Fetal Kidney Volume Research Articles

Administration of retinoic acid to pregnant mice increases the number of fetal mouse glomeruli

The prevalence of chronic kidney disease (CKD) is increasing worldwide, and CKD is a serious global health problem. Low glomerular number is one of the risk factors for CKD; therefore, the glomerular number is associated with the risk of CKD. Increasing the glomerular number above normal levels may reduce the risk of CKD. It has been reported that, in vitro, the addition of retinoic acid (RA) to the culture medium increases the glomerular number. However, there is no report of an increase in glomerular number above normal levels with the addition of RA in vivo. In this study, RA (20 mg/kg) was administered intraperitoneally to pregnant mice once at embryonic day (E) 10.5, E12.5, E14.5, or E16.5. The fetuses were harvested at E18.5 and fetal mouse kidneys were evaluated. Fetal kidney volume and weight were significantly increased in the E16.5 group compared to the control group. The total glomerular number in the E16.5 group was also approximately 1.46 times higher than that in the control group. In summary, we established a method to increase the glomerular number in the fetal kidney by administration of RA to pregnant mice at E16.5. These results will facilitate the investigation of whether CKD risk is reduced when the glomerular number increases above normal.

Innovative approach for first-trimester fetal organ volume measurements using a Virtual Reality system: The Generation R Next Study.

IntroductionTo investigate the reproducibility of first‐trimester fetal organ volume measurements using three‐dimensional (3D) ultrasound and a Virtual Reality system.MethodsWithin a population‐based prospective cohort study, 3D ultrasound datasets of 25 first‐trimester fetuses were collected by three sonographers. We used the V‐scope application to perform Virtual Reality volume assessments of the fetal heart, lungs, and kidneys. All measurements were performed by two independent researchers.ResultsIntraobserver analyses for volume measurements of the fetal heart, lungs, and kidneys showed intraclass correlation coefficients ≥0.86, mean differences ≤8.3%, and coefficients of variation ≤22.8%. Interobserver analyses showed sufficient agreement for right lung volume measurements, but consistent measurement differences between observers for left lung, heart, and kidney volume measurements (p‐values <0.05).ConclusionWe observed sufficient intraobserver reproducibility, but overall suboptimal interobserver reproducibility for first‐trimester fetal heart, lung, and kidney volume measurements using an innovative Virtual Reality approach. In the current stage, these measurements might be promising for the use in research settings. The reproducibility of the measurements might be further improved by novel post‐processing algorithms.

Maternal Diet Influences Fetal Growth but Not Fetal Kidney Volume in an Australian Indigenous Pregnancy Cohort.

Suboptimal nutrition during pregnancy is recognised as a significant modifiable determinant in the development of chronic disease in offspring in later life. The current study aimed: (i) to assess the dietary intakes of pregnant Indigenous Australian women against national recommendations and (ii) to investigate the associations between maternal nutrition during pregnancy and the growth of the offspring, including kidney development in late gestation in the Gomeroi gaaynggal cohort (n = 103). Maternal dietary intake in the third trimester was assessed using the Australian Eating Survey Food Frequency Questionnaire. Estimated fetal weight (EFW) and kidney size were obtained by ultrasound. Birth weight was retrieved from hospital birth records. Of the five key nutrients for optimal reproductive health (folate, iron, calcium, zinc and fibre), the nutrients with the highest percentage of pregnant women achieving the nutrient reference values (NRVs) were zinc (75.7%) and folate (57.3%), whereas iron was the lowest. Only four people achieved all NRVs (folate, iron, calcium, zinc and fibre) important in pregnancy. Sodium and saturated fat intake exceeded recommended levels and diet quality was low, with a median score of 28 out of 73 points. After adjusting for smoking and pre-pregnancy body mass index, only maternal intake of retinol equivalents and the proportion of energy from nutrient-dense or energy-dense, nutrient-poor (EDNP) foods were associated with fetal growth. EFW decreased by 0.13 g and birth weight decreased by 0.24 g for every µg increase in maternal dietary retinol intake. Interestingly, EFW, but not actual birth weight, was positively associated with percentage energy from nutrient dense foods and negatively associated with percentage energy from EDNP foods. Dietary supplement usage was associated with increased birthweight, most significantly iron and folate supplementation. Current dietary intakes of pregnant Australian women from this cohort do not align with national guidelines. Furthermore, current findings show that maternal retinol intake and diet composition during pregnancy can influence fetal growth, but not fetal kidney growth in late gestation. Strategies that aim to support and optimise nutrient intakes of Indigenous pregnant women are urgently needed. Future studies with long-term follow-up of the children in the current cohort to assess renal damage and blood pressure are imperative.

SAT-307 NORMAL FETAL KIDNEY VOLUME AND INFANT URINALYSIS IN OFFSPRING OF WOMEN TREATED FOR GESTATIONAL DIABETES

The worldwide prevalence of gestational diabetes mellitus (GDM), defined as any degree of glucose intolerance with onset or first recognition during pregnancy, is increasing, and affects up to 20% of pregnancies. Evidence from animal studies indicate that maternal hyperglycemia can be detrimental to renal development and kidney function in exposed offspring. In humans, renal dysfunction and disease has been reported in adults whose mothers had Type 1 or Type 2 diabetes, suggesting that pre-gestational maternal diabetes influences kidney development and the risk of renal dysfunction in adulthood. Despite its high prevalence, few studies have examined kidney development or renal function in offspring of women with GDM. The aim of this study was to evaluate the impact of treated GDM on fetal kidney size and infant renal physiology. A prospective cohort study was conducted between June 2013 and August 2016 in Melbourne, Australia. Participants were recruited at a large public university teaching hospital and clinical data were collected from women without GDM (n=82) and women diagnosed and treated for GDM (n=76). GDM was diagnosed by routine screening at 26-28 weeks gestation. Women with GDM received specialist support for glucose monitoring, diet and exercise in addition to routine antenatal care. One-third of women with GDM also required insulin therapy. Participants underwent an obstetric ultrasound at 32-34 weeks gestation for fetal biometry and fetal kidney volume measurement. Quantitative urinalyses were performed in infant urine samples at 3 months of age for analysis of protein and electrolytes. Maternal age, weight and body mass index were similar in no-GDM and GDM women. Estimated fetal weight and birth weight were also similar in no-GDM and GDM pregnancies. There were no differences in fetal kidney dimensions, total kidney volume, infant urinary albumin or electrolyte levels. Fetal kidney size did not differ by mode of GDM treatment (i.e. diet and exercise alone, or diet and exercise with insulin therapy). There were no associations between maternal glucose levels at screening and fetal total kidney volume or infant urine albumin in multivariable regression analyses. Findings suggest that a limited period of hyperglycemia prior to diagnosis and treatment of GDM in women attending a large metropolitan public hospital in Australia does not alter fetal kidney volume at 32-34 weeks gestation or urinalysis in 3-month-old infants, a favourable finding considering the increasing number of women diagnosed with GDM.

Ultrasonic determination of gestational age by assessment of fetal kidney size in the third trimester in southwest Nigeria.

To determine the strength of association between fetal kidney measurements and gestational age (GA) in third-trimester pregnancies. In a cross-sectional study in Ile-Ife, Nigeria, women in the third trimester of a singleton pregnancy who were sure of the date of their last menstrual period or had an early pregnancy scan were recruited consecutively in 2012. Standard biometric measurements were taken, along with fetal kidney length (FKL), anteroposterior diameter (FKAPD), and transverse diameter (FKTD). Fetal kidney volume (FKV) was calculated via the ellipsoid formula. Data were analyzed by Pearson correlation and multivariate linear regression. In total, 470 women were recruited. Compared with standard biometric parameters, renal parameters showed better correlation with GA. Among the standard parameters, femur length showed the strongest correlation with GA. FKL and FKV showed stronger positive correlation with GA as compared with FKTD and FKAPD. In multivariate linear regression modeling, FKL alone predicted GA with accuracy of ±10.1days, whereas a combination of standard and kidney parameters predicted GA with better accuracy of ±8.0days. Compared with standard biometric parameters, fetal renal parameters correlated better with GA in the third trimester. Among the renal parameters, FKL correlated most strongly with GA.

Reference ranges for ultrasound measurements of fetal kidneys in a cohort of low-risk pregnant women.

Alterations in renal dimensions may be an early manifestation of deviation from normality, with possible repercussions beyond intrauterine life. The objective of this study was to establish reference curves for fetal kidney dimensions and volume from 14 to 40weeks of gestation. This is a prospective longitudinal study of 115 Brazilian participants in the "WHO multicentre study for the development of growth standards from fetal life to childhood: the fetal component". Pregnant women with clinical and sociodemographic characteristics allowing the full potential fetal growth were followed up from the first trimester until delivery. These women underwent serial sonographic evaluation of fetal kidneys. The longitudinal, anteroposterior and transverse diameters of both fetal kidneys were measured, in addition to calculation of kidney volume. By quantile regression analysis, reference curves of renal measurements related to gestational age were built. Standard normal sonographic values of renal biometry were defined during pregnancy. Reference values for the 10th, 50th and 90th centiles of different fetal kidney measurements (longitudinal, anteroposterior, transverse and volume) from the 14th to the 40th week of gestation were fitted. The reference curves presented should be of the utmost importance for screening and diagnosis of alterations in renal development during the intrauterine period.

The relationship between maternal obesity and diabetes during pregnancy on offspring kidney structure and function in humans: a systematic review.

Evidence from animal models indicates that exposure to an obesogenic or hyperglycemic intrauterine environment adversely impacts offspring kidney development and renal function. However, evidence from human studies has not been evaluated systematically. Therefore, the aim of this systematic review was to synthesize current research in humans that has examined the relationship between gestational obesity and/or diabetes and offspring kidney structure and function. Systematic electronic database searches were conducted of five relevant databases (CINAHL, Cochrane, EMBASE, MEDLINE and Scopus). Preferred Reporting Items for Systematic Reviews and Meta-analysis guidelines were followed, and articles screened by two independent reviewers generated nine eligible papers for inclusion. Six studies were assessed as being of 'neutral' quality, two of 'negative' and one 'positive' quality. Observational studies suggest that offspring exposed to a hyperglycemic intrauterine environment are more likely to display markers of renal dysfunction and are at higher risk of end-stage renal disease. There was limited and inconsistent evidence for a link between exposure to an obesogenic intrauterine environment and offspring renal outcomes. Offspring renal outcome measures across studies were diverse, with a large variation in offspring age at follow-up, limiting comparability across studies. The collective current body of evidence suggests that intrauterine exposure to maternal obesity and/or diabetes adversely impacts renal programming in offspring, with an increased risk of kidney disease in adulthood. Further high-quality, longitudinal, prospective cohort studies that measure indicators of offspring renal development and function, including fetal kidney volume and albuminuria, at standardized follow-up time points, are warranted.

Fetal Renal Volume and Renal Artery Doppler in Normal and Intrauterine Growth Restricted Fetuses

Objective: To evaluate the difference between fetal renal artery Doppler and fetal kidney volume in normal and intrauterine growth restricted fetuses Design: A prospective cross sectional study. Setting: Obstetrics and Gynecology department, Al-Azhar University. Sample: One hundred pregnant women, 50 with normal fetal growth parameter, and 50 with restricted fetal growth. Methods: Fetal renal volume was measured using 3-dimensional ultrasound. Umbilical artery and fetal renal artery Doppler indices were examined. Main outcome measures: Correlation of Doppler parameter to fetal kidney volume, and association of fetal biometric indices to combined fetal kidney volume. Results: Combined fetal renal volume was significantly reduced in growth restricted fetuses than in normally grown fetuses as the Mean of combined renal volume in IUGR was (21.0 ± 0.1) while in normal fetuses was (31.24±2.31). All fetal biometric indices were positively associated with combined kidney volume. Concerning the umbilical artery Doppler and fetal renal artery Doppler there was significantly difference between the two groups as the intrauterine growth restricted fetuses have a high Doppler. Conclusion: Intrauterine growth restriction appears to be associated with a statistically significant decrease in the renal volume than the normally growth fetuses. The renal artery Doppler shows also significant difference between the two groups, which matches with other studies. This study supports the hypothesis that intrauterine growth restriction may be linked to renal disease and hypertension in late life and renal volume can be used as a parameter for diagnosis of IUGR.

Fetal Renal Volume and Renal Artery Doppler in Normal and Intrauterine Growth Restricted Fetuses

Objective: To evaluate the difference between fetal renal artery Doppler and fetal kidney volume in normal and intrauterine growth restricted fetuses Design: A prospective cross sectional study. Setting: Obstetrics and Gynecology department, Al-Azhar University. Sample: One hundred pregnant women, 50 with normal fetal growth parameter, and 50 with restricted fetal growth. Methods: Fetal renal volume was measured using 3-dimensional ultrasound. Umbilical artery and fetal renal artery Doppler indices were examined. Main outcome measures: Correlation of Doppler parameter to fetal kidney volume, and association of fetal biometric indices to combined fetal kidney volume. Results: Combined fetal renal volume was significantly reduced in growth restricted fetuses than in normally grown fetuses as the Mean of combined renal volume in IUGR was (21.0 ± 0.1) while in normal fetuses was (31.24±2.31). All fetal biometric indices were positively associated with combined kidney volume. Concerning the umbilical artery Doppler and fetal renal artery Doppler there was significantly difference between the two groups as the intrauterine growth restricted fetuses have a high Doppler. Conclusion: Intrauterine growth restriction appears to be associated with a statistically significant decrease in the renal volume than the normally growth fetuses. The renal artery Doppler shows also significant difference between the two groups, which matches with other studies. This study supports the hypothesis that intrauterine growth restriction may be linked to renal disease and hypertension in late life and renal volume can be used as a parameter for diagnosis of IUGR.

A possible new approach in the prediction of late gestational hypertension: The role of the fetal aortic intima-media thickness.

The aim was to determine the predictive role of combined screening for late-onset gestational hypertension by fetal ultrasound measurements, third trimester uterine arteries (UtAs) Doppler imaging, and maternal history. This prospective study on singleton pregnancies was conducted at the tertiary center of Maternal and Fetal Medicine of the University of Padua during the period between January 2012 and December 2014. Ultrasound examination (fetal biometry, fetal wellbeing, maternal Doppler study, fetal abdominal aorta intima-media thickness [aIMT], and fetal kidney volumes), clinical data (mother age, prepregnancy body mass index [BMI], and parity), and pregnancy outcomes were collected. The P value <0.05 was defined significant considering a 2-sided alternative hypothesis. The distribution normality of variables were assessed using Kolmogorov-Smirnoff test. Data were presented by mean (±standard deviation), median and interquartile range, or percentage and absolute values. We considered data from 1381 ultrasound examinations at 29 to 32 weeks' gestation, and in 73 cases late gestational hypertension developed after 34 weeks' gestation. The final multivariate model found that fetal aIMT as well as fetal umbilical artery pulsatility index (PI), maternal age, maternal prepregnacy BMI, parity, and mean PI of maternal UtAs, assessed at ultrasound examination of 29 to 32 weeks' gestation, were significant and independent predictors for the development of gestational hypertension after 34 weeks' gestation. The area under the curve of the model was 81.07% (95% confidence interval, 75.83%-86.32%). A nomogram was developed starting from multivariate logistic regression coefficients. Late-gestational hypertension could be independently predicted by fetal aIMT assessment at 29 to 32 weeks' gestation, ultrasound Doppler waveforms, and maternal clinical parameters.

Comparison of conventional versus three-dimensional ultrasound in fetal renal pelvis measurement and their potential prediction of neonatal uropathies

Objective: To establish a threshold value for fetal renal pelvis dilatation measured by automatic volume calculation (SonoAVC) in the third trimester of pregnancy to predict neonatal uropathies, and to compare these results with conventional antero–posterior (AP) measurement, fetal kidney 3D volume and renal parenchymal thickness. Methods: In a prospective cohort study, 125 fetuses with renal pelvis AP diameter of ≥5 mm both at 20 weeks of gestation and in the third trimester, underwent an additional 3D volume measurement of the fetal kidney in the third trimester. Receiver operating characteristic (ROC) curves for establishing threshold values for fetal renal pelvis volume, AP measurement, fetal kidney volume and renal parenchymal thickness to predict neonatal uropathies were analyzed. Also, sensitivity, specificity, area under the curve (AUC) and likelihood ratios were calculated. Results: A cut-off point of 1.58 cm³ was identified in the third trimester of pregnancy (AUC 0.865 (95% CI 0.789–0.940), sensitivity 76.3%, specificity 87.4%, LR+ 6.06, LR− 0.27) for measurements with SonoAVC. A cut-off value of 11.5 mm was established in the third trimester of pregnancy (AUC 0.828 (95% CI 0.737–0.918), sensitivity 71.1%, specificity 85.1%, LR+ 4.77, LR− 0.34) for the conventional AP measurement. A cut-off point for fetal kidney volume was calculated at 13.29 cm³ (AUC 0.769 (95% CI 0.657–0.881), sensitivity 71%, specificity 66%, LR+ 2.09, LR− 0.44). For renal parenchymal thickness, a cut-off point of 8.4 mm was established (AUC 0.216 (95% CI 0.117–0.315), sensitivity 31.6%, specificity 32.6%, LR+ 0.47, LR− 2.10). Conclusion: This study demonstrates that 3D fetal renal pelvis volume measurements and AP measurements both have a good and comparable diagnostic performance, fetal renal volume a fair accuracy and renal parenchymal thickness a poor accuracy in predicting postnatal renal outcome.

Fetal Endothelial Remodeling in Late-Onset Gestational Hypertension.

Recent studies reveal that offspring of pregnancies complicated by hypertensive disorders may have an increased cardiovascular risk. Genetic and nongenetic factors seem to play an important role in premature arterial disease. Endothelium may be significant for long-term remodeling of the arterial wall. The aim of the study was to assess fetal endothelial and renal function in late-onset gestational hypertension. This was a case-controlled study. Singleton pregnancies affected by late-onset gestational hypertension (after 34 weeks' gestation) and controls were included. Ultrasound examinations (fetal biometry, fetal Doppler, fetal aorta intima media thickness (aIMT), fetal kidney volumes, maternal Doppler, presence of uterine arteries protodiastolic notching from anomaly scan) and clinical data were collected. A sample of amniotic fluid was taken at delivery. Fifty patients with late-onset hypertension and 50 controls were included. At growth scan (weeks 29-32) we found in the study group significantly higher fetal aIMT, umbilical artery pulsatility index (PI), fetal aorta PI, and mean uterine arteries PI with persistent bilateral notch. In the case group microalbuminuria levels were significantly higher than controls (1.32±0.11 vs. 1.10±0.13g/l, P < 0.0001), and there was a negative correlation between renal fetal volume at growth scan and amniotic microalbuminuria (r: -0.95, 95% C -0.97 to -0.90, P < 0.0001). Gestational hypertension should be considered as one of the adverse early risk factors that might predispose to impaired fetal cardiovascular development during intrauterine life; therefore, this study provides further evidence to better understand the origins of cardiovascular diseases.

Childhood kidney outcomes in relation to fetal blood flow and kidney size.

Impaired fetal abdominal blood flow may lead to smaller kidneys and subsequent impaired kidney function in later life. In a prospective cohort study among 923 pregnant women and their children, we measured fetal growth, kidney volumes, and umbilical and cerebral artery blood flow (median gestational age of 30.3 weeks; 95% range, 28.5-32.7 weeks). We used a higher umbilical/cerebral artery pulsatility index ratio as an indicator of preferential fetal blood flow to the upper body parts at the expense of the intra-abdominal organs. At a median age of 5.9 years (95% range, 5.7-6.6 years), we measured childhood kidney volumes, creatinine and cystatin C blood levels, microalbuminuria, BP, and eGFR. A preferential fetal blood flow to the upper body parts at the expense of the intra-abdominal organs associated only with a smaller combined kidney volume in childhood. Fetal combined kidney volume positively associated with childhood combined kidney volume and eGFR, and inversely associated with childhood creatinine and cystatin C levels (all P values <0.05), but did not associate with childhood microalbuminuria and BP. Children within the highest tertile of fetal umbilical/cerebral ratio and the lowest tertile of fetal combined kidney volume had the lowest eGFR (difference, -6.36 ml/min per 1.73 m(2); 95% confidence interval, -11.78 to -0.94 compared with children within the middle tertiles). These data suggest that impaired fetal blood to the abdominal organs and smaller fetal kidney size are associated with subclinical changes in kidney outcomes in school-aged children.

Does hyperglycemia in pregnancy change fetal kidney growth?: a longitudinal prospective study

To measure fetal renal volume in normoglycemic and hyperglycemic pregnancies. A longitudinal prospective study was conducted and included 92 hyperglycemic and 339 normoglycemic pregnant women attended at the prenatal service of a hospital from Rio de Janeiro State. Ultrasound examinations were performed to estimate gestational age at baseline and the kidney volume was estimated using the prolate ellipsoid volume equation. Fetal kidney volume growth between normoglycemic and hyperglycemic pregnancies are significantly different. The fetal kidney volume growth in pregnancy is positively correlated with gestational age explained by these predictor equations, by group: normal renal volume = exp (6.186 + 0.09 × gestational week); hyperglycemic renal volume = exp (6.978 + 0.071 × gestational week) and an excessive growth pattern for hyperglycemic pregnancies may be established according to gestational age. This is important for early detection of abnormalities in pregnancy, particularly in diabetic mothers.

Renal Volumes Measured by 3-Dimensional Sonography in Healthy Fetuses From 20 to 40 Weeks

The purpose of this study was to establish reference values for fetal kidney volumes as a function of gestational age, estimated by 3-dimensional sonography using the Virtual Organ Computer-Aided Analysis (VOCAL) technique (GE Healthcare, Kretztechnik, Zipf, Austria). Volumes of right and left kidneys were assessed in 213 healthy fetuses by 3-dimensional sonography using the VOCAL technique. Inclusion criteria were healthy women with singleton pregnancies, unremarkable comprehensive fetal sonographic findings, well-known gestational age established by first-trimester sonography, and gestational ages between 20 and 40 weeks. Exclusion criteria were patients lost to follow-up and birth weight abnormalities. Each patient was scanned once during pregnancy. Regression analysis was used to calculate unified formulas. The mathematical models calculated in the study were as follows: expected right kidney volume = exp[-1.01 + (0.12 × gestational age)]; and expected left kidney volume = exp[-0.90 + (0.12 × gestational age)]. No significant intraobserver or inter-observer variability was observed for the determined volumes. Reference values for right and left fetal kidney volumes throughout gestation using the rotational technique (VOCAL) are described. The use of this technique might aid in further definition of gestational age kidney volume standards to help in defining variations from the norm.

Size and volume charts of fetal kidney, renal pelvis and adrenal gland

To establish reference curves for size and volume of the fetal kidney, renal pelvis and adrenal gland, as measured using ultrasound from the 15(th) week of gestation. This was a prospective, longitudinal study of 96 fetuses in low-risk singleton pregnancies, in which we performed serial ultrasound examinations at 4-week intervals. The length and anteroposterior and transverse diameters of both kidneys, the anteroposterior and transverse diameters of the renal pelvises and the length of the adrenal glands were measured three times at each examination, with the average being used for further analysis. Reference charts were constructed using multilevel statistical analysis and comparisons were made with previously published charts derived from cross-sectional data. We present nomograms for fetal kidney dimensions and volume, renal pelvis dimensions and adrenal gland length. The new charts show differences in shape and have narrower percentile bands in comparison to previously published reference ranges. These new charts of measurements of the fetal kidney, renal pelvis and adrenal gland, from a prospective, longitudinal study, may be useful in the diagnosis and assessment of pathology of the kidney and adrenal gland.

P27.10: Nomograms of fetal kidney volumes measured by three‐dimensional ultrasonography

P27.10: Nomograms of fetal kidney volumes measured by three‐dimensional ultrasonography

Genetic variants associated with adult blood pressure and kidney function do not affect fetal kidney volume. The Generation R Study

BackgroundSmaller kidneys with reduced number of nephrons in early life lead to impaired kidney function and risk for hypertension and chronic kidney disease. These associations might be partly explained by common genetic variation. AimsTo assess the associations between common genetic variants, which have recently shown to be associated with blood pressure or kidney function, with fetal kidney volume. Study designA prospective population based cohort study in Rotterdam, The Netherlands. Subjects855 children, followed from early fetal life onwards (born 2003–2005). PredictorCommon genetic variants previously associated with blood pressure or kidney function. Outcome measuresCombined third trimester fetal kidney volume. ResultsAfter taking into account multiple testing, only rs12940887 (near ZNF652) was significantly associated with fetal kidney volume (β: 0.88 (95% CI: 0.40; 1.37) cm3 per minor allele, P-value<0.001), but the effect showed the opposite direction as expected. The remaining common genetic variants were not associated with fetal kidney volume. We also did not find associations of genetic variants previously shown to affect newborn kidney volume, with third trimester fetal kidney volume. ConclusionsOur results suggest that common genetic variants, associated with kidney function or disease and blood pressure, do not affect the third trimester fetal kidney volume. Further studies are needed to elucidate the mechanisms underlying the associations between small kidney size and increased risks of hypertension and impaired kidney function in adulthood.

Fetal Renal Volume and Fetal Doppler in Normal and Growth Restricted Fetuses: Is there a Correlation?

Objective: To evaluate if umbilical, middle cerebral and fetal renal artery Doppler could affect fetal kidney volume in healthy and growth restricted fetuses after 26 weeks of gestation. Design: A prospective cross sectional study. Setting: Obstetrics& Gynecology department, Zagazig University, Egypt. Sample: One hundred ten pregnant women, 77 with normal fetal growth parameter, and 43 with IUGR fetuses. Methods: Fetal renal volume, combined and relative kidney volume were measured using 2-dimensional ultrasound. Umbilical, middle cerebral artery and fetal renal artery Doppler indices were examined. Main outcome measures: Correlation of Doppler parameter to fetal kidney volume, and association of fetal biometric indices to combined fetal kidney volume. Results: Combined and relative fetal kidney volume was significantly reduced in growth restricted fetuses than in normally grown fetuses 29% (95% CI, 18%-37%), for the former and 18% (95% CI, 3%-22) for the latter. All fetal biometric indices were positively associated with combined kidney volume. The largest effects were found for estimated fetal weight and abdominal circumference after adjustment for gestational age. No correlation exists between umbilical or middle cerebral artery Doppler and fetal renal volume. A significant negative correlation was found between fetal renal artery pulsatility index and fetal renal volume after adjustment for abdominal circumference. Conclusion: Increased fetal renal artery pulsatility index in growth restricted fetuses is negatively correlated with fetal kidney volume with resultant decreased renal perfusion and impaired nephrogensis.

Maternal smoking during pregnancy and kidney volume in the offspring: the Generation R Study

An adverse fetal environment leads to smaller kidneys, with fewer nephrons, which might predispose an individual to the development of kidney disease and hypertension in adult life. In a prospective cohort study among 1,072 children followed from early fetal life onward, we examined whether maternal smoking during pregnancy, as a significant adverse fetal exposure, is associated with fetal (third trimester of pregnancy, n = 1,031) and infant kidney volume (2 years of age, n = 538) measured by ultrasound. Analyses were adjusted for various potential confounders. Among mothers who continued smoking, we observed dose-dependent associations between the number of cigarettes smoked during pregnancy and kidney volume in fetal life. Smoking less than five cigarettes per day was associated with larger fetal combined kidney volume, while smoking more than ten cigarettes per day tended to be associated with smaller fetal combined kidney volume (p for trend: 0.002). This pattern was not significant for kidney volume at the age of 2 years. Our results suggest that smoking during pregnancy might affect kidney development in fetal life with a dose-dependent relationship. Further studies are needed to assess the underlying mechanisms and whether these differences in fetal kidney volume have postnatal consequences for kidney function and blood pressure.