Crown-Rump Length

ImportanceThe American Academy of Pediatrics currently recommends weight for length (WFL) for assessment of weight status in children younger than 2 years but body mass index (BMI) for children older than 2 years. However, the clinical implications of using WFL vs BMI in children younger than 2 years as an indicator of future health outcomes remains understudied.ObjectiveTo compare associations of overweight based on WFL vs BMI in children younger than 2 years with cardiometabolic outcomes during early adolescence.Design, setting, and participantsThis prospective study of birth cohorts in the United States (Project Viva) and Belarus (Promotion of Breastfeeding Intervention Trial [PROBIT]) performed from June 1, 1996, to November 31, 2002, included 13 666 children younger than 2 years.Main exposuresOverweight defined as Centers for Disease Control and Prevention (CDC) WFL in the 95th percentile or greater, World Health Organization (WHO) WFL in the 97.7th percentile or greater, or WHO BMI in the 97.7th percentile or greater at 6, 12, 18, or 24 months of age.Main outcomes and measuresPrimary outcomes were fat mass index, insulin resistance, metabolic risk score, and obesity during early adolescence. Secondary outcomes were height and BMI z scores, sum of skinfolds, waist circumference, and systolic blood pressure during early adolescence.ResultsThe study included 919 children (mean [SD] age, 12.9 [0.9] years; 460 [50.1%] male; and 598 [65.1%] white) from Project Viva and 12 747 children (mean [SD] age, 11.5 [0.5] years; 6204 [48.7%] male; and 12 747 [100%] white) from PROBIT. During 6 to 24 months of age, in Project Viva, 206 children (22.4%) were overweight at any of the 4 times points according to the CDC WFL, 160 (17.4%) according to WHO WFL, and 161 (17.5%) according to WHO BMI cut points. In PROBIT, 3715 children (29.1%) were overweight at any of the 4 time points according to the CDC WFL, 3069 (24.1%) according to WHO WFL, and 3125 (24.5%) according to WHO BMI cut points. After maternal and child characteristics were adjusted for, being ever overweight (vs never overweight) during 6 to 24 months of age was associated with higher likelihood of adverse cardiometabolic risk markers during early adolescence, but associations did not differ substantially across WFL and BMI cut points in either cohort. For example, for fat mass index in Project Viva, β = 0.9 (95% CI, 0.5-1.4) for the CDC WFL, β = 1.1 (95% CI, 0.6-1.6) for WHO WFL, and β = 1.4 (95% CI, 0.9-1.9) for WHO BMI. For PROBIT, β = 0.5 (95% CI, 0.4-0.6) for the CDC WFL, β = 0.6 (95% CI, 0.5-0.7) for WHO WFL, and β = 0.6 (95% CI, 0.5-0.6) for WHO BMI. Neither growth metric in infancy was superior over the others based on F statistics (Project Viva: 17.1-17.8; PROBIT: 87.1-88.7). Findings were similar for insulin resistance, metabolic risk score, obesity, and secondary outcomes.Conclusions and relevanceChoice of WFL vs BMI to define overweight during the first 2 years of life may not greatly affect the association with cardiometabolic outcomes during early adolescence. The findings appear to have important implications for investigators seeking to use BMI as a growth metric for epidemiologic research and for practitioners monitoring the weight status of children younger than 2 years.

BackgroundFetal ultrasound scanning is considered vital for routine antenatal care with first trimester scans recommended for accurate estimation of gestational age (GA). A reliable estimate of gestational age is key information underpinning clinical care and allows estimation of expected date of delivery. Fetal crown-rump length (CRL) is recommended over last menstrual period for estimating GA when measured in early pregnancy i.e. 9+0-13+6 weeks.MethodsThe INTERGROWTH-21st Project is the largest prospective study to collect data on CRL in geographically diverse populations and with a high level of quality control measures in place. We aim to develop a new gestational age estimation equation based on the crown-rump length (CRL) from women recruited between 9+0-13+6 weeks. The main statistical challenge is modelling data when the outcome variable (GA) is truncated at both ends, i.e. at 9 and 14 weeks.We explored three alternative statistical approaches to overcome the truncation of GA. To evaluate these strategies we generated a data set with no truncation of GA that was similar to the INTERGROWTH-21st Project CRL data, which we used to explore the performance of different methods of analysis of these data when we imposed truncation at 9 and 14 weeks of gestation. These 3 methods were first tested in a simulation based study using a previously published dating equation by Verburg et al. and evaluated how well each of them performed in relation to the model from which the data were generated. After evaluating the 3 approaches using simulated data based on the Verburg equations, the best approach will be applied to the INTERGROWTH-21st Project data to estimate GA from CRL.ResultsResults of these rather "ad hoc" statistical methods correspond very closely to the "real data" for Verburg, a data set that is similar to the INTERGROWTH-21st project CRL data set.ConclusionsWe are confident that we can use these approaches to get reliable estimates based on INTERGROWTH-21st Project CRL data. These approaches may be a solution to other truncation problems involving similar data though their application to other settings would need to be evaluated.

Study questionIs early embryonic size and growth in the first trimester of pregnancy associated with adverse birth outcomes?Summary answerLarger embryonic crown-rump length (CRL) and embryonic volume (EV) are associated with lower odds of adverse birth outcomes, especially small for gestational age (SGA).What is already knownPreterm birth, SGA, and congenital anomalies are the most prevalent adverse birth outcomes with lifelong health consequences as well as high medical and societal costs. In the late first and second trimesters of pregnancy, fetuses at risk for adverse birth outcomes can be identified using 2-dimensional ultrasonography (US).Study design, size, durationBetween 2009 and 2018, singleton pregnancies were enrolled in this ongoing prospective Rotterdam Periconception Cohort.Participants/materials, setting, methodsThis study included 918 pregnant women from a tertiary hospital in the Netherlands. Pregnancy dating was based on either a regular menstrual cycle (for natural pregnancies) or a conception date (for ART pregnancies). CRL and EV were measured using Virtual Reality software on 3-dimensional (3D) ultrasound scans, repeatedly performed around 7, 9, and 11 weeks of gestation. The main outcome measure was adverse birth outcome, defined as the composite of SGA (birth weight 16th week of pregnancy), or early neonatal mortality (≤7 days of life). Reference curves for CRL and EV were constructed. Cross-sectional (CRL/EV Main results and the role of chanceOf the 918 pregnant women included, the median age was 32.3 years, and 404 (44%) pregnancies had been conceived via ART. In 199 (22%) pregnancies, there was an adverse birth outcome. Regression analyses showed that at 7 weeks of gestation onwards, embryos with a CRL Limitations, reasons for cautionThe tertiary hospital population and the availability of sophisticated 3D-ultrasound techniques limit the generalizability of this study to general populations and settings.Wider implications of the findingsAlready very early in the first trimester of pregnancy, embryos with increased risks of an adverse birth outcome can be identified by using 3D-US and Virtual Reality. This expands the window of opportunity to enable the development of future interventions to potentially improve pregnancy outcomes and offspring health during their life-course.Study funding/competing interest(s)This work was funded by the Department of Obstetrics and Gynecology, Erasmus MC, University Medical Centre, Rotterdam, The Netherlands. The authors declare no conflicts of interest.Trial registration numberNL4115.

BackgroundExposure to heat and cold are associated with adverse birth outcomes, but whether ambient temperature affects embryonic and early fetal development remains unclear. We aimed to examine the association between ambient temperature exposure during early pregnancy and crown-rump length (CRL).MethodsData from the Generation R Next Study (2017-2021) were analysed, with findings replicated in the Generation R Study (2002-2006), both population-based cohorts based in Rotterdam, The Netherlands. Weekly mean temperatures were modeled from the last menstrual period onward at a spatial resolution of 100 × 100 m by using the UrbClim™ model. The CRL was measured via 2D ultrasound at approximately 8, 10, and 12 weeks' gestation in pregnancies with regular menstrual cycles. Distributed lag nonlinear models were applied.ResultsIn Generation R Next (N = 1378; mean maternal age 31.9 years), higher temperatures during the first 9 weeks were associated with a smaller CRL at 12 weeks {e.g. -7.2 mm [95% confidence interval (CI) -12.0, -2.3] at 19.2 vs 9.0°C during weeks 1-6}. Colder exposures during the first 11 weeks were also associated with a smaller CRL [-7.6 mm (95% CI -11.9, -3.3) at 3.6 vs 9.0°C during weeks 1-11]. No associations were observed for CRL at 8 or 10 weeks. Similar associations with cold, but not heat, were observed in the replication cohort (N = 1520).ConclusionModerate cold and heat exposure during early pregnancy may affect fetal development as early as the first trimester. These findings indicate that early gestational development may be sensitive to ambient temperature and, as environmental conditions shift, may have potential clinical implications for birth outcomes and long-term health.