Intrauterine growth retardation

Measurement of symphysis fundal height for gestational age estimation in low-to-middle-income countries: A systematic review and meta-analysis

In low- and middle-income countries (LMIC), measurement of symphysis fundal height (SFH) is often the only available method of estimating gestational age (GA) in pregnancy. This systematic review aims to summarize methods of SFH measurement and assess the accuracy of SFH for the purpose of GA estimation. We searched PubMed, EMBASE, Cochrane, Web of Science, POPLINE, and WHO Global Health Libraries from January 1980 through November 2021. For SFH accuracy, we pooled the variance of the mean difference between GA confirmed by ultrasound versus SFH. Of 1,003 studies identified, 37 studies were included. Nineteen different SFH measurement techniques and 13 SFH-to-GA conversion methods were identified. In pooled analysis of five studies (n = 5838 pregnancies), 71% (95% CI: 66-77%) of pregnancies dated by SFH were within ±14 days of ultrasound confirmed dating. Using the 1 cm SFH = 1wk assumption, SFH underestimated GA compared with ultrasound-confirmed GA (mean bias: -14.0 days) with poor accuracy (95% limits of agreement [LOA]: ±42.8 days; n = 3 studies, 2447 pregnancies). Statistical modeling of three serial SFH measurements performed better, but accuracy was still poor (95% LOA ±33 days; n = 4 studies, 4391 pregnancies). In conclusion, there is wide variation in SFH measurement and SFH-to-GA conversion techniques. SFH is inaccurate for estimating GA and should not be used for GA dating. Increasing access to quality ultrasonography early in pregnancy should be prioritized to improve gestational age assessment in LMIC.

Epigenetic changes in peripheral leucocytes as biomarkers in intrauterine growth retardation rat

Epigenetics plays an important role in the fetal origins of adult disease. Intrauterine growth retardation (IUGR) can cause increased histone acetylation of the endothelin-1 (ET-1) gene from pulmonary vascular endothelial cells or the whole lung tissue and persist into later life, likely resulting in increased risk of pulmonary hypertension or asthma later in life. However, little is known regarding the correlation of epigenetic changes between specific tissue and peripheral leucocytes. In the present study, an IUGR rat model was established by maternal nutrient restriction. Peripheral blood leucocytes were isolated to detect the ET-1 expression level. Chromatin immunoprecipitation was used to analyze histone modification of the ET-1 gene promoter. The ET-1 protein expression of leucocytes from the 1-week IUGR group was similar to that from the 1-week control group. ET-1 protein expression of leucocytes from 10-week IUGR rats was obviously higher than that of the other groups (P<0.05). The levels of acetylated histone H3 in the ET-1 promoter of leucocytes from the 1-week IUGR rats were significantly higher than those from the age-matched control group (P=0.004). Furthermore, the trends continued ≤10 weeks after birth. In conclusion, epigenetic modifications of leucocytes can in part reflect the epigenetic changes of lung tissue in IUGR rats. Epigenetics of peripheral leucocytes may be used as a biomarker for predicting the risk of the development of disease, and may be used as a surrogate to investigate the subsequent development of pulmonary vascular disease or asthma.

Epigenetics of hypoxic pulmonary arterial hypertension following intrauterine growth retardation rat: epigenetics in PAH following IUGR

Background

Accumulating evidence reveals that intrauterine growth retardation (IUGR) can cause varying degrees of pulmonary arterial hypertension (PAH) later in life. Moreover, epigenetics plays an important role in the fetal origin of adult disease. The goal of this study was to investigate the role of epigenetics in the development of PAH following IUGR.

Methods

The IUGR rats were established by maternal undernutrition during pregnancy. Pulmonary vascular endothelial cells (PVEC) were isolated from the rat lungs by magnetic-activated cell sorting (MACS). We investigated epigenetic regulation of the endothelin-1 (ET-1) gene in PVEC of 1-day and 6-week IUGR rats, and response of IUGR rats to hypoxia.

Results

The maternal nutrient restriction increased the histone acetylation and hypoxia inducible factor-1α (HIF-1α) binding levels in the ET-1 gene promoter of PVEC in IUGR newborn rats, and continued up to 6 weeks after birth. These epigenetic changes could result in an IUGR rat being highly sensitive to hypoxia later in life, causing more significant PAH or pulmonary vascular remodeling.

Conclusions

These findings suggest that epigenetics is closely associated with the development of hypoxic PAH following IUGR, further providing a new insight for improved prevention and treatment of IUGR-related PAH.

Combined screening for preeclampsia and small for gestational age at 11-13 weeks

OBJECTIVE

To combine a specific algorithm for small for gestational age (SGA) without preeclampsia (PE) and another algorithm for PE in the prediction of SGA and PE.

METHODS

This was a screening study of singleton pregnancies at 11-13 weeks including 1,426 (2.3%) that subsequently developed PE, 3,168 (5.1%) that delivered SGA neonates and 57,458 that were unaffected by PE and SGA. We developed a prediction algorithm for SGA requiring delivery before 37 weeks' gestation (preterm-SGA) from maternal characteristics, uterine artery pulsatility index, mean arterial pressure, serum pregnancy-associated plasma protein-A and placental growth factor multiple of the median values. We then examined the performance of this algorithm individually and in combination with a previously reported algorithm for early-PE in the prediction of SGA and PE.

RESULTS

When screen positivity was defined by risk cutoff of 1:200 using the algorithm for early-PE and the risk cutoff of 1:150 using the algorithm for preterm-SGA, the false positive rate was 10.9% and the detection rates of early-PE, late-PE, preterm-SGA and term-SGA were 95.3, 45.6, 55.5 and 44.3%, respectively.

CONCLUSIONS

Effective first-trimester screening for early-PE and preterm-SGA can be provided by the combined use of the specific algorithms.

Risk factors and long-term health consequences of macrosomia: a prospective study in Jiangsu Province, China

We sought to determine risk factors associated with fetal macrosomia and to explore the long-term consequence of infant macrosomia at the age of 7 years. A prospective population based cohort study was designed to examine the associations between maternal and perinatal characteristics and the risk of macrosomia. A nested case-control study was conducted to explore the long-term health consequence of infant macrosomia. The mean maternal age of the macrosomia group was 24.74±3.32 years, which is slightly older than that in the control group (24.35±3.14 years, P = 0.000). The mean maternal body mass index (BMI) at early pregnancy was 22.75±2.81 kg/m², which was also higher than that in the control group (21.76±2.59 kg/m², P = 0.000). About 64.6% of macrosomic neonates were males, compared with 51.0% in the control group (P = 0.000). Compared with women with normal weight (BMI: 18.5-23.9 kg/m²), women who were overweight (BMI: 24-27.9 kg/m²) or obese (BMI≥28 kg/m²), respectively, had a 1.69-fold (P = 0.000) and a 1.49-fold (P = 0.000) increased risks of having a neonate with macrosomia, while light weight (BMI<18.5 kg/m²) women had an approximately 50% reduction of the risk. Furthermore, macrosomia infant had a 1.52-fold and 1.50-fold risk, respectively, of developing overweight or obesity at the age of 7 years (P = 0.001 and P = 0.000). Older maternal age, higher maternal BMI at early pregnancy and male gender were independent risk factors of macrosomia. Macrosomic infant was associated with an increased predisposition to develop overweight or obesity at the beginning of their childhood.

Modeling fetal weight for gestational age: a comparison of a flexible multi-level spline-based model with other approaches

We present a model for longitudinal measures of fetal weight as a function of gestational age. We use a linear mixed model, with a Box-Cox transformation of fetal weight values, and restricted cubic splines, in order to flexibly but parsimoniously model median fetal weight. We systematically compare our model to other proposed approaches. All proposed methods are shown to yield similar median estimates, as evidenced by overlapping pointwise confidence bands, except after 40 completed weeks, where our method seems to produce estimates more consistent with observed data. Sex-based stratification affects the estimates of the random effects variance-covariance structure, without significantly changing sex-specific fitted median values. We illustrate the benefits of including sex-gestational age interaction terms in the model over stratification. The comparison leads to the conclusion that the selection of a model for fetal weight for gestational age can be based on the specific goals and configuration of a given study without affecting the precision or value of median estimates for most gestational ages of interest.

First-trimester prediction of macrosomia

OBJECTIVE

To determine if combinations of maternal characteristics and measurements of parameters used in screening for aneuploidies at 11-13 weeks provide significant prediction of macrosomia.

METHOD

Maternal characteristics, fetal nuchal translucency (NT), free β-human chorionic gonadotrophin (β-hCG) and pregnancy-associated plasma protein-A (PAPP-A) were recorded at 11(+0)-13(+6) weeks in 36,743 singleton pregnancies. Regression analysis was used to determine if in predicting macrosomia significant contributions are provided by maternal factors, fetal NT, free β-hCG and PAPP-A.

RESULTS

The risk for macrosomia increased with maternal weight and height and was higher in parous women with previous delivery of a macrosomic baby and in those with diabetes mellitus; the risk was lower in women of African and South Asian racial origins, in cigarette smokers and in those with chronic hypertension. In the macrosomic group compared to the unaffected group there were higher Δ-NT (0.167 vs. 0.116 mm), free β-hCG (1.010 vs. 0.964 MoM) and PAPP-A (1.103 vs. 1.003 MoM). Prediction of macrosomia provided by maternal factors was significantly improved by fetal NT, free β-hCG and PAPP-A (34.4 vs. 33.1% at a false-positive rate of 10%).

CONCLUSION

Prediction of macrosomia is provided in the first trimester of pregnancy by a combination of maternal characteristics and measurements of parameters used in screening for aneuploidies.

Fetal growth compromise: definitions, standards, and classification

Fetal growth compromise is mostly defined by gestational age specific threshold value of birth weight or ultrasonically estimated fetal weight. The most frequently used threshold is the 10th centile. However, this approach can not differentiate fetal constitutional smallness from fetal growth failure. The most common descriptor terms are fetal growth restriction (FGR), intrauterine growth restriction and small for gestational age. It is recommended to restrict the use of the first two terms to prenatal assessment of growth and the last term to assessment of the birth weight. Growth reference charts are affected by physiological and methodological variables. There is controversy on whether the reference charts should be customized by multiple variables or inclusive of the whole population. Symmetric FGR is more common and has better outcome than asymmetric FGR. However, such a classification may not be clinically relevant.

Induction of labor in twin pregnancy after 36 weeks does not increase maternal-fetal morbidity

OBJECTIVE

To compare maternal and perinatal outcomes in twin pregnancy patients without any fetal or maternal disease, managed by labor induction or expectant management after 36 weeks gestation.

METHODS

We conducted a case-control study of 81 patients: labor induction (n=36) vs. expectant management (n=45). Labor was induced using oxytocin (n=18), vaginal prostaglandins (n=6) or intrauterine balloon catheter (n=12) according to the Bishop score. Maternal and perinatal outcome variables were compared among both groups.

RESULTS

The characteristics of the labor induction group and the expectant management group were not statistically different, except for the rate of nulliparae (55.6% vs. 33.3%) and the rate of epidural analgesia (100% vs. 80%). There was no significant difference in labor time (6.5+/-2.8 h vs. 6.0+/-3.6 h), cesarean section rate (8.3% vs. 13.3%) or duration of maternal hospitalization (7.3+/-2.0 days vs. 7.5+/-2.3 days) in the labor induction group and in the expectant management group, respectively. The birth weight was higher in the labor induction group than in the expectant management group (2639+/-352 g vs. 2463+/-298 g, P<0.001). The rate of Apgar score <7 at 5 min was 0% and 3.3%, respectively. Neonatal intensive care unit admission occurred in 30.5% and 26.6% of the groups, respectively. No perinatal death was reported.

CONCLUSION

Induction of labor may be proposed to patients with uneventful twin pregnancy after 36 weeks gestation without increasing maternal-fetal morbidity.

Menstrual age-dependent systematic error in sonographic fetal weight estimation: a mathematical model

PURPOSE

We used computer modeling techniques to evaluate the accuracy of different types of sonographic formulas for estimating fetal weight across the full range of clinically important menstrual ages.

METHODS

Input data for the computer modeling techniques were derived from published British standards for normal distributions of sonographic biometric growth parameters and their correlation coefficients; these standards had been derived from fetal populations whose ages were determined using sonography. The accuracy of each of 10 formulas for estimating fetal weight was calculated by comparing the weight estimates obtained with these formulas in simulated populations with the weight estimates expected from birth weight data, from 24 weeks' menstrual age to term. Preterm weights were estimated by interpolation from term birth weights using sonographic growth curves. With an ideal formula, the median weight estimates at term should not differ from the population birth weight median.

RESULTS

The simulated output sonographic values closely matched those of the original population. The accuracy of the fetal weight estimation differed by menstrual age and between various formulas. Most methods tended to overestimate fetal weight at term. Shepard's formula progressively overestimated weights from about 2% at 32 weeks to more than 15% at term. The accuracy of Combs's and Shinozuka's volumetric formulas varied least by menstrual age. Hadlock's formula underestimated preterm fetal weight by up to 7% and overestimated fetal weight at term by up to 5%.

CONCLUSIONS

The accuracy of sonographic fetal weight estimation based on volumetric formulas is more consistent across menstrual ages than are other methods.

Fetal growth

Recent epidemiological and experimental studies show that abnormal fetal growth can lead to serious complications, including stillbirth, perinatal morbidity and disorders extending well beyond the neonatal period. It is now clear that the intrauterine milieu is as important as genetic endowment in shaping the future health of the conceptus. Maternal characteristics such as weight, height, parity and ethnic group need to be adjusted for, and pathological factors such as smoking excluded, to establish appropriate standards and improve the distinction between what is normal and abnormal. Currently, the aetiology of growth restriction is not well understood and preventative measures are ineffective. Elective delivery remains the principal management option, which emphasizes the need for better screening techniques for the timely detection of intrauterine growth failure.

Monitoring technology and the clinical perspective

Currently available technology requires a new look to reduce intervention as well as to improve the detection of the truly at-risk fetus. Iatrogenic causes of so-called fetal distress, in particular the administration of uterotonics without due attention to avoiding hyperstimulation, predominate as a reason for intervention. There needs to be a better definition of the starting point, i.e assessment of the fetal condition and identification of any risk factors, such as oligohydramnios and growth retardation, that might diminish fetal reserve. This will allow 'customization' of surveillance and management according to the needs of each individual fetus. There also needs to be better training and better agreement about the end-point of monitoring. For prospective surveillance, the aim is to avoid rather than to identify damage, and the definition of the appropriate point for intervention needs to come from better consensus on what is and what is not acceptable management based on current knowledge. New technology holds the promise that it can give trended information during labour, allow early recognition of problems and reduce unnecessary intervention. However, there is a need to ensure reliability and reproducibility of the readings before a new method is released. Co-operation with industry is essential, but the roles need to be well defined and the ultimate responsibility for establishing the role of a new technique has to come from the clinicians involved in intrapartum care.