Is first‐trimester crown–rump length associated with birthweight?

Abstract

We wish to thank Dr Tiran Dias and Professor Basky Thilaganathan 1 for their comments on our recent publication about the association between crown-rump length (CRL) and birthweight. 2 They comment on our method to date pregnancies following in vitro fertilisation (IVF). Indeed, gestational age (GA) was calculated by adding 14 days to the number of days between the date of oocyte retrieval and the date of ultrasound examination. This seems an appropriate method because fertilisation was performed on the day of oocyte retrieval in all women. Moreover, this method remains reliable whatever the timing of embryo or blastocyst transfer later on. Moreover, we must emphasise that there were no ovum donations or frozen embryos in our cohort.Second, and more importantly, they hypothesise that such misdating, rather than early variation in fetal growth, could create an artificial association between early and late growth. This has already been suggested by Smith. 3 To prevent such spurious associations, they suggest that we should look at the association with bodyweight once pregnancies have been dated by the CRL measurement. This is a good point but was already performed in our study, as stated in the second paragraph of the Results section 'This relationship persisted when GA was calculated from CRL (b = 0.13, P = 0.02)'.We understand that our work challenges the traditional view stating that physiological variations in fetal size emerge during the latter half of pregnancy. However, we believe that our data add to a growing body of evidence that complications of late pregnancy, such as abnormal growth, may be the ultimate consequence of conditions that have their origins in the very earliest weeks of gestation and precede the first ultrasound examination. j For the first time our report also included an assessment of whether or not the perinatal deaths were considered to have been potentially avoidable. We have also recently published our system for classifying contributory factors and potential avoidability for 4 years of data on maternal deaths (49 deaths in total). 4 Our classification differs from other approaches as it includes barriers to accessing and engaging in care, as well as management and organisational issues, personnel issues, geography and environmental factors. The maternal deaths were assessed by a central working party of the PMMRC, whereas the 721 perinatal deaths were assessed by local teams of clinicians, which typically included senior midwives, obstetricians and neonatologists or paediatricians. We are currently undertaking further research to validate this classification system by comparing local review with an expert review panel. Using this approach we found that onethird of maternal deaths and 14% of perinatal deaths (15% of stillbirths) were potentially avoidable. The most common categories of contributory factors found in both maternal and perinatal death reviews were barriers to accessing and engaging in maternity care, and lack of knowledge and skills among personnel. We can now direct...

Correlation of first‐trimester fetal crown–rump length with outcome of pregnancy and birth weight

“…The accurate estimation of fetal weight, size, growth rate, and gestational age can lead to the diagnosis of several perinatal conditions, and therefore have an important role in reducing perinatal morbidity and mortality [3]. Since growth patterns in the first trimester are among the chief factors determining birth weight, a fetus small for gestational age in the first trimester will still be small for gestational age at delivery [4,5].…”

Efficiency of first‐trimester growth restriction and low pregnancy‐associated plasma protein‐A in predicting small for gestational age at delivery

“…Smith et al has shown that a first‐trimester crown–rump length (CRL) that is 2 to 6 days smaller than expected is associated with an increased risk for low birthweight (LBW) and SGA. This association was also seen both prospectively and retrospectively in women who conceived as a result of assisted reproductive technology (ART) . Most recently Mook‐Kanamori et al confirmed an increase risk of LBW and delivery of an SGA infant in the setting of first trimester fetal growth restriction.…”

Birth weight and cognition in children with epilepsy

“…For example, Graca et al 28 examined cerebral volumes during the first postnatal week in 128 infants and found that brain volumes are highly correlated with birth weight. Furthermore, fetal growth as documented by ultrasound during the first 29 and second 30 trimesters has been shown to influence postnatal birth weight. Given the important association between prenatal brain development and postnatal birth weight, our findings of modest birth weight reduction in CWE may provide the earliest indicator for the origin of abnormal neurodevelopment.…”