International Society of Ultrasound in Obstetrics and Gynecology.

Risk of fetal loss after chorionic villus sampling in twin pregnancy derived from propensity score matching analysis.

OBJECTIVE: To estimate the risk of fetal loss associated with chorionic villus sampling (CVS) in twin pregnancy, using propensity score analysis. METHODS: This was a multicenter cohort study of women with twin pregnancy undergoing ultrasound examination at 11-13 weeks' gestation, performed in eight fetal medicine units in which the leadership were trained at the Harris Birthright Research Centre for Fetal Medicine in London, UK, and in which the protocols for screening, invasive testing and pregnancy management are similar. The risk of death of at least one fetus was compared between pregnancies that had and those that did not have CVS, after propensity score matching (1:1 ratio). This procedure created two comparable groups by balancing the maternal and pregnancy characteristics that lead to CVS being performed, similar to how randomization operates in a randomized clinical trial. RESULTS: The study population of 8581 twin pregnancies included 445 that had CVS. Death of one or two fetuses at any stage during pregnancy occurred in 11.5% (51/445) of pregnancies in the CVS group and in 6.3% (515/8136) in the non-CVS group (P < 0.001). The propensity score algorithm matched 258 cases that had CVS with 258 non-CVS cases; there was at least one fetal loss in 29 (11.2%) cases in the CVS group and in 35 (13.6%) cases in the matched non-CVS group (odds ratio (OR), 0.81; 95% CI, 0.48-1.35; P = 0.415). However, there was a significant interaction between the risk of fetal loss after CVS and the background risk of fetal loss; when the background risk was higher, the risk of fetal loss after CVS decreased (OR, 0.46; 95% CI, 0.23-0.90), while, in pregnancies with a lower background risk of fetal loss, the risk of fetal loss after CVS increased (OR, 2.45; 95% CI, 0.95-7.13). The effects were statistically significantly different (P-value of the interaction = 0.005). For a pregnancy in which the background risk of fetal loss was about 6% (the same as in our non-CVS population), there was no change in the risk of fetal loss after CVS, but, when the background risk was more than 6%, the posterior risk was paradoxically reduced, and when the background risk was less than 6%, the posterior risk increased exponentially; for example, if the background risk of fetal loss was 2.0%, the relative risk was 2.8 and the posterior risk was 5.6%. CONCLUSION: In twin pregnancy, after accounting for the risk factors that lead to both CVS and spontaneous fetal loss and confining the analysis to pregnancies at lower prior risk, CVS seems to increase the risk of fetal loss by about 3.5% above the patient's background risk. © 2021 International Society of Ultrasound in Obstetrics and Gynecology.

Fetal loss after chorionic villus sampling in twin pregnancy.

OBJECTIVE: To estimate the chorionic villus sampling (CVS)-related risk of fetal loss in twin pregnancy after adjustment for chorionicity, nuchal translucency thickness (NT), intertwin discordance in crown-rump length (CRL), maternal demographic characteristics and serum pregnancy-associated plasma protein-A (PAPP-A) and free ß-human chorionic gonadotropin (ß-hCG). METHODS: This was a multicenter study from eight fetal medicine units in which the leadership were trained at the Harris Birthright Research Centre for Fetal Medicine in London, UK, and in which the protocols for screening, invasive testing and pregnancy management are similar. Data were obtained prospectively from women with twin pregnancy undergoing routine ultrasound examination at 11-13 weeks' gestation. Multivariable logistic regression analysis with backward stepwise elimination was used to examine whether CVS provided a significant independent contribution to the prediction of risk of fetal loss after adjusting for maternal and pregnancy characteristics, including maternal age, racial origin and weight, method of conception, smoking status, parity, chorionicity, intertwin discordance in CRL, fetal NT ≥ 95th percentile and free ß-hCG and PAPP-A multiples of the median. Similarly, within the CVS group, multivariable logistic regression analysis was used to investigate the effect of the number of intrauterine needle insertions and size of the needle on the risk of fetal loss. RESULTS: The study population of 8581 twin pregnancies undergoing ultrasound examination at 11-13 weeks' gestation included 316 dichorionic and 129 monochorionic twins that had CVS. First, in twin pregnancies undergoing CVS, compared to those not undergoing CVS, there was a 2-fold increased risk of fetal loss at < 24 weeks' gestation and of loss at any stage in pregnancy. Second, the factors providing a significant independent contribution to the prediction of miscarriage or fetal loss in twin pregnancy were increased maternal weight, black racial origin, monochorionicity, and more so monoamnionicity, large intertwin discordance in CRL and increased fetal NT, and, in the case of fetal loss at any stage, there was also a contribution from assisted conception and low serum PAPP-A. Third, after adjustment for maternal and pregnancy characteristics, CVS did not provide a significant contribution to the risk of fetal loss. Fourth, in twin pregnancies that had CVS, there was no significant contribution to fetal loss from the number of intrauterine needle insertions or needle size. CONCLUSION: The 2-fold increased risk of fetal loss following CVS in twin pregnancy can, to a great extent, be explained by maternal and pregnancy characteristics rather than the invasive procedure itself. © 2021 International Society of Ultrasound in Obstetrics and Gynecology.

Outcome of pregnancies with recent primary cytomegalovirus infection in first trimester treated with hyperimmunoglobulin: observational study.

OBJECTIVE: To examine the efficacy of hyperimmunoglobulin (HIG) treatment in women with a recent primary cytomegalovirus (CMV) infection up to 14 weeks' gestation. METHODS: This is an ongoing observational study conducted at the prenatal medicine departments of the University Hospitals of Tübingen, Bonn, Cologne and Erlangen, Germany, as well as at the Laboratory Prof. Gisela Enders and Colleagues in Stuttgart, Germany and the Institute for Medical Virology at the University of Tübingen, Tübingen, Germany. Enrolment criteria were the presence of confirmed recent primary CMV infection in the first trimester and a gestational age at first HIG administration of ≤ 14 weeks. The following inclusion criteria indicated a recent primary infection: low anti-immunoglobulin (Ig)-G levels, low anti-CMV-IgG avidity in the presence of a positive CMV-IgM test and no positive reactivity or just seroconversion anti-gB2-IgG-reactivity. HIG administration was started as soon as possible within a few days after the first visit. HIG was administered intravenously at a dose of 200 IU/kg maternal body weight and repeated every 2 weeks until about 18 weeks' gestation. The primary outcome was maternal-fetal transmission at the time of amniocentesis. Multivariate logistic regression analysis was used to determine significant covariates that could predict maternal-fetal transmission. RESULTS: We included 149 pregnancies (153 fetuses) that completed the treatment. Median maternal age and weight were 32.0 years and 65.0 kg, respectively. Median gestational age at the time of first referral to one of the four centers was 9.4 weeks. Median anti-CMV-IgG level, anti-CMV-IgM index and CMV-IgG avidity were 5.7 U/mL, 2.5 and 22.3%, respectively. HIG treatment was started at a median gestational age of 10.6 weeks and ended at a median of 17.9 weeks. Within this time frame, HIG was administered on average four times in each patient. Amniocentesis was carried out at a median gestational age of 20.4 weeks. In 143 (93.5%) of the 153 cases, the fetus was not infected. Maternal-fetal transmission occurred in 10 cases (6.5% (95% CI, 3.2-11.7%)). On uni- and multivariate logistic regression analysis, the level of anti-IgM index was the only factor associated significantly with maternal-fetal transmission at amniocentesis. However, only four (40.0%) of the 10 cases with maternal-fetal transmission had an anti-IgM index above 11.4, which corresponds to the 95th centile of pregnancies without transmission. CONCLUSIONS: HIG is a treatment option to prevent maternal-fetal transmission in pregnancy with a primary CMV infection. However, HIG treatment seems to be beneficial primarily in women with a recent primary infection in the first trimester or during the periconceptional period, and when it is administered at a biweekly dose of 200 IU/kg. © 2021 The Authors. Ultrasound in Obstetrics & Gynecology published by John Wiley & Sons Ltd on behalf of International Society of Ultrasound in Obstetrics and Gynecology.

Single and repeat cervical-length measurement in twin gestation with threatened preterm labor.

OBJECTIVE: To examine the effectiveness of single and repeat sonographic cervical-length (CL) measurement in predicting preterm delivery in symptomatic women with a twin pregnancy. METHODS: This was a retrospective study of women with a twin gestation who presented with painful and regular uterine contractions at 24 + 0 to 33 + 6 weeks' gestation at the perinatal unit of the University Hospital of Tübingen, Tübingen, Germany between 2012 and 2018. CL was measured on transvaginal ultrasound at the time of admission and a few days later after cessation of contractions. Treatment included administration of tocolytics (usually oral nifedipine), for no more than 48 h, and administration of steroids if CL was ≤ 25 mm. Patients were clustered into five groups according to the CL measurement obtained at first assessment: < 10.0 mm; between 10.0 and 14.9 mm; between 15.0 and 19.9 mm; between 20.0 and 24.9 mm; and ≥ 25.0 mm. For each group, we calculated the test performance of CL measurement for prediction of preterm delivery within the subsequent 7 days and before 34 weeks' gestation. Regression analysis was used to evaluate the test performance of the second CL measurement for predicting preterm delivery within 7 days after the second assessment. RESULTS: The study population consisted of 257 twin pregnancies, of which 80.2% were dichorionic diamniotic. Median maternal and gestational ages at the time of admission were 32.0 years and 29.9 weeks' gestation, respectively. Preterm birth within 7 days of admission occurred in 23 (8.9%) pregnancies, and 82 (31.9%) patients delivered prior to 34 weeks' gestation. Median CL for the entire study population was 17.0 mm. Delivery within 7 days after the first assessment occurred in 29.0%, 10.6%, 4.2%, 6.3% and 0% of women with CL < 10.0 mm, 10.0-14.9 mm, 15.0-19.9 mm, 20.0-24.9 mm and ≥ 25.0 mm, respectively. There was a weak, but significant, association between the CL measurement at the time of admission and the time interval between admission and delivery (interval = 27.9 + 0.58 × CL; P = 0.003, r = 0.184). CL was measured again after a median time interval of 3 (interquartile range (IQR), 2-5) days in 248 cases. Median second CL measurement was 17.0 (IQR, 11.5-22.0) mm. Delivery occurred within the subsequent 7 days after the second measurement in 25/248 (10.1%) cases. Binary regression analysis indicated that the first (odds ratio (OR), 0.895; P = 0.003) and second (OR, 0.908; P = 0.002) CL measurements, but not the difference between the two measurements (OR, 0.961; P = 0.361), were associated significantly with delivery within 7 days after the second measurement. Receiver-operating-characteristics (ROC)-curve analysis for the prediction of delivery within 7 days after the second assessment did not show a significant difference between the predictive performance of the first (area under ROC curve (AUC), 0.676 (95% CI, 0.559-0.793)) and the second (AUC, 0.661 (95% CI, 0.531-0.790)) measurement. CONCLUSION: Sonographic measurement of CL can be helpful in predicting preterm delivery within 7 days of presentation in symptomatic women with a twin gestation; however, the test performance is relatively weak. Copyright © 2019 ISUOG. Published by John Wiley & Sons Ltd.

Prevention of maternal-fetal transmission of cytomegalovirus after primary maternal infection in the first trimester by biweekly hyperimmunoglobulin administration.

OBJECTIVE: To examine the efficacy of biweekly hyperimmunoglobulin (HIG) administration to prevent maternal-fetal transmission of cytomegalovirus (CMV) in women with primary first-trimester CMV infection. METHODS: This was a prospective observational study of women with confirmed primary CMV infection in the first trimester who had the first HIG administration at or before 14 weeks' gestation. All women had biweekly HIG treatment until 20 weeks' gestation at a dose of 200 IU/kg of maternal body weight. Each subject underwent amniocentesis at least 6 weeks after first presentation at about 20 weeks. Primary outcome was maternal-fetal transmission at the time of amniocentesis, and secondary outcome was the frequency of congenital CMV infection at birth. The results were compared with a historic cohort of women with first-trimester CMV infection who did not undergo HIG treatment and who had amniocentesis at about 20 weeks. RESULTS: Subjects were 40 pregnant women with a primary CMV infection, with a median gestational age at first presentation of 9.6 (range, 5.1-14.3) weeks. On average, HIG administration started at 11.1 weeks and continued until 16.6 weeks. Within this interval, HIG was administered between two and six times in each patient. While CMV immunoglobulin-G (IgG) monitoring showed periodic fluctuations during biweekly HIG administration cycles, high CMV-IgG avidity indices remained stable over the whole treatment period. Maternal-fetal transmission before amniocentesis occurred in only one of the 40 cases (2.5% (95% CI, 0-13.2%)). At delivery, two additional subjects were found to have had late-gestation transmission. Considering all three cases with maternal-fetal transmission, the transmission rate was 7.5% (95% CI, 1.6-20.4%) in our 40 cases. All infected neonates were asymptomatic at birth. The matched historical control group consisted of 108 pregnancies. Thirty-eight transmissions (35.2% (95% CI, 26.2-45.0%)) occurred in the control group, which was significantly higher (P < 0.0001) than the transmission rate in the HIG treatment group. CONCLUSION: After a primary maternal CMV infection in the first trimester, biweekly HIG administration at a dose of 200 IU/kg prevents maternal-fetal transmission up to 20 weeks' gestation. Copyright © 2018 ISUOG. Published by John Wiley & Sons Ltd.

First-trimester ductus venosus velocity ratio as a marker of major cardiac defects.

OBJECTIVES: To examine ductus venosus (DV) flow in fetuses with and those without a cardiac defect and to evaluate different phases of DV flow in addition to the standard assessment of DV pulsatility index for veins (PIV) and the a-wave. METHODS: This was a retrospective study of singleton pregnancies that underwent first-trimester ultrasound screening, which included DV flow assessment, at the University of Tübingen (between 2010 and 2017) or the University of Cologne (between 2013 and 2016). The study population comprised normal fetuses and fetuses with major cardiac defects at a ratio of 10:1. For each fetus, the following parameters of the DV waveform were evaluated: qualitative assessment of the a-wave, PIV measurement and ratios of flow velocities during the S-wave (S) or D-wave (D) and the a-wave (a) or v-wave (v). Reproducibility of DV-PIV and DV flow ratios was evaluated in 30 fetuses in which the DV flow was assessed twice. RESULTS: Our study population included 480 anatomically normal fetuses and 48 with a cardiac defect. Median fetal nuchal translucency (NT) in the normal and in the affected group was 1.9 mm and 2.6 mm, respectively. In five (1.0%) of the normal and 18 (37.5%) of the affected cases, fetal NT thickness was above the 99th centile. In the normal group, the DV a-wave was reversed in 15 (3.1%) cases and the DV-PIV was above the 95th centile in 25 (5.2%). In the cases with cardiac defects, the a-wave was reversed and the DV-PIV measurement was above the 95th centile in 26 (54.2%). The reproducibility of measurement of the ratios of DV flow velocities was similar to that of the DV-PIV. Most cardiac defects were associated with an abnormal a/S or a/D ratio. If the cut-off for these two ratios was set at the 5th centile of the normal distribution, the detection rate of fetal cardiac anomalies would be 62.5%. This compares favorably with the DV-PIV, which detects 26 (54.2%) of the affected fetuses for the same threshold. CONCLUSION: In the first trimester, the a/S ratio has the potential to detect approximately 60% of congenital cardiac defects for a false-positive rate of 5%. Copyright © 2018 ISUOG. Published by John Wiley & Sons Ltd.

Fetal auditory evoked responses to onset of amplitude modulated sounds. A fetal magnetoencephalography (fMEG) study.

The human fetal auditory system is functional around the 25th week of gestational age when the thalamocortical connections are established. Fetal magnetoencephalography (fMEG) provides evidence for fetal auditory brain responses to pure tones and syllables. Fifty-five pregnant women between 31 and 40 weeks of gestation were included in the study. Fetal MEG was recorded during the presentation of an amplitude modulated tone (AM) with a carrier frequency of 500 Hz to the maternal abdomen modulated by low modulation rates (MRs) - 2/s and 4/s, middle MR - 8/s and high MRs - 27/s, 42/s, 78/s and 91/s. The aim was to determine whether the fetal brain responds differently to envelope slopes and intensity change at the onset of the AM sounds. A significant decrease of the response latencies of transient event-related responses (ERR) to high and middle MRs in comparison to the low MRs was observed. The highest fetal response rate was achieved by modulation rates of 2/s, 4/s and 27/s (70%, 57%, and 86%, respectively). Additionally, a maturation effect of the ERR (response latency vs. gestational age) was observed only for 4/s MR. The significant difference between the response latencies to low, middle, and high MRs suggests that still before birth the fetal brain processes the sound slopes at the onset in different integration time-windows, depending on the time for the intensity increase or stimulus power density at the onset, which is a prerequisite for language acquisition.

First-trimester risk assessment based on ultrasound and cell-free DNA vs combined screening: a randomized controlled trial.

OBJECTIVE: This was a randomized controlled trial to compare risk assessment by first-trimester combined screening (FTCS) with an approach that combines a detailed ultrasound examination at 11-13 weeks' gestation and cell-free DNA (cfDNA) analysis. METHODS: Pregnant women with a normal first-trimester ultrasound examination at 11-13 weeks' gestation (fetal nuchal translucency (NT) ≤ 3.5 mm and no fetal defects) were randomized into one of two groups. In the first group, risk of aneuploidy was assessed using FTCS based on the most recent UK Fetal Medicine Foundation algorithm. In the second group, risk assessment was based on ultrasound findings and cfDNA analysis. An additional tube of blood was collected for FTCS in case the cfDNA analysis was uninformative. Primary outcome was false-positive rate in screening for trisomy 21. A case was considered false positive if the karyotype was not trisomy 21 and if the risk for trisomy 21 was >1:100, irrespective of the method of risk calculation. Results were compared using 95% CIs using the Clopper-Pearson method. RESULTS: Between October 2015 and December 2016, 1518 women with singleton pregnancy underwent first-trimester screening. Thirty-one (2.0%) pregnancies were not eligible for randomization due to increased NT (> 3.5 mm) and/or fetal defect. After exclusion of women who declined randomization (n = 87) and cases of fetal death and loss to follow-up (n = 24), 688 pregnancies were randomized into the FTCS arm and 688 into the ultrasound + cfDNA analysis arm. There were no differences in maternal and gestational age, maternal weight and BMI, ethnicity, use of assisted reproduction and cigarette smoking between the two arms. In the ultrasound + cfDNA analysis arm, median risk for trisomy 21 was 1 in 10 000. None of the cases had a risk above 1: 100 (95% CI, 0.0-0.5%). In the FTCS arm, the median risk for trisomy 21 was 1 in 3787 and in 17 cases, the risk was higher than 1:100, which corresponds to 2.5% (95% CI, 1.5-3.9%) of the FTCS study-arm population. CONCLUSION: Our study has shown that first-trimester risk assessment for trisomy 21 that includes a detailed ultrasound examination as well as NT measurement and is followed by cfDNA testing is associated with a significant reduction in the false-positive rate compared with FTCS. This approach obviates the need for maternal serum free ß-human chorionic gonadotropin and pregnancy-associated plasma protein-A in screening for fetal aneuploidy. Copyright © 2017 ISUOG. Published by John Wiley & Sons Ltd.

Sphenofrontal distance in euploid and aneuploid fetuses.

OBJECTIVE: To examine the sphenofrontal distance (SFD) in a large series of aneuploid fetuses in the second and third trimesters and compare findings with those of a euploid population. METHODS: The database at our unit was searched to identify pregnancies with a diagnosis of trisomy 21, 18 or 13, triploidy or Turner syndrome after 15 weeks' gestation. Stored ultrasound images obtained between 19 and 22 weeks were reviewed. For the normal population, two euploid fetuses matched for gestational age were selected randomly for each aneuploid case. The SFD was measured from the anterior edge of the sphenoid bone to the lowest posterior edge of the frontal bone using on-screen calipers. The SFD measurement was parallel to the long axis of the maxilla. If the sphenoid bone did not extend superiorly enough for direct measurement of the SFD, a tangential line was drawn at the anterior wall of the sphenoid bone and extended cranially. In these cases, the distance between the extended line and the frontal bone was measured. One operator measured the SFD twice and was blinded to the results and karyotype. RESULTS: The study population consisted of 591 pregnancies: 394 euploid fetuses, 122 fetuses with trisomy 21, 45 with trisomy 18, 16 with trisomy 13, eight with Turner syndrome and six with triploidy. For both euploid and aneuploid groups, mean gestational age at examination was 22.8 (range: euploid, 15.0-40.7; aneuploid, 15.0-40.3) weeks. For euploid fetuses, mean SFD was 1.27 cm and measurements ranged from 0.53 cm to 2.56 cm. SFD was significantly dependent on gestational age (SFD = 0.138 + 0.005 × gestational age, P < 0.001, r = 0.802). Mean SFD was significantly smaller in each aneuploid group compared with the euploid population (trisomies 21, 18 and 13: all P < 0.001; triploidy: P = 0.026; Turner syndrome: P = 0.047). For 32 (26.2%), nine (20.0%) and six (37.5%) fetuses with trisomy 21, 18 and 13, respectively, SFD was < 5th percentile. Only one (12.5%) fetus with Turner syndrome and none with triploidy had SFD < 5th percentile. CONCLUSION: In aneuploid fetuses, the SFD is smaller than in their euploid counterparts. However, for a false-positive rate of 5%, the detection rate of trisomy 21 is only 26%. Therefore, using the method we have proposed, it is unlikely that this marker will play a major role in second- and third-trimester screening for aneuploidy. Copyright © 2016 ISUOG. Published by John Wiley & Sons Ltd.

Comparison of Errors of 35 Weight Estimation Formulae in a Standard Collective.

Issue: The estimation of foetal weight is an integral part of prenatal care and obstetric routine. In spite of its known susceptibility to errors in cases of underweight or overweight babies, important obstetric decisions depend on it. In the present contribution we have examined the accuracy and error distribution of 35 weight estimation formulae within the normal weight range of 2500-4000 g. The aim of the study was to identify the weight estimation formulae with the best possible correspondence to the requirements of clinical routine. Materials and Methods: 35 clinically established weight estimation formulae were analysed in 3416 foetuses with weights between 2500 and 4000 g. For this we determined and compared the mean percentage error (MPE), the mean absolute percentage error (MAPE), and the proportions of estimates within the error ranges of 5, 10, 20 and 30 %. In addition, separate regression lines were calculated for the relationship between estimated and actual birth weights for the weight range 2500-4000 g. The formulae were thus examined for possible inhomogeneities. Results: The lowest MPE were achieved with the Hadlock III and V formulae (0.8 %, STW 9.2 % or, respectively, -0.8 %, STW 10.0 %). The lowest absolute error (6.6 %) as well as the most favourable frequency distribution in cases below 5 % and 10 % error (43.9 and 77.5) were seen for the Halaska formula. In graphic representations of the regression lines, 16 formulae revealed a weight overestimation in the lower weight range and an underestimation in the upper range. 14 formulae gave underestimations and merely 5 gave overestimations over the entire tested weight range. Conclusion: The majority of the tested formulae gave underestimations of the actual birth weight over the entire weight range or at least in the upper weight range. This result supports the current strategy of a two-stage weight estimation in which a formula is first chosen after a pre-estimation of the weight range.