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Aims: Previous studies suggested that head circumference (HC) predicts the date of confinement better than the biparietal diameter (BPD). The present study aimed to prospectively test this assumption. Methods: A prospective study including 4179 consecutive women attending the second trimester routine ultrasound examination at 17-20 weeks of gestation. Outer-outer BPD and HC were determined as the average of three repeated measurements. Twins were excluded. Time of delivery was noted, the differences between this and the predicted date of delivery calculated with HC and BPD (based on a pregnancy duration of 282 days), and the two methods were compared using Wilcoxon signed rank test. Results: For the entire group, the median differences between actual and predicted delivery with HC and BPD were 0.9 and 1.2 days, respectively. For deliveries with a spontaneous onset of labor (n=3336) the corresponding differences were 0.9 and 1.4 days. The difference between the HC and BPD methods was significant (P<0.0001). In the group of spontaneous onset of labor, there were 05.6% post-term pregnancies (>/=296 days) according to HC and 5.7% according to BPD. Conclusion: Provided that the expected pregnancy duration was 282 days, both HC and BPD predicted spontaneous birth with a mean accuracy of one day, HC being significantly better than BPD. [ABSTRACT FROM AUTHOR]

Introduction: The human yolk sac provides the embryo with stem cells, nutrients, and gas exchange. We hypothesized that more maternal resources, reflected in body size and body composition, would condition a a larger yolk sac, ensuring resources for the growing embryo. Thus, we aimed to determine the relation between maternal size in early pregnancy and yolk sac size., Material and Methods: This subsidiary study was embedded in the multinational World Health Organization fetal growth project that included healthy women with a body mass index of 18-30, reliable information of their regular last menstrual period and singleton pregnancies. Yolk sac diameter, crown-rump length, and maternal height, weight, body mass index, and body composition were assessed before 13 weeks of gestation, and the fetal biometry was repeated during the pregnancy., Results: Of 140 participants, 122 with a successful yolk sac measurement were entered in the present analysis. Maternal weight was negatively associated with the yolk sac diameter (P = 0.007) and so was maternal height (P = 0.011), fat mass (P = 0.037), and lean body mass (P = 0.018), but not body mass index (P = 0.121). Significant effects were predominantly due to the female embryos and could be traced at 24 weeks of gestation. That is, a small yolk sac : crown-rump length ratio in early pregnancy was associated with a high fetal abdominal circumference (P < 0.001) and estimated fetal weight (P = 0.001)., Conclusions: The human yolk sac is involved in the regulation of embryonic growth, but contrary to our hypothesis, the yolk sac has a compensatory capacity, being larger when the mothers are smaller; and the effect can be traced on fetal size at 24 weeks of gestation., (© 2018 Nordic Federation of Societies of Obstetrics and Gynecology.)

Introduction: Fetal biometry is used for determining gestational age and estimated date of delivery (EDD). However, the accuracy of the EDD depends on the assumed length of pregnancy included in the calculation. This study aimed at assessing the actual pregnancy length and accuracy of EDD prediction based on fetal head circumference measured at the second trimester., Material and Methods: This was a population-based observational study with the following inclusion criteria: singleton pregnancy, head circumference dating in the second trimester, spontaneous onset or induction of delivery ≥ 294 days of gestation, live birth. The EDD was set anticipating a pregnancy length of 282 days. Bias in the prediction of EDD was defined as the difference between the actual date of birth and the EDD., Results: Head circumference measurements were available for 21 451 pregnancies. Ultrasound-dated pregnancies had a median pregnancy length of 283.03 days, corresponding to a method bias of 1.03 days (95% CI; 0.89-1.16). This bias was dependent on the head circumference at dating, ranging from -1.58 days (95% CI; -3.54 to 1.12) to 3.42 days (95% CI; 1.98-4.31). The median pregnancy length, based on the last menstrual period of women with a regular menstrual cycle (n = 12 985), was 283.15 days (95% CI; 282.91-283.31). A total of 5685 (22.9%, 95% CI; 22.4% to 23.4%) and 886 women (3.6%, 95% CI; 3.3%-3.8%) were still pregnant 7 and 14 days after the EDD, respectively., Conclusions: Second trimester head circumference measurements can be safely used to predict EDD. A revision of the pregnancy length to 283 days will reduce the bias of EDD prediction to a level comparable with other methods., (© 2018 Nordic Federation of Societies of Obstetrics and Gynecology.)

Objectives: Investigate cardiorespiratory outcomes in children surviving previable preterm premature rupture of membranes (PV-PPROM) before 22 weeks' gestational age (GA) with minimum 2 weeks latency., Study Design: Single institution, follow-up of retrospectively identified children who were born after PV-PPROM during 2000-2004, and individually matched preterm-born controls., Results: Eleven PV-PPROM and matched control children were included at mean age of 10.5 and 10.7 years. Rupture of membranes occurred at mean GA 18 2 and 27 6 weeks and birth at 28 3 and 28 6 weeks, respectively. Compared to controls, the PV-PPROM group had significantly poorer lung function, findings on echocardiography indicating mild pulmonary hypertension, and lower peak oxygen consumption. Chart reviews suggested more motor difficulties and a tendency towards more problems with learning and attention., Conclusion: The findings highlight a preterm-born sub-group in need of targeted long-term monitoring and possibly interventions regarding future cardiorespiratory and neurodevelopmental function.

Introduction: Anomalous cord insertion is associated with increased risk of adverse maternal and perinatal outcome. Our aim was to study whether anomalous cord insertion is associated with prelabor rupture of membranes (PROM), preterm PROM (pPROM), long or short umbilical cord, and time trend of spontaneous preterm birth (SPTB) and anomalous cord insertion., Material and Methods: A population-based register study using data from the Medical Birth Register of Norway including all singleton births (gestational age >16 weeks and <45 weeks) during 1999-2013 (n = 860 465) to calculate odds ratios (ORs) for PROM, pPROM, SPTB, and cord length (>95th or <5th centile) according to the cord insertion site by logistic regression with adjustment for possible confounders. We also assessed time trends of SPTB and anomalous cord insertion., Results: Velamentous insertion of the cord was associated with an increased risk of PROM (OR 1.6, 95% CI 1.5-1.7), pPROM (OR 2.7, 95% CI 2.4-3.0), SPTB (OR 2.0, 95% CI 1.9-2.2), and a short cord (OR 1.7, 95% CI 1.5-1.8). Marginal insertion was to a lesser extent associated with these complications. Occurrences of SPTB and anomalous insertion declined. The decline in SPTB persisted after including an interaction term between anomalous insertion and time., Conclusions: Velamentous and, to a lesser extent, marginal cord insertions were associated with increased risk of PROM, pPROM, SPTB, and short cord. This suggests a common pathogenesis behind altered function of the membranes, cord, and placenta. The decline in SPTB could not be explained by the reduction in the occurrence of anomalous cord insertion., (© 2016 Nordic Federation of Societies of Obstetrics and Gynecology.)

Objective: To test whether adding conditional growth centiles to size centiles of estimated fetal weight (EFW) improves prediction of adverse perinatal outcome in pregnancies with or at risk of having a small-for-gestational-age (SGA) fetus., Methods: This prospective longitudinal study included pregnant women at risk of or diagnosed with an SGA (≤ 5(th) centile) fetus. They underwent serial ultrasound measurements and the final two were included in the analyses for this study. The EFW was categorized into normal (> 5(th) or 10(th) centile) and abnormal (≤ 5(th) or 10(th) centile) for size and conditional growth before entering the variables into log-binomial regression analyses. Adverse outcomes were delivery < 37 weeks, operative delivery due to fetal distress, 5-min Apgar score < 7, newborn hypoglycemia (glucose < 2.0 mmol/L), admission to the neonatal intensive care unit and perinatal mortality. A combined outcome variable ('any adverse outcome') included one or more adverse outcomes., Results: Complete biometric data were obtained for 211 women. Conditional growth and size centiles contributed independently to the prediction of adverse outcome. Combining conditional growth and size centiles significantly improved the prediction of outcomes compared with size centiles alone (e.g. for 5(th) centile cut-off for any adverse outcome, P = 0.023, log-likelihood test). Using a 5(th) centile threshold, for any adverse outcome, the specificity of 78% (95% CI, 70-84%) using size centile as a predictor was improved to 94% (95% CI, 89-97%) when conditional growth centile was added to the model, whereas the sensitivity was not significantly changed (60% (95% CI, 49-69%) vs 39% (95% CI, 30-50%))., Conclusions: Size centiles and conditional growth centiles contribute independently to the prediction of adverse perinatal outcome, and their combination further improves the prediction model. The results support an increased use of conditional growth centiles in the monitoring of fetuses at risk. Copyright © 2015 ISUOG. Published by John Wiley & Sons Ltd., (Copyright © 2015 ISUOG. Published by John Wiley & Sons Ltd.)

Introduction: Centiles of middle cerebral artery pulsatility index and cerebroplacental ratio are useful for predicting adverse perinatal outcomes. A 'conditional centile' is conditioned by a previous measurement reflecting degree of individual change over time. Here we test whether such centiles are independent predictors and whether their combination improves prediction., Material and Methods: This prospective longitudinal study included 220 pregnant women diagnosed with or at risk of having a small-for-gestational-age fetus. Serial Doppler measurements of the umbilical artery and middle cerebral artery pulsatility indexs were used to calculate cerebroplacental ratio. Preterm birth, operative delivery due to fetal distress, admission to neonatal intensive care unit, 5-min Apgar score <7, newborn hypoglycemia, and perinatal mortality were considered adverse outcomes. Possible associations were analyzed by log-binomial regression analysis., Results: Serial Doppler measurements of the middle cerebral artery were available in 207 participants and cerebroplacental ratio in 205. Conditional centiles ≤5 and ≤10 for both middle cerebral artery pulsatility index and cerebroplacental ratio were associated with increased risk for adverse perinatal outcomes. However, only the combination of cerebroplacental ratio centile and conditional centile ≤10 showed a better performance in the prediction of operative delivery due to fetal distress (p = 0.032), admission to neonatal intensive care unit (p = 0.048), and the combined variable "any adverse outcomes" (p = 0.034) compared with the use of centile ≤10 alone., Conclusions: Conditional centile for middle cerebral artery pulsatility index and cerebroplacental ratio ≤5 and ≤10 are associated with adverse perinatal outcomes. When adding conditional centile to conventional centile for cerebroplacental ratio, the prediction improved compared with the use of conventional centile alone., (© 2016 Nordic Federation of Societies of Obstetrics and Gynecology.)

Objective: To assess whether anomalous cord insertion is associated with risk of complications in the third stage of labor., Design: A population-based study., Setting: Norwegian Medical Birth Register., Population: All singleton births (gestational age >16 weeks and <45 weeks) during the period 1999-2011 (n = 738,443 singletons). Deliveries by cesarean were excluded, leaving 628,680 vaginal singleton deliveries for the analyses., Methods: Calculation of odds ratios for complications in the third stage of labor (postpartum hemorrhage, manual delivery of the placenta, curettage) in velamentous and marginal cord insertion by logistic regression with adjustment for confounders., Main Outcome Measures: Complications in the third stage of labor, postpartum hemorrhage, manual placental removal and curettage., Results: Anomalous cord insertion was associated with an increased risk of complications in the third stage of labor, the risk being higher for velamentous than for marginal insertion. The risks persisted after adjusting for possible confounding factors. Velamentous cord insertion carried a 5.6% risk of a need for manual removal of the placenta, compared with the risk of 1.1% for nonvelamentous insertion (odds ratio = 5.21, 95% confidence interval 4.71-5.76) in vaginal delivery, and we found increased risks of curettage (odds ratio = 3.29, 95% confidence interval 2.87-3.77) and postpartum hemorrhage (odds ratio = 2.06, 95% confidence interval 1.77-2.39)., Conclusions: Marginal and especially velamentous cord insertion is associated with an increased risk of hemorrhage in the third stage of labor, need for manual removal of the placenta and curettage. Anomalous cord insertion can be identified prenatally and so possibly influence obstetric management., (© 2015 Nordic Federation of Societies of Obstetrics and Gynecology.)

Background: In 2006 WHO presented the infant and child growth charts suggested for universal application. However, major determinants for perinatal outcomes and postnatal growth are laid down during antenatal development. Accordingly, monitoring fetal growth in utero by ultrasonography is important both for clinical and scientific reasons. The currently used fetal growth references are derived mainly from North American and European population and may be inappropriate for international use, given possible variances in the growth rates of fetuses from different ethnic population groups. WHO has, therefore, made it a high priority to establish charts of optimal fetal growth that can be recommended worldwide., Methods: This is a multi-national study for the development of fetal growth standards for international application by assessing fetal growth in populations of different ethnic and geographic backgrounds. The study will select pregnant women of high-middle socioeconomic status with no obvious environmental constraints on growth (adequate nutritional status, non-smoking), and normal pregnancy history with no complications likely to affect fetal growth. The study will be conducted in centres from ten developing and industrialized countries: Argentina, Brazil, Democratic Republic of Congo, Denmark, Egypt, France, Germany, India, Norway, and Thailand. At each centre, 140 pregnant women will be recruited between 8 + 0 and 12 + 6 weeks of gestation. Subsequently, visits for fetal biometry will be scheduled at 14, 18, 24, 28, 32, 36, and 40 weeks (+/- 1 week) to be performed by trained ultrasonographers.The main outcome of the proposed study will be the development of fetal growth standards (either global or population specific) for international applications., Discussion: The data from this study will be incorporated into obstetric practice and national health policies at country level in coordination with the activities presently conducted by WHO to implement the use of the Child Growth Standards.

Objectives: To determine the prevalence of, and risk factors for anomalous insertions of the umbilical cord, and the risk for adverse outcomes of these pregnancies., Design: Population-based registry study., Setting: Medical Birth Registry of Norway 1999-2009., Population: All births (gestational age >16 weeks to <45 weeks) in Norway (623,478 singletons and 11,263 pairs of twins)., Methods: Descriptive statistics and odds ratios (ORs) for risk factors and adverse outcomes based on logistic regressions adjusted for confounders., Main Outcome Measures: Velamentous or marginal cord insertion. Abruption of the placenta, placenta praevia, pre-eclampsia, preterm birth, operative delivery, low Apgar score, transferral to neonatal intensive care unit (NICU), malformations, birthweight, and perinatal death., Results: The prevalence of abnormal cord insertion was 7.8% (1.5% velamentous, 6.3% marginal) in singleton pregnancies and 16.9% (6% velamentous, 10.9% marginal) in twins. The two conditions shared risk factors; twin gestation and pregnancies conceived with the aid of assisted reproductive technology were the most important, while bleeding in pregnancy, advanced maternal age, maternal chronic disease, female foetus and previous pregnancy with anomalous cord insertion were other risk factors. Velamentous and marginal insertion was associated with an increased risk of adverse outcomes such as placenta praevia (OR = 3.7, (95% CI = 3.1-4.6)), and placental abruption (OR = 2.6, (95% CI = 2.1-3.2)). The risk of pre-eclampsia, preterm birth and delivery by acute caesarean was doubled, as was the risk of low Apgar score, transferral to NICU, low birthweight and malformations. For velamentous insertion the risk of perinatal death at term was tripled, OR = 3.3 (95% CI = 2.5-4.3)., Conclusion: The prevalence of velamentous and marginal insertions of the umbilical cord was 7.8% in singletons and 16.9% in twin gestations, with marginal insertion being more common than velamentous. The conditions were associated with common risk factors and an increased risk of adverse perinatal outcomes; these risks were greater for velamentous than for marginal insertion.

Objectives: The superior vena cava (SVC) drains venous blood from the upper foetal body, mainly the head. Data on the human foetus is scarce. Here we present reference values for the blood flow during the second half of pregnancy, and test the hypothesis that foetal breathing movements (FBM) enhance this flow., Methods: Based on a power calculation, 110 women with low-risk singleton pregnancies were recruited to a longitudinal study that included three sets of observations during the second half of pregnancy. Ultrasound was used to determine inner diameter, peak systolic blood velocity and time-average maximum velocities in the SVC during rest and respiratory activity., Results: During the second half of pregnancy, SVC blood flow increased from 57.8 mL/min (95% CI 51.7-64.3) to 221.5 (204.5-239.3). Based on 558 sets of observations obtained during foetal rest and FBM, we found an overall increase in diameter from 0.41 cm (0.40-0.42) to 0.46 (0.44-0.48), peak systolic velocity from 35.9 cm/s (34.9-37.0) to 62.2 (59.1-65.5), and time-averaged maximum velocity from 20.3 cm/s (19.7-20.8) to 27.3 (26.1-28.6). This resulted in an overall 90% increase in mean SVC blood flow, from 108.1 mL/min (98.8-117.9) at rest to 205.9 (183.2-230.5) during FBM., Conclusion: The blood flow in the SVC increases during the second half of pregnancy and is substantially augmented during FBM. Since high-amplitude FBM additionally reduces flow in the inferior vena cava, the net effect is a prioritised venous drainage from the foetal head enhancing the washout of CO(2) in that area, which also contains the chemoreceptors., (Copyright © 2011 Elsevier Ireland Ltd. All rights reserved.)

Objective: Based on the hypothesis that fetal breathing movements (FBM) enhance sections of the circulation to meet the needs of gas transport, we studied the effects of FBM on the fetal inferior vena cava (IVC), which transports blood with the lowest oxygen saturation in the fetal body., Methods: One-hundred and ten women with low-risk singleton pregnancies were included in a longitudinal study during the second half of pregnancy. Inner diameter, peak systolic velocity and time-averaged maximum blood velocity were measured in the IVC below the ductus venosus outlet during rest and FBM. Volume flow and pressure gradient were estimated in 55 observations of forced inspiratory movements at 36 weeks of gestation. The results are presented as mean and 95% CI of the mean., Results: Based on 585 observations obtained during fetal rest and FBM, we found no difference in diameter, 0.42 (95% CI, 0.41-0.43) cm vs. 0.41 (95% CI, 0.39-0.42) cm, respectively, apart from during high-amplitude inspiratory movement, when the diameter was 0.15 (95% CI, 0.13-0.17) cm. The peak systolic velocity was different during rest and FBM, 34.0 (95% CI, 32.7-35.3) cm/s vs. 81.5 (95% CI, 76.2-87.5) cm/s, respectively, and correspondingly for time-averaged maximum velocity, 19.7 (95% CI, 18.9-20.5) cm/s vs. 37.2 (95% CI, 34.9-39.9) cm/s, respectively. Forced inspiratory movements at 36 weeks significantly reduced flow in the IVC compared with rest, 63.6 (95% CI, 44.4-88.1) mL/min vs. 186.0 (95% CI, 142.8-238.1) mL/min, respectively. The pressure gradient increased 14-fold during forced inspiration, from 0.64 to 8.76 mmHg., Conclusions: High-amplitude fetal inspiration substantially constricts the abdominal IVC and creates a negative pressure in the chest. The IVC constriction withholds abdominal blood, thus temporarily giving way to other flows., (Copyright © 2011 ISUOG. Published by John Wiley & Sons, Ltd.)

Objective: To study the association between maternal weight gain in pregnancy and fetal abdominal circumference in the second trimester., Design: Prospective cross-sectional study., Setting: Low-risk antenatal clinic., Population: Six hundred and fifty women with low-risk pregnancy., Methods: Women with a regular menstrual period (28±4 days) and certain information on the last menstrual period were recruited when they were referred for routine ultrasound scanning. Women with a discrepancy of>14 days between ultrasound and menstrual age were excluded. Maternal weight gain during pregnancy was derived from information in the antenatal chart and the weekly weight gain was calculated. Fetal abdominal circumference measurements were registered in gestational weeks 15-25 and their z-scores, together with the z-scores of maternal weight gain, were used in a linear regression analysis. Main outcome measures. Association between maternal weight gain and fetal abdominal circumference., Results: Based on the complete data of 515 women we found a mean maternal weight gain during pregnancy of 0.39 kg/week and a positive association between this weight gain and fetal abdominal circumference in the second trimester (r=0.122 (95%CI 0.051-0.194)), with the strongest effect in women with the slowest weight gain (<0.28 kg/week) (r=0.554 (95%CI 0.261-0.846))., Conclusion: Maternal weight gain in pregnancy is related to and may determine fetal abdominal circumference in gestational weeks 15-25, particularly in those women with a slow weight gain., (© 2011 The Authors Acta Obstetricia et Gynecologica Scandinavica© 2011 Nordic Federation of Societies of Obstetrics and Gynecology.)

Objectives: In humans, fetal breathing movements affect blood velocities in the umbilical vein and artery, but it is not known whether fetal respiratory activity is associated with increased fetal blood flow through the placenta. We therefore tested this hypothesis in the present study., Methods: One-hundred and ten women with low-risk singleton pregnancies were each examined three times by ultrasound during the second half of pregnancy. Fetal heart rate, umbilical artery blood velocity, umbilical vein diameter and blood velocity, and umbilical blood flow at the placental end were determined during fetal rest and fetal respiratory movements., Results: Based on 330 observations obtained during fetal rest or breathing activity, no difference was found in the mean fetal heart rate (beats per minute (bpm)) during rest compared with breathing (142 bpm vs. 142 bpm, respectively). Although fetal breathing affected the umbilical artery waveform, there was no difference in the mean time-averaged maximum velocity between rest and breathing: 26.6 (95% CI, 25.1-28.3) cm/s vs. 28.9 (95% CI, 27.2-30.7) cm/s, respectively. The umbilical vein was 27% greater in cross-sectional area and the blood velocity 9% higher during breathing, resulting in a 42% increase in mean umbilical blood flow: 121.8 (95% CI, 109.5-135.0) mL/min at rest vs. 173.0 (95% CI, 158.0-188.6) mL/min during breathing. Venous velocity was calculated from recordings of mean duration 3.7 s at rest and 6.2 s of respiratory activity. Gestational age did not influence the relationship., Conclusion: Fetal breathing is associated with increased umbilical blood flow during the second half of pregnancy. Umbilical vein distension during breathing suggests active endocrine regulation., (Copyright © 2010 ISUOG. Published by John Wiley & Sons, Ltd.)

Bone size is a determinant of bone strength and tracks in its percentile of origin during childhood and adolescence. We hypothesized that the ranking of an individual's femur length (FL) is established in early gestation and tracks thereafter. Fetal FL was measured serially using 2D ultrasound in 625 Norwegian fetuses. Tracking was assessed using Pearson correlation, a generalized estimating equation model, and by calculating the proportion of fetuses whose FL remained within the same quartile. Baseline FL Z-score (weeks 10 to 19) and later measurements correlated, but more weakly as gestation advanced: r = 0.59 (weeks 20 to 26); r = 0.45 (weeks 27 to 33); and r = 0.32 (weeks 34 to 39) (p < 0.001). Tracking within the same quartile throughout gestation occurred in 13% of fetuses. Of the 87% deviating, 21% returned to the quartile of origin, so 34% began and ended in the same quartile, 38% deviated by one quartile, and 28% deviated by two or more quartiles by the end of gestation. A standard deviation higher baseline FL Z-score, placental weight (150 g), maternal height (5 cm), and weight (10 kg), was associated with a 0.25, 0.15, 0.10, and 0.05 SD higher FL Z-score at the end of gestation, respectively (p ranging from <0.001 to 0.02). Tracking within the same percentile throughout the whole of gestation, as suggest by growth charts, is uncommon. Deviation from tracking is more common and is the result of changes in growth velocity within and between fetuses and is partly influenced by maternal, fetal, and placental factors., ((c) 2010 American Society for Bone and Mineral Research.)

Background: The African population is composed of a variety of ethnic groups, which differ considerably from each other. Some studies suggest that ethnic variation may influence dating. The aim of the present study was to establish reference values for fetal age assessment in Cameroon using two different ethnic groups (Fulani and Kirdi)., Methods: This was a prospective cross sectional study of 200 healthy pregnant women from Cameroon. The participants had regular menstrual periods and singleton uncomplicated pregnancies, and were recruited after informed consent. The head circumference (HC), outer-outer biparietal diameter (BPDoo), outer-inner biparietal diameter and femur length (FL), also called femur diaphysis length, were measured using ultrasound at 12-22 weeks of gestation. Differences in demographic factors and fetal biometry between ethnic groups were assessed by t- and Chi-square tests., Results: Compared with Fulani women (N = 96), the Kirdi (N = 104) were 2 years older (p = 0.005), 3 cm taller (p = 0.001), 6 kg heavier (p < 0.0001), had a higher body mass index (BMI) (p = 0.001), but were not different with regard to parity. Ethnicity had no effect on BPDoo (p = 0.82), HC (p = 0.89) or FL (p = 00.24). Weight, height, maternal age and BMI had no effect on HC, BPDoo and FL (p = 0.2-0.58, 0.1-0.83, and 0.17-0.6, respectively). When comparing with relevant European charts based on similar design and statistics, we found overlapping 95% CI for BPD (Norway & UK) and a 0-4 day difference for FL and HC., Conclusion: Significant ethnic differences between mothers were not reflected in fetal biometry at second trimester. The results support the recommendation that ultrasound in practical health care can be used to assess gestational age in various populations with little risk of error due to ethnic variation.

Background: Conventionally, the pregnancy duration is accepted to be 280-282 days. Fetuses determined by ultrasound biometry to be small in early pregnancy, have an increased risk of premature birth. We speculate that the higher rate of preterm delivery in such small fetuses represents a pathological outcome not applicable to physiological pregnancies. Here we test the hypothesis that in low-risk pregnancies fetal growth (expressed by fetal size in the second trimester) is itself a determinant for pregnancy duration with the slower growing fetuses having a longer pregnancy., Methods: We analysed duration of gestation data for 541 women who had a spontaneous delivery having previously been recruited to a cross-sectional study of 650 low-risk pregnancies. All had a regular menses and a known date of their last menstrual period (LMP). Subjects were examined using ultrasound to determine fetal head circumference (HC), abdominal circumference (AC) and femur length (FL) at 10-24 weeks of gestation. Length of the pregnancy was calculated from LMP, and birth weights were noted. The effect of fetal size at 10-24 weeks of gestation on pregnancy duration was assessed also when adjusting for the difference between LMP and ultrasound based fetal age., Results: Small fetuses (z-score -2.5) at second trimester ultrasound scan had lower birth weights (p < 0.0001) and longer duration of pregnancy (p < 0.0001) than large fetuses (z-score +2.5): 289.6 days (95%CI 288.0 to 291.1) vs. 276.1 (95%CI 273.6 to 278.4) for HC, 289.0 days (95%CI 287.4 to 290.6) vs. 276.9 days (95%CI 274.4 to 279.2) for AC and 288.3 vs. 277.9 days (95%CI 275.6 to 280.1) for FL. Controlling for the difference between LMP and ultrasound dating (using HC measurement), the effect of fetal size on pregnancy length was reduced to half but was still present for AC and FL (comparing z-score -2.5 with +2.5, 286.6 vs. 280.2 days, p = 0.004, and 286.0 vs. 280.9, p = 0.008, respectively)., Conclusion: Fetal size in the second trimester is a determinant of birth weight and pregnancy duration, small fetuses having lower birth weights and longer pregnancies (up to 13 days compared with large fetuses). Our results support a concept of individually assigned pregnancy duration according to growth rates rather than imposing a standard of 280-282 days on all pregnancies.

Objectives: The aims of the present study were to establish improved reference charts for growth of the fetal head, abdomen and femur, and to determine the effect of fetal and maternal factors., Study Design: This prospective longitudinal study included 650 low-risk pregnancies. Outer-outer biparietal diameter (BPD), head circumference (HC), mean abdominal diameter (MAD), abdominal circumference (AC) and femur length (FL) were measured by ultrasound, and the statistical analysis was based on regression analysis and multilevel modeling., Results: Reference percentiles for the growth of MAD, AC and FL showed continuous growth in gestational week 10-40, while BPD and HC showed a slightly blunted growth toward the end of pregnancy. FL was the only variable that was not influenced by gender. There was a significant negative association between breech presentation and all five biometrical variables, while maternal weight was positively associated with all five variables. Cephalic index significantly influenced BPD and HC. Maternal height had a positive effect on BPD, HC, AC and FL, and parity had a positive effect on MAD and AC, while smoking influenced negatively HC, MAD, and FL. Terms for calculating conditional reference values and customisation for individualised growth assessment are presented., Conclusions: New reference charts for the growth of fetal head, abdomen and femur are suggested for assessing fetal size and growth, and can be adjusted for maternal and fetal factors to suite individual pregnancies.

Objective: The aims of the present study were to establish reference ranges for the growth of estimated fetal weight (EFW) between gestational weeks 20 and 42 and to determine the effect of fetal and maternal factors., Methods: This prospective longitudinal study was based on 634 low-risk pregnancies and a total of 1799 examinations. Gestational age was computed from last menstrual period. Head circumference, abdominal circumference, and femur length were measured using ultrasound, and EFW was calculated using the formula of Combs et al. The statistical analysis was based on regression analysis and multilevel modeling., Results: Intrauterine growth expressed by EFW showed a continuous pattern until term. Males were calculated to be 5% heavier than female fetuses at 20 gestational weeks and 3% at 40 weeks. Otherwise, the fetal and maternal effects on intrauterine growth correspond to a weight shift of 1.3% for breech/nonbreech, 2.5% for each increase in maternal height tertile, and -4% for smoking/nonsmoking. Maternal age higher than 34 years had a significant increased EFW of 4.5% compared with maternal age less than 24 years. Cephalic index in the third tertile had a 1.1% lower EFW compared with the first tertile. Maternal weight, body mass index, and parity did not influence the EFW. Terms for customization to individualize the growth patterns are presented., Conclusions: The present growth chart is recommended as robust reference ranges for assessing EFW and growth. Fetal and maternal variables can be added into the models to individualize the prediction of EFW.

Background: The aim of the present study is to establish new reference charts for gestational age assessment based on fetal femur length (FL), and new reference ranges for FL to head ratios at gestational weeks 10-25, and to determine the effect of maternal and fetal factors on these charts., Methods: Six hundred fifty low-risk women with regular menstrual periods and singleton pregnancies were recruited to a prospective cross-sectional study after obtaining written consent. FL, outer-outer biparietal diameter (BPD), and head circumference (HC) were measured at 10-25 weeks of gestation. We used regression analysis in order to construct mean curves and to assess the effect of maternal and fetal factors on age assessment., Results: The new chart for age assessment by means of FL was based on 636 measurements. The 95% CI of the mean corresponded to <1 day. The variation between the mean and the 90th percentile was 5, 6, and 7 days at 13, 18, and 23 weeks, respectively, similar to the results when using BPD or HC. Maternal age modestly influenced gestational age assessment (1.3 days/10 years, P = 0.005), whereas smoking, height, body mass index, multiparity, fetal sex, cephalic index, and breech presentation had no impact. Reference charts for FL to head ratios have been presented. Maternal age, fetal sex, and cephalic index influenced the FL/BPD ratio, whereas only fetal sex influenced FL/HC., Conclusions: Fetal age assessment based on FL is an equally robust method as using HC. FL/HC is a more robust ratio to characterize fetal proportions than is FL/BPD.

Background: Maternal height and weight have increased during the past 20 years, as has birthweight. The aim of the present study was to establish new reference charts for gestational age (GA) assessment using fetal biparietal diameter (BPD) and head circumference (HC), and to determine the effect of maternal and fetal factors on age assessment., Methods: This was a prospective, cross-sectional study of 650 healthy women with regular menstrual periods and singleton uncomplicated pregnancies, recruited after written consent. BPD (outer-outer) and HC were measured at 10-24 weeks of gestation. We used regression analysis to construct mean curves and assess the effect of maternal and fetal factors on age assessment., Results: BPD and HC were successfully measured in 642 participants. Using BPD and HC before 20 weeks, the new charts gave 3-8 days higher GA assessment than the charts presently in use, and <1 day difference compared to other recently established charts. Maternal age, multiparity, fetal gender, breech position and shape of fetal head affect GA estimation by 1-2 days when using BPD (p = 0.0001-0.02). Only maternal age and fetal gender affected GA estimation when using HC (

Background: To evaluate the treatment and neonatal outcome in pregnancies complicated by twin-twin transfusion syndrome (TTS)., Material and Methods: Twenty-four women with TTS were identified in the period 1993-99 among 34477 deliveries. We include a retrospective chart review of all twins with TTS., Results: The overall incidence of TTS was 4.75% of all twin pregnancies. The mean gestational age at the time of diagnosing TTS was 23 weeks (range 17.6-38), and the mean gestational age at delivery was 34.6 weeks (range 23.1-38.3). Therapeutic amniocenteses was performed in 21 women. The total volume drained varied from 0.4 to 32.31 with a mean of 2.3 l. Overall perinatal mortality in TTS was 35.4%, as nine donor twins and eight recipient twins died. The main causes for mortality were intrauterine death and prematurity., Conclusion: Twin-twin transfusion syndrome is a severe complication in monochorionic diamniotic twin pregnancies, with high perinatal mortality and morbidity even though amnioreduction prolonged the pregnancies leading to better neonatal outcome.

Background: Medical abortion was first introduced in Norway in April 1998. The aim of this study is to assess the efficacy, side effects and acceptability of medical abortion with mifepristone and vaginally administered misoprostol in a Norwegian population., Materials and Methods: The study included the first consecutive 226 women with gestational age of < 63 days who requested non-surgical abortion in the first year at the first Norwegian hospital using this regime. All women received a single dose of mifepristone 600 mg orally followed by 800 microgram of misoprostol vaginally after 48 hours. Complications were the principal outcome measure. We also took note of side effects such as abdominal pain and bleeding and inquired about how acceptable the treatment was for the women concerned., Results: 95 % of the women had an uncomplicated termination of their pregnancies. The side effects were few and tolerable and the method's acceptability high., Interpretation: The combination of mifepristone and vaginally administered misoprostol is effective and safe, has few side effects, and is well accepted by Norwegian women.

Objectives: Medical abortion was first introduced in Norway in April 1998. The aims of this study were to assess the efficacy, side effects, and acceptability of medical abortion using mifepristone orally and misoprostol vaginally in a Norwegian population., Design: The study included the first 226 pregnant women with gestational age of <63 days who requested nonsurgical abortion during the first year in the first Norwegian hospital using this regimen., Methods: All women received a single dose of mifepristone 600 mg orally, followed at 48 hours by 800 microg misoprostol vaginally. Treatment outcome and complications were the principal outcome measures. We also measured the rates of side effects such as abdominal pain and bleeding and the women's acceptability of treatment., Results: Abortion was successful in 95%, surgical evacuation became necessary in 4%, and the pregnancy continued in one woman. During the study period the method was chosen by 23% of those requesting abortion before 63 days amenorrhea; 80% would use the method again; 81% would recommend it to a friend; in retrospect, 69% would not have been willing to be randomly allocated to either a medical or a surgical method., Conclusions: The combination of orally administrated mifepristone and vaginally administrated misoprostol is an abortion method that is both effective and safe, has few side effects and is well accepted by Norwegian women.

Background: Vaginal agenesia appears among 1 in 5,000-10,000 newborn girls, i.e. 3-6 patients per year in Norway., Material and Methods: From 1975 to 1998, 14 women (mean age 20 years) were operated for vaginal agenesia by McIndoe's method at Haukeland University Hospital. Twelve patients were examined 13 years later by questionnaire, gynaecological examination, ultrasound examination of the urinary tract, and blood and urinary test concerning kidney function and diabetes mellitus., Results: Five patients had been re-operated within nine months because of contracture. In all patients (except one), the constructed vagina had good elasticity, width and depth. The donor area at the medial thigh was unaesthetic in four patients. No abnormalities were found in the urinary tract by ultrasound. One patients had a familial syndrome with Müllerian aplasia, progressive renal disease and mild diabetes mellitus. All patients found the operation important, despite memories of a painful postoperative period., Interpretation: This study shows functional and psychological satisfactory results of construction of vagina in women with vaginal agenesia.