Tracking and Determinants of Kidney Size From Fetal Life Until the Age of 2 Years: The Generation R Study
Received 4 March 2007; accepted 15 July 2008. published online 13 October 2008.
Background
An adverse fetal environment may lead to smaller kidneys and subsequently kidney disease and hypertension in adulthood. The aims of this study are to examine whether kidney size tracks from fetal life to childhood and whether maternal and fetal characteristics are associated with kidney size at the age of 2 years.
Study Design
Prospective cohort study from fetal life onward.
Setting & Participants
The study was conducted in a group of 688 infants in Rotterdam, The Netherlands. Entry criteria were singleton, noncomplicated pregnancies, and Dutch ethnicity.
Predictors
The maternal characteristics age, height, and prepregnancy weight were measured in early pregnancy. Fetal growth, head circumference, abdominal circumference, femur length and estimated fetal weight, and placental characteristics were assessed in the second and third trimesters.
Outcomes & Measurements
Kidney size, defined as length, width, depth, and volume, was measured in the third trimester of pregnancy and at postnatal ages 6 and 24 months.
Results
Overall median gestational age was 40.3 weeks (95% range, 36.0 to 42.3 weeks), and mean birth weight was 3,536 ± 524 (SD) g. Children tended to remain in the lowest and highest quartiles of kidney volume from the third trimester to the age of 2 years (odds ratio, 2.05; 95% confidence interval, 1.38 to 3.06; odds ratio, 3.29; 95% confidence interval, 2.22 to 4.87, respectively). Maternal height and prepregnancy weight were associated positively with kidney volume at the age of 2 years. Third-trimester fetal head circumference, abdominal circumference, and estimated weight and postnatal length were associated positively with kidney volume at the age of 2 years. Preferential fetal blood flow to the brain was associated with smaller kidneys.
Limitations
Kidney measurements successfully performed in only 86% of children.
Conclusions
Small kidney size in fetal life tends to persist in early childhood. Maternal anthropometrics and fetal biometrics and blood flow patterns are associated with kidney size in childhood. Follow-up studies are needed to examine whether these variations in kidney size are related to kidney function and blood pressure in later life.
1The Generation R Study Group, Erasmus Medical Center, Rotterdam, The Netherlands
2Department of Epidemiology, Erasmus Medical Center, Rotterdam, The Netherlands
3Department of Pediatrics, Erasmus Medical Center, Rotterdam, The Netherlands
4Department of Obstetrics and Gynaecology, Erasmus Medical Center, Rotterdam, The Netherlands
5Department of Radiology, Erasmus Medical Center, Rotterdam, The Netherlands
Address correspondence to Vincent W.V. Jaddoe, MD, PhD, The Generation R Study Group (AE-006), Erasmus MC, PO Box 2040, 3000 CA Rotterdam, The Netherlands
ABSTRACT