Fetal growth restriction is among the most common and complex problems in modern obstetrics. Symphysis-fundus SF height measurement is a non-invasive test that may help determine which women are at risk.
This study is a systematic review of the literature on the accuracy of SF height measurement for the prediction of small-for-gestational-age SGA status at birth in unselected and low-risk pregnancies. The Medline, Embase, Cinahl, SweMed, and Cochrane Library databases were searched with no limitation on publication date through September , which returned citations.
Quality of the included studies was assessed in duplicate using criteria suggested by the Cochrane Collaboration. Review Manager 5. Eight studies were included in the final dataset and seven were included in summary analyses. Positive and negative likelihood ratios ranged from 1. SF height can serve as a clinical indicator along with other clinical findings, information about medical conditions, and previous obstetric history. Clinicians must understand the limitations of this test.
Peer Review reports. FGR is used to describe a fetus that did not reach its genetic growth potential and is associated with increased risks of morbidity and mortality, as well as adverse effects in childhood and later life [ 1 - 4 ]. Because no unanimously agreed-upon definition of FGR currently exists, small-for-gestational-age SGA is often used as a proxy. SGA is defined as weight below a specific percentile for gestational age, usually the 10th percentile. Although not all SGA neonates are pathologically growth restricted, detection of this group aims to facilitate the identification of at-risk pregnancies requiring further investigation due to potential FGR.
Early identification and appropriate management of FGR can reduce perinatal morbidity and mortality [ 5 ]. In Scandinavia, screening relies on routine measurement of SF height, complemented by ultrasound measurement of fetal size in women with pregnancy complications or with a relevant history or clinical evidence of FGR [ 6 - 8 ]. SF height is a technique involving measurement of the maternal abdomen from the symphysis pubis to the uterine fundus with a tape measure.
The measurement is plotted on a curve and compared with the distribution of the reference population [ 9 , 10 ]. If the recorded measurement is below acceptable limits according to the reference curves, further investigations of fetal growth and well-being are to be performed, including ultrasound estimations, uteroplacental and fetoplacental flow evaluations by Doppler, as well as cardiotocography.
Despite the routine use of SF height to predict SGA at birth, evidence for this method remains unclear. To date there is insufficient evidence from high quality trials to fully evaluate the effect of routine use of SF height during prenatal care on pregnancy outcomes [ 11 ]. Several studies have examined the accuracy of SF height in predicting SGA status at birth, but inconsistency in the results has been observed [ 12 ].
Most SF height research has been conducted in hospital-based settings and has investigated the relationship between SF height and SGA status in high risk populations [ 13 - 15 ]. Because of a different prevalence pre-test probability of SGA, results from hospital-based studies cannot be extrapolated to primary care settings.
In this systematic review we aim to assess the sensitivity and specificity of SF height for the prediction of SGA status at birth in unselected and low-risk pregnancies. Studies were selected for inclusion in the review according to the population, index test, target condition, reference standard, outcome measure, and study design. The search strategy was developed for PubMed and modified for use in other databases see Additional file 1. The reference lists of all included publications and relevant systematic reviews were checked and forward citation searches were performed.
The search strategy involved combinations of SF-related terms appearing in subject headings and as keywords. A list of articles meeting the inclusion criteria based on abstracts was compiled. The full texts of these studies and those of uncertain relevance were retrieved. Data were entered into a database using Review Manager 5. The QUADAS-2 checklist asks signaling questions in four risks of bias domains relating to patient selection, index test, reference standard, and flow and timing.
Each domain is assessed in terms of risk of bias, and the first three domains are also assessed in terms of applicability. Data on sensitivity, specificity, and true-positive, false-positive, true-negative, and false-negative results were taken directly from the source papers or, if necessary, calculated from the data provided.
An LR describes how many times more likely it is that a person with the target condition will receive a particular test result than will a person without it. Categorization of LRs was adopted from Deeks et al. The DOR is commonly used as an overall indicator of diagnostic performance and calculated as the odds of a positive test result among those with the target condition, divided by the odds of a positive test result among those without the condition.
The data were displayed graphically on forest and summary receiver operating characteristic SROC plots [ 22 ]. The SROC curve was fitted using the hierarchical bivariate random-effects method [ 23 ]. Both clinical and statistical heterogeneity were evaluated. Assessment of clinical heterogeneity involved comparison of SF reference curves, cut-off criteria used to identify abnormal results, and SGA definitions.
Assessment of statistical heterogeneity involved visual inspection of forest plots and calculation of the inconsistency index I 2 , which describes the percentage of total variation across studies that is due to heterogeneity, rather than chance [ 24 ]. Initial database searches retrieved citations of which citations remained after duplicates were removed Figure 1. Screening of the titles and abstracts identified 51 potentially relevant articles that were retrieved in full text format.
Forward and backward citation tracking did not result in the identification of additional relevant articles. Eight articles were included in final analyses. Additional file 3 lists the reasons for excluding 43 articles on the basis of study population, design or outcome measures. Characteristics of included studies [ 25 - 32 ] are presented in Table 1.
All studies were published before Most studies used locally derived SF curves. Based on the inclusion criteria, no included study had a case—control design. All studies avoided inappropriate exclusions. Six of the eight studies used consecutive or random recruitment of participants. The two remaining studies [ 30 , 32 ] did not report such information and were considered to be at unclear risk of patient selection bias.
Studies included in this review had a low risk of bias for the conduct of the reference standard. All studies used pre-specified index test thresholds. No study reported blinding to test results, but BW is objective and should not result in bias. Regarding the applicability of studies to the review questions, no study raised concern about the index test, reference standard or patient selection.
Tables 3 , 4 , 5 display core information collected from all included studies according to the SGA definition used by the study authors. Sensitivities ranged from 0. The SROC curve Figure 2 constructed using data from these studies lies to the left of the diagonal, signifying that the SF height test has value. Given the small number of included studies and thus low statistical power , subgroup analyses and covariate hierarchical modeling to investigate heterogeneity were not performed.
Summary receiving operating characteristic plot. This study used several cut-off points, with stricter criteria yielding lower sensitivity and higher specificity values. Adequate levels of sensitivity appear to be achieved at the expense of lower specificity, with higher numbers of false-positive SF results. The study of Rogers et al. Its false negative rate of only seven is likely to be due to the small size of the study.
In contrast, the study of Persson et al. Its sensitivity and specificity lies along the SROC line, adding weight to our findings. The diagnostic accuracy of SF height in other populations of pregnant women has recently been reviewed. Goto [ 33 ] assessed the diagnostic value of SF height, mainly in developing countries. However, this review included studies across a wide range of ethnic groups, clinical settings and disease spectrums. Despite such a diverse case mix, the study did not assess its effect on the pooled estimates, thus making it difficult to interpret its finding in a low-risk setting.
In view of these limitations, we applied more strict inclusion criteria in our study, focusing mainly on a more homogenous and relevant population.
The majority of studies available in this systematic review were conducted in the s. This measurement helps your provider estimate your baby's size, growth rate, and position during the second half of your pregnancy. As a rule of thumb, your fundal height in centimeters should roughly equal the number of weeks you're pregnant. For example, at 20 weeks, your fundal height should be about 17 to 23 centimeters.
Measuring large for gestational age means your fundal height is more than 3 centimeters larger than expected for your stage of pregnancy, based on your due date. Your provider will probably schedule an ultrasound to find out why. You could be measuring large for gestational age if:. Measuring small for gestational age means your fundal height is more than 3 centimeters smaller than expected for your stage of pregnancy.
Your provider may order an ultrasound to confirm your due date, in case you're not as far along as you thought. But if your baby doesn't appear to be growing as he should be, you'll have another ultrasound in about three weeks to check on his growth and the level of amniotic fluid. You also might need additional monitoring as your pregnancy progresses.
Measuring your fundal height is just one of the routine things your provider will do at your prenatal visits. Learn what else to expect at your visits and how to make the most of them. BabyCenter's editorial team is committed to providing the most helpful and trustworthy pregnancy and parenting information in the world.
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Washington, D. Practice bulletin Fetal growth restriction. American College of Obstetricians and Gynecologists. Method for estimating due date. Use of this site is subject to our terms of use and privacy policy.
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More About Fetal Development. View Sources. Aaron B. Caughey, M. Sarah Elizabeth Little, M. BJOG, Estimating gestational age at birth from fundal height and additional anthropometrics: a prospective cohort study , February March of Dimes, Oligohydramnios , June Mayo Clinic, Fetal Macrosomia , May Mayo Clinic, Fetal Ultrasound , January
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