First-trimester Crown-rump Length Research Articles

Reliability of trans-cerebellar diameter for gestational age in comparison to crown rump length

Background and objective: accurate estimation of gestational age is important for perfect antenatal care, as many pregnant women may don’t know their last menstrual period & not have a first-trimester ultrasound that is accurate in estimating the gestational age, and the routine fetal biometry in the second & third trimesters may be unreliable for some reason. Therefore, it’s necessary to develop an ultrasonographic parameter capable of reliably estimating gestational age at any point during pregnancy. This study aims to compare the accuracy of trans-cerebellar diameter (TCD) in n 2nd and 3rd trimesters for the calculation of estimated gestational age with the first-trimester crown rump length (CRL) which is the most accurate measurement for the estimation of gestational age. Methods: This is a prospective study conducted in Erbil from the 1st of January 2021 to the 10thof August 2022. A total sample of 258 antenatal women was included. The ultrasound examination was performed by a GE Voluson ultrasound system (GE health care 2015) machine using a 3.5 MHZ curved transducer. The CRL was taken between 6-13 weeks of gestational age, and TCD between 15-38 weeks. TCD is measured by keeping the calibers on the outer margin of the cerebellar hemisphere. Data were analyzed using the statistical package for social science SPSS V. 26. Results: The mean transcerebral diameter during different gestational ages was 16.35 (±0.76) less than 18 weeks gestation, 21.48 (±1.7) between 18-25 weeks gestation, 28.03 (±1.79) between 25-32 weeks gestation, 35.52 (± 1.84) above 32 weeks gestation respectively. There is a statistically significant linear correlation between TCD and ECRL with (rho=0.992) (P <0.001) Conclusion: The accuracy of the TCD in the second & third trimester of pregnancy is comparable with the estimated CRL in the first trimester, so this will help us in the estimation of the gestational age for pregnant women with unknown LMP and unavailable first-trimester dating scan.

The role of the ratio of first trimester CRL (crown rump length) measurement to NT (nuchal translucency) measurements in predicting early-onset fetal growth restriction (FGR)

Objective: Our aim is to evaluate the role of the ratio of first-trimester CRL (crown rump length) measurement to NT (nuchal translucency) measurements in predicting early-onset fetal growth restriction (FGR) and to contribute to the existing literature.
 Methods: In the present case-control study, fetuses with early-onset FGR were compared to a frequency matched low risk control group. This study was conducted in the perinatology clinic of Ankara Bilkent City Hospital between 2020 and 2023. Maternal age, gravidity, parity, crown-rump length (CRL), and nuchal translucency (NT) measurements were compared between pregnant women with early onset FGR (n=39) and pregnant women without FGR (n=50).
 Results: The mean age of pregnant women with FGR who participated in the study was 27.1±0.8, and the mean age of pregnant women without FGR was 26.3±0.6, and no statistically significant difference was found between the two groups (p=0.4)). Mean CRL was 54.98±1.08 mm in the group with FGR and 56.99±1.11 mm in the group without FGR; there was no significant difference between the two groups (p=0.2). The NT value was 1.11 ± 0.04 mm in the FGR group and 1.13 ± 0.02 mm in the without FGR group, there was no significant difference between the two groups (p=0.73). The mean CRL/NT ratio was 52.00±2.33 in the group with early onset FGR and 51.46±1.48 in the group without FGR and there was no statistically significant difference between the two groups (p=0.83).
 When the early developing FGR group is evaluated within itself, the mean age at diagnosis was 31.7±0.3 weeks. EFW mean percentile at diagnosis was 4.5±0.6 and ac percentile was 2.9±0.4. The mean umbilical artery systole/diastole ratio (UA-SD) was 2.9±0.16 and the mean umbilical artery pulsatility index (UA-PI) was 1.02±0.05.
 Conclusion: Crown-rump length to nuchal translucency ratio is not clinically useful to predict early-onset FGR.

Incidence of neonatal morbidity in small-for-gestational-age twins based on singleton and twin charts.

To compare morbidity, as measured by length of stay in the neonatal intensive care unit (NICU), in twin and singleton gestations classified as small-for-gestational age (SGA) according to estimated fetal weight < 10th percentile on twin or singleton growth charts. NICU length of stay was compared in 1150 twins and 29 035 singletons that underwent ultrasound assessment between 35 + 0 and 36 + 6 weeks' gestation. Estimated fetal weight was obtained from measurements of head circumference, abdominal circumference and femur length using the Hadlock formula. Gestational age was derived from the first-trimester crown-rump length measurement, using the larger of the two twins. Singletons and twins were compared in terms of NICU admission rate and length of stay according to classification as SGA by the Fetal Medicine Foundation singleton and twin reference distributions. The overall proportions of twins and singletons admitted to NICU were similar (7.3% vs 7.4%), but twins tended to have longer lengths of stay in NICU (≥ 7 days: 2.4% vs 0.8%; relative risk (RR), 3.0 (95% CI, 1.6-4.4)). Using the singleton chart, a higher proportion of twins were classified as SGA compared with singletons (37.6% vs 7.0%). However, the proportion of SGA neonates entering NICU was similar (10.2% for twins and 10.1% for singletons) and the proportion of SGA neonates spending ≥ 7 days in NICU was substantially higher for twins compared with singletons (3.7% vs 1.4%; RR, 2.6 (95% CI, 1.4-4.7)). When singleton charts are used to define SGA in twins and in singletons, there is a greater degree of growth-related neonatal morbidity amongst SGA twins compared with SGA singletons. Consequently, singleton charts do not inappropriately overdiagnose fetal growth restriction in twins and they should be used for monitoring fetal growth in both twins and singletons. © 2023 International Society of Ultrasound in Obstetrics and Gynecology.

The effect of cigarette smoking on first-trimester crown-rump length.

Does cigarette smoking impact the embryonic growth rate in the first trimester? This is a retrospective multicentre observational study of 2912 pregnancies. Women who presented to the early pregnancy and perinatal ultrasound units between 2010 and 2019 were included in the study. The data collected included the following: smoking status, the crown-rump length (CRL) of the pregnancy at the first ultrasound that showed an embryonic heart rate, the gestation in days and the CRL at another ultrasound up to the nuchal translucency scan and the gestation in days. Additional demographic data included the following: age, weight, height, parity and mode of delivery.Of the 2912, complete smoking and demographic data were available for 657 pregnancies. One hundred and thirty-seven (26.3%) were smokers, and 520 (73.7%) were not. The rate of change of smokers vs non-smokers between two CRLs and two different days of gestation was calculated. The Wilcoxon rank sum test with continuity correction was used for statistical analysis. This gives a value of W = 31,940 and a P-value = 0.06. There is a slight shift in location for the smokers; however, it is not statistically significant. The insignificance may be due to the general large variance in growth rate. The impact of cigarette smoking on embryonic growth rate detected by CRL in the first trimester is statistically insignificant.

Crown-rump length measurement error: impact on assessment of growth.

To examine the impact of first-trimester crown-rump length (CRL) measurement error on the interpretation of estimated fetal weight (EFW) and classification of fetuses as small-, large- or appropriate-for-gestational age on subsequent growth scans. We examined the effects of errors of ± 2, ± 3 and ± 4 mm in the measurement of fetal CRL on percentiles of EFW at 20, 32 and 36 weeks' gestation and classification as small-, large- or appropriate-for-gestational age. Published data on CRL measurement error were used to determine variation present in practice. A measurement error of -2 mm in first-trimester CRL shifts an EFW on the 10th percentile at the 20-week scan to around the 20th percentile, and the effect of a CRL measurement error of + 2 mm would shift an EFW on the 10th percentile to around the 5th percentile. At 32 weeks, a first-trimester CRL measurement error would shift an EFW on the 10th percentile to the 7th (+ 2 mm) or 14th (-2 mm) percentile; at 36 weeks, the EFW would shift from the 10th percentile to the 8th (+ 2 mm) or 12th (-2 mm) percentile. Published data suggest that measurement errors of 2 mm or more are common in practice. Because of the widespread and potentially severe consequences of CRL measurement errors as small as 2 mm on clinical assessment, patient management and research results, there is a need to increase awareness of the impact of CRL measurement error and to reduce measurement error variation through standardization and quality control. © 2021 International Society of Ultrasound in Obstetrics and Gynecology.

First-Trimester Crown-Rump Length (CRL) and Nuchal Translucency (NT) Discordance in Monochorionic Twins: An Ominous Sign or a Benign Feature?

This study aimed to evaluate the usefulness of the first-trimester crown-rump length (CRL) and nuchal translucency (NT) discordance in monochorionic diamniotic twins (MCDA) for the prediction of complications-twin-twin transfusion syndrome (TTTS), selective fetal growth restriction (sFGR) or intrauterine fetal demise (IUFD). Intertwin discordance in the CRL and NT was calculated as a percentage of the larger CRL and NT, respectively. The performance of inter twin discordance (CRL ≥ 10% and NT≥ 20%) for predicting complications was analysed using standard statistical screening test methods. Fifty-eight MCDA twin pregnancies were studied. Out of them, 19 (32%) pregnancies resulted in one of the complications studied (4 TTTS, 10 sFGR, 5 IUFD). CRL and NT discordance showed an increased probability of developing complications positive likelihood ratio (LR+) {95% confidence interval}: 2.05 {0.46-9.23} and 1.88 {1.03-3.45}, respectively. NT discordance showed a sensitivity of 57%. Although discordant first-trimester CRL and NT in monochorionic twins are poor screening tools for early prediction, if positive, they increase the risk of developing complications.

Pregnancy and perinatal outcomes of first-trimester crown-rump length discordant IVF dichorionic twin pregnancies - a retrospective cohort study.

This study aimed to evaluate the association between discordance in crown-rump length (CRL) and adverse pregnancy and perinatal outcomes in dichorionic twin pregnancies. This was a retrospective cohort study of dichorionic twin pregnancies after IVF that showed two live fetuses at the first ultrasound scan between 6 +5 and 8 weeks gestational age from 1 January 2015 to 31 December 2016. Study groups were defined by the presence or absence of 20% or more discordance in CRL. The primary outcomes were early fetal loss of one or both fetuses before 12 weeks and birthweight discordance. Secondary outcomes included fetal anomalies, fetal loss between 12 and 28 weeks, stillbirth, small for gestational age (SGA) at birth, low birthweight (LBW), very low birthweight (VLBW), admission to the neonatal intensive care unit (NICU) and preterm delivery (PTD). CRL-discordant twin pregnancies were more likely to end in the loss of one fetus before 12 weeks' gestation (odds ratio [OR] 15.877, 95% confidence interval [CI] 10.495-24.019). Discordant twin pregnancies with twin deliveries had a significantly higher risk of birthweight discordance (OR 1.943, 95% CI 1.032-3.989). There was no significant difference in perinatal outcomes including fetal anomalies, PTD, LBW, VLBW, SGA, neonatal death and admission to NICU between singleton or twin deliveries. Discordant twin pregnancies were at increased risk of one fetal loss prior to 12 weeks' gestation. Except for birthweight discordance, there was no significant difference between CRL discordance and other adverse perinatal outcomes.

Pregnancy and perinatal outcomes of first-trimester crown-rump length discordance in dichorionic twin pregnancies after in vitro fertilization

To evaluate the association between first- trimester crown-rump length discordance and adverse pregnancy and perinatal outcomes in dichorionic twin pregnancies. This was a retrospective cohort study of women with dichorionic twin pregnancies after in vitro fertilization (IVF) at our fertility center with two live fetus scanned between 6+5 and 8 weeks’ gestation during the period 1st January 2015 and 1st January 2017. Study groups were defined by the presence or absence of ≥20% crown-rump length (CRL) discordance at the first-trimester ultrasound scans. Pregnancy outcomes including spontaneous abortion, stillbirth and live birth were compared between discordant and concordant twin pregnancies. Perinatal outcomes (preterm delivery, [PTD], low birth weight [LBW], very low birth weight [VLBW], birthweight discordant, neonatal death and admission in neonate intensive care unit [NICU]) were also assessed. Singleton live deliveries and twin deliveries were analyzed separately. Moreover, fetal anomalies were also evaluated. During the study period we identified 1687 dichorionic twin pregnancies on first-trimester ultrasound, of which1504 met the inclusion criteria. Of the 1504 dichorionic twin pregnancies included, 129 (8.58%) patients were identified as having CRL discordance of at least 20%. CRL discordant twin were more likely to end in one fetal loss before 12 weeks’ gestation (Relative risk= 15.073,95% confidence interval, 10.128-22.431) than were concordant dichrionic twin pregnancies. Discordant twin pregnancies with twin deliveries were at significant higher risk of birthweight discordance (Relative risk=2.192,95% confidence interval, 1.054-4.558). There was no significant difference in perinatal outcomes including PTD, LBW, VLBW, neonatal death and admission to NICU in singleton or twin deliveries. No fetal anomalies were observed in discordant twin pregnancies. Dichorionic twin pregnancies were at increased risk for one fetal loss prior to 12 weeks’ gestation and birthweight discordance, but were not associated with adverse perinatal outcomes and fetal anomalies.

First-Trimester Crown-Rump Length and Risk of Chromosomal Aberrations-A Systematic Review and Meta-analysis.

Lower than expected first-trimester crown-rump length (CRL) is a common sonographic finding, usually leading to reassessment of gestational age. The aim of this study was to perform a meta-analysis defining the risk of chromosomal aberrations in pregnancies with decreased first-trimester CRL. A search was conducted by a research librarian in 5 databases, with no time or language restrictions. Original researches examining the risk of chromosomal aberrations in pregnancies with low CRL were selected. The effect estimates were presented as odds ratios with 95% confidence intervals). Following screening of 3894 references, 12 articles were selected. Only 2 articles directly fulfilled the review goals, comparing the rates of chromosomal aberrations in small-CRL versus normal-CRL fetuses. Combined analysis of these 2 studies, encompassing a total of 403 fetuses with small CRL and 4047 control pregnancies, yielded an odds ratio of 5.54 (95% confidence interval, 1.2-26.1) for abnormal karyotype in small-CRL fetuses. Ten studies compared CRL in fetuses with specific chromosomal aberrations to pregnancies with normal karyotype, yielding a significant growth delay in fetuses with trisomy 18 (6 of 7 articles) and triploidy, but not in fetuses with trisomy 21. Overall quality of evidence was rated as "very low" using Grading of Recommendations Assessment, Development and Evaluation criteria. Our review results indicate that low first-trimester CRL might be associated with a significantly increased risk of chromosomal anomalies. Thus, invasive prenatal testing or cell-free DNA screening might be offered in such pregnancies, particularly if dating is certain.

Do Early Fetal Measurements and Nuchal Translucency Correlate With Term Birth Weight?

Traditionally, physiological variation in fetal weight is believed to emerge during the latter half of pregnancy. Although recent evidence suggests that crown-rump length (CRL) and nuchal translucency (NT) measured at 11-14 weeks correlate with abnormal fetal growth, findings have been limited by dating accuracy in spontaneous gestations. Therefore, we sought to determine whether CRL or NT measurements correlated with term birth weight (BW) or BW ratio in a cohort of IVF pregnancies, in which the date of conception is precisely known. This retrospective cohort study included 227 term, singleton IVF pregnancies. Subjects were included if they had an early first-trimester ultrasound examination and subsequent nuchal translucency (NT) screening. The difference between the measured and the expected CRL and the biparietal diameter (BPD) and NT measurement were calculated and correlated with the actual term BW or BW ratio. The BW ratio was calculated using the actual BW and the expected BW for GA. The difference between measured and expected mid-first-trimester CRL, and the BPD at NT assessment, correlated with BW ratio at delivery (rSpearman= 0.15, P= 0.023 and rSpearman= 0.27, P< 0.001, respectively). Absolute NT measurements and NT percentiles (adjusted for CRL) correlated with BW ratio at delivery (rSpearman= 0.18, r= 0.14, and P= 0.005 and 0.038, respectively). In this well-dated IVF population, we report a significant correlation between BW ratio and first-trimester CRL, BPD, and NT measurements. These findings support the hypothesis that physiological variation in BW can be reflected by variation in first-trimester fetal measurements.

Prediction of fetal loss by first-trimester crown-rump length in IVF pregnancies.

To evaluate the association between small crown-rump length (CRL) and fetal loss ≤22weeks in IVF pregnancies. A retrospective analysis of prospectively collected data at a university-affiliated medical center. All singleton IVF pregnancies within a 5-year period, with a live embryo on first-trimester ultrasound and verified pregnancy outcome were included. Rates of fetal loss ≤22weeks were compared between pregnancies with a CRL ≤tenth percentile and above the tenth percentile of our population. Overall, 397 pregnancies met inclusion criteria. Ninety-five percent of CRL measurements were performed at 40-80 gestational days. All live-embryo's CRL measurements, from 40 to 80mm, were plotted against expected gestational age (in 5-day clusters), with calculation of the tenth percentile for every gestational age. Total of 64 pregnancies had CRL ≤tenth percentile for gestational age. The rate of fetal loss in this group was significantly higher than in pregnancies with CRL >tenth percentile (17.2 vs. 6.6%, p=0.005, OR=2.93, 95% CI 1.2-6.7). In both groups, the majority of fetal losses occurred ≤10weeks of gestation. In IVF pregnancies with a live embryo, a small CRL at 40-80days' gestation may predict fetal loss. Repeated ultrasound should be considered after 1-2weeks.

Periconceptional maternal biomarkers of one-carbon metabolism and embryonic growth trajectories: the Rotterdam Periconceptional Cohort (Predict Study)

To study the associations between the periconceptional maternal biomarkers of one-carbon metabolism and embryonic growth. Prospective, periconceptional hospital-based birth cohort. Tertiary medical care center. Between 2010 and 2014, 236 women with early singleton ongoing pregnancies that resulted in 139 strictly dated spontaneous pregnancies and 97 pregnancies conceived after assisted reproductive technology. None. Maternal serum vitamin B12 and plasma total homocysteine (tHcy) assessed at enrollment, and longitudinal first-trimester crown-rump length (CRL), embryonic volume (EV), and absolute growth rates obtained via three-dimensional ultrasound (3D-US) and virtual reality. In early pregnancy, we performed a median of five 3D-US scans (range: 1-7). Vitamin B12 concentrations were positively associated with CRL and EV measurements in the total population (CRL: β 5ˆ10-4 (1ˆ10-4 to 9ˆ10-4) √mm; EV: β 2ˆ10-4 (0ˆ10-4 to 4ˆ10-4) 3√cm3) and in the strictly dated spontaneous pregnancy subgroup. The tHcy concentration was negatively associated with embryonic growth in all study groups. High tHcy concentrations (+2 standard deviation [SD], 10.3μmol/L) were associated with a 1.7mm smaller CRL (-13.4%) at 7weeks and a 3.6-mm smaller CRL (-7.1%) at 11weeks compared with -2 SD tHcy (-3.0μmol/L). A high tHcy concentration was also associated with a 0.10cm3 smaller EV (-33.3%) at 7weeks and a 1.65cm3 smaller EV (-16.1%) at 11weeks. The embryonic growth rate was positively associated with vitamin B12 and negatively associated with tHcy. Minor variations in periconceptional maternal concentrations of one-carbon metabolism biomarkers are associated with human embryonic growth.

Fetal cardiovascular remodeling persists at 6 months in infants with intrauterine growth restriction.

Intrauterine growth restriction is associated with increased cardiovascular risk later in life but the link between fetal disease and postnatal risk is not well-documented. We evaluated longitudinally the association between cardiovascular remodeling in small-for-gestational-age (SGA) fetuses and at 6 months of age. A cohort of 80 SGA fetuses (defined by estimated fetal and birth weights < 10(th) centile) delivered > 34 weeks' gestation was compared with 80 normally grown age-matched control fetuses, with follow-up at 6 months of corrected age (i.e. 6 months from estimated date of delivery according to first-trimester crown-rump length). Cardiovascular evaluation included a comprehensive echocardiographic assessment in both fetuses and infants and blood pressure and aortic intima-media thickness (aIMT) measurement in infants. Parameters were adjusted by linear regression analysis for gender, gestational age at delivery, pre-eclampsia, prenatal glucocorticoid exposure, Cesarean delivery, admission to neonatal intensive care unit and body surface area. Both pre- and postnatally, when compared with controls, the SGA group showed a more globular cardiac shape (left sphericity index: controls 2.06 vs SGA 1.87 (P = 0.022) prenatally and 1.92 vs 1.67 (P = 0.007) postnatally), as well as signs of systolic longitudinal dysfunction (systolic annular peak velocity (S'): 7.2 vs 6.3 cm/s (P = 0.003) prenatally and 7.9 vs 6.4 cm/s (P < 0.001) postnatally; tricuspid annular plane systolic excursion: 7.2 vs 6.8 mm (P = 0.015) prenatally and 16.0 vs 14.2 mm (P < 0.001) postnatally) and diastolic dysfunction (left isovolumetric relaxation time: 46 vs 52 ms (P < 0.001) prenatally and 50 vs 57 ms (P = 0.034) postnatally). In addition, infants in the SGA group had increased mean blood pressure (mean: 61 vs 70 mmHg, P < 0.001) and maximum aIMT (0.57 vs 0.66 mm; P < 0.001). Primary cardiovascular changes are already present in the SGA fetus and persist at 6 months of age. These data support prenatal cardiovascular remodeling as a mechanistic pathway of increased risk later in life in cases of SGA, regardless of Doppler abnormalities. Copyright © 2015 ISUOG. Published by John Wiley & Sons Ltd.

Intertwin crown-rump length discordance in the prediction of fetal anomalies, fetal loss and adverse perinatal outcome

Objective: To assess the risks of fetal anomalies, fetal loss and adverse perinatal outcome in a cohort of first-trimester intertwin crown-rump length (CRL) discordant twins, stratified by chorionicity and the degree of CRL discordance. Method: Four-hundred-and-seventy-one twin pregnancies were scanned during an 8-year period at 11–14 weeks, and those with an intertwin CRL discordance ≥10% were compared with concordant twins. Outcomes were also compared between monochorionic and dichorionic twins and between moderate (10–16%) and severe (>16%) discordance. Results: Four-hundred-and-five twin pregnancies, 65 discordant and 340 concordant, were follow-up. Discordant twin pregnancies were at significant higher risk of chromosomal (OR = 11.42; 95% CI: 2.78–46.94) and structural anomalies (OR = 5.91; 95% CI: 2.25–15.54), spontaneous fetal loss (OR = 4.23; 95% CI: 1.79–10.01), birthweight discordance (OR = 2.8; 95% CI: 1.48–5.65) and small-for-gestational age (OR = 3.48; 95% CI: 1.78–6.79). Similar differences (except for birthweight discordance) were observed among dichorionic twins. Among monochorionic, increased frequencies were only seen for structural anomalies, birthweight discordance and small newborns. Severe CRL discordance presented with higher rates of structural anomalies, stillbirth, birthweight discordance and small newborns. Conclusion: Intertwin CRL discordance (≥10%) results in an increased risk of fetal anomalies and growth restriction that increases in severe CRL discordance (≥16%).

First-trimester crown-rump length affects birth size symmetrically

Objective: To investigate the relationship between crown-rump length (CRL) and birth weight, length and head circumference of the newborn.Methods: From a database of delivery records of 12 000 pregnancies, we identified 999 women with singleton pregnancies who had no medical problems, a normal menstrual history and a first trimester ultrasound scan in which CRL had been measured. All of the pregnancies resulted in live births without evidence of chromosomal and congenital abnormalities. The population in this study was divided into three groups according to CRL measurement; Group A (smaller-than-expected CRL), Group B (normal CRL) and Group C (larger-than-expected CRL).Results: The incidence of low birth weight infant was higher in Group A than in Group C (p = 0.010). The rate of small for gestational age (SGA) infants was similar between groups. The number of macrosomic or large for gestational age (LGA) infants was higher in Group C than Groups A and B. Both birth head circumference and length of infant were greater in Group C than Groups A and B. No significant difference for ponderal index value was observed between the groups (p = 0.927).Conclusion: The growth pattern in the first trimester affects neonatal birth weight and length symmetrically without changing the ponderal index.

The influence of IVF/ICSI treatment on human embryonic growth trajectories.

Is in vitro fertilization treatment with or without intracytoplasmatic sperm injection (IVF/ICSI) associated with changes in first and second trimester embryonic and fetal growth trajectories and birthweight in singleton pregnancies? Embryonic and fetal growth trajectories and birthweight are not significantly different between pregnancies conceived with IVF/ICSI treatment and spontaneously conceived pregnancies with reliable pregnancy dating. IVF/ICSI treatment has been associated with increased risks of preterm birth, fetal growth restriction and low birthweight. Decreased first-trimester crown-rump length (CRL) in the general population has been inversely associated with the same adverse pregnancy outcomes. In a prospective periconception birth cohort study conducted in a tertiary centre, 146 singleton pregnancies with reliable pregnancy dating and nonmalformed live borns were investigated, comprised of 88 spontaneous and 58 IVF/ICSI pregnancies. Serial 3D ultrasound scans were performed from 6 to 12 weeks of gestation. As estimates of embryonic growth, CRL and embryonic volume (EV) were measured using the I-Space virtual reality system. General characteristics were obtained from self-administered questionnaires at enrolment. Fetal growth parameters at 20 weeks and birthweight were obtained from medical records. To assess associations between IVF/ICSI and embryonic growth trajectories, estimated fetal weight and birthweight, stepwise linear mixed model analyses and linear regression analyses were performed using square root transformed CRL and fourth root transformed EV. In 146 pregnancies, 934 ultrasound scans were performed of which 849 (90.9%) CRLs and 549 (58.8%) EVs could be measured. Embryonic growth trajectories were comparable between IVF/ICSI pregnancies and spontaneously conceived pregnancies (CRL: βIVF/ICSI = 0.10√mm; P = 0.10; EV: βIVF/ICSI = 0.03(4)√cm³; P = 0.13). Estimated fetal weight and birthweight were also comparable between both groups (βIVF/ICSI = 6 g; P = 0.36 and βIVF/ICSI = 80 g; P = 0.24, respectively). Variations in embryonic growth trajectories of spontaneously conceived pregnancies with reliable pregnancy dating may partially be a result of less precise pregnancy dating and differences in endometrium receptivity compared with IVF/ICSI pregnancies. The absence of a significant difference in embryonic and fetal growth trajectories suggests safety of IVF/ICSI treatment with regard to early embryonic growth. However, further research is warranted to ascertain the influence of IVF/ICSI treatments in a larger study population, and to estimate the impact of the underlying causes of the subfertility and other periconceptional exposures on human embryonic and fetal growth trajectories. This study was supported by the Department of Obstetrics and Gynaecology of the Erasmus MC, University Medical Centre. No competing interests are declared.

First-trimester fetal growth discordance and development of preeclampsia in dichorionic twin pregnancies

To investigate the relation between first-trimester fetal growth discrepancy, as assessed by crown-rump length (CRL) at 11+0 to 13+6 weeks of gestation, and subsequent development of preeclampsia (PE) in dichorionic diamniotic (DCDA) twin pregnancies. The association between inter-twin CRL and birth weight (BW) discrepancy was also investigated. This was a retrospective, case-control study of DCDA twin pregnancies. Inter-twin CRL discrepancy was calculated as 100×(larger CRL-smaller CRL)/larger CRL. BW discordance was calculated as 100×(larger BW-smaller BW)/larger BW. The study included 299 DCDA pregnancies that remained normotensive and 35 that subsequently developed PE. There was no significant difference in the inter-twin CRL discrepancy between pregnancies complicated by PE and those that were not [3.2%, interquartile range (IQR): 0.5-4.5% vs. 3.3%, IQR: 1.4-5.5%; P=0.17]. There was a positive correlation between inter-twin CRL and BW discrepancy but only in pregnancies that remained normotensive (P<0.001). In women that subsequently developed PE, there was no association between inter-twin CRL and BW discordance (P=0.54). In unselected DCDA twins, first-trimester CRL discrepancy is not different between pregnancies that subsequently develop PE and those that remain normotensive. Furthermore, in pregnancies that are complicated by PE, the association between inter-twin CRL and BW discrepancy appears to be lost.

Tracking of fetal growth characteristics during different trimesters and the risks of adverse birth outcomes

Fetal growth characteristics are used to identify influences of several maternal characteristics and to identify individuals at increased risk of adverse outcomes. The extent to which fetal growth characteristics track in different trimesters is not known. In a population-based prospective cohort study among 8636 pregnant women, we examined the extent to which fetal growth characteristics track, are influenced by maternal socio-demographic and lifestyle related determinants and are associated with birth outcomes. Fetal growth was assessed in each trimester and at birth. Correlation coefficient between first-trimester crown-rump length and birthweight was r = 0.12 (P-value < 0.05). Correlation coefficients for fetal-head circumference, (femur) length and (estimated) fetal weight ranged from r = 0.16 to r = 0.30 (all P-values < 0.05) between second trimester and birth and from r = 0.36 to r = 0.58 (all P-values < 0.05) between third trimester and birth, and were highest for (estimated) fetal weight. Correlation coefficients for (estimated) fetal weight tended to be lower among overweight mothers, as compared with normal weight mothers, but were not influenced by other maternal characteristics. First, second and third-trimester fetal growth characteristics were associated with risks of preterm birth and small size for gestational age at birth,with the strongest associations present in third trimester. Fetal growth characteristics track moderately throughout gestation, with stronger tracking coefficients present in later pregnancy. Tracking coefficients were not materially influenced by maternal socio-demographic and lifestyle characteristics. First, second and third trimester fetal growth characteristics were associated with the risk of adverse birth outcomes.

An optimal periconception maternal folate status for embryonic size: the Rotterdam Predict study

To investigate the association between periconception maternal folate status and embryonic size. Prospective periconception cohort study. Erasmus University Medical Centre, Rotterdam, the Netherlands. Seventy-seven singleton pregnancies recruited in 2009 and 2010. We recruited women before 8 weeks of gestation and performed weekly three-dimensional ultrasound scans from enrolment up to 13 weeks of gestation. As a measure of embryonic growth, crown-rump length (CRL) measurements were performed using V-Scope software in the BARCO I-Space. Maternal blood was collected to determine first-trimester long-term red blood cell (RBC) folate status. Non-malformed live births were included in the analysis. We calculated quartiles of RBC folate, square root-transformed CRL data and performed multivariable linear mixed model analyses. Serial first-trimester CRL measurements. In total, 484 ultrasound scans were performed in 77 women, in 440 (90.7%) of which CRLs could be measured. RBC folate in the third quartile (1513-1812 nmol/l) was significantly associated with an increased CRL compared with the first two quartiles (814-1512 nmol/l) and the upper quartile (1813-2936 nmol/l; P(overall) = 0.03; adjusted for gestational age, smoking, body mass index and fetal sex). Compared with the third quartile, embryos in the upper quartile were 24.2% smaller at 6(+0) weeks [4.1 mm (95% confidence interval 3.5, 4.7) versus 5.4 mm (95% confidence interval 4.8, 6.1)] and 7.6% smaller at 12(+0) weeks [55.1 mm (95% confidence interval 52.9, 57.3) versus 59.6 mm (95% confidence interval 57.4, 62.0)] of gestation. This study suggests that a very high maternal periconception folate status is associated with reduced embryonic size. Whether these effects are beneficial or harmful requires further investigation.

358: Predicting infant and placental weight at birth (PLWB) using customized models including first-trimester 3D placental volume, crown-rump length (CRL) and maternal characteristics

358: Predicting infant and placental weight at birth (PLWB) using customized models including first-trimester 3D placental volume, crown-rump length (CRL) and maternal characteristics