Kidney growth in twin children born small for gestational age.
BACKGROUND
Low birth weight (LBW) is associated with adult-onset diseases, including hypertension and renal disease; altered renal development after intrauterine growth restriction (IUGR) may underlie related prenatal programming. No data are available on longitudinal renal growth in twin infants born small for gestational age (SGA). The aim of this prospective longitudinal study was to estimate the renal size during the first 2 years of life in SGA twin infants.


METHODS
The study included 613 children, of which 145 were SGA twins, 141 twins appropriate for gestational age (AGA), 148 matched AGA singletons and 179 matched SGA singletons, classified according to GA into two groups (28-36 and >36 weeks). The SGA children were also classified according to the degree of IUGR: birth weight (BW) <3rd percentile and BW 3rd-10th percentiles. Serial renal ultrasonography (US) for kidney length (KL) measurement was performed at the ages of 36 and 40 weeks corrected age (CA) and 3, 6, 12 and 24 months of age, and KL was related to other anthropometric indices. Twin data were examined both as individuals and as members of twin pairs.


RESULTS
A total of 2317 measurements were performed. KL was lower at 40 weeks CA in all the SGA twin subgroups. In the SGA twins with GA >36 weeks, KL increased thereafter and became similar to AGA twins and single AGA control subjects. Among pre-term infants of GA <36 weeks, only those with BW 3rd-10th percentile experienced catch-up in KL, while in those with BW <3rd percentile, KL remained lower than in AGA infants throughout the study period, both in absolute terms and relative to other anthropometric indices. No differences in KL were found between twin SGA and singleton SGA or between twin AGA and singleton AGA infants. Intrapair BW differences were correlated with the intrapair differences in KL.


CONCLUSIONS
Twin SGA infants born prematurely with BW <3rd percentile are unable to achieve catch-up in KL in the first 24 months of life, and long-term follow-up is recommended.
Giapros
Vasileios
V
Neonatal Intensive Care Unit, University Hospital of Ioannina, Leoforos Stavrou Niarhou, Ioannina, Greece. vgiapros@cc.uoi.gr
Drougia
Aikaterini
A
Hotoura
Efthalia
E
Argyropoulou
Maria
M
Papadopoulou
Frederica
F
Andronikou
Styliani
S
D005260:Female; D005865:Gestational Age; D005919:Glomerular Filtration Rate; D006801:Humans; D007223:Infant; D007231:Infant, Newborn; D007236:Infant, Small for Gestational Age; D007668:Kidney / Q000254:growth & development*; D008297:Male; D009929:Organ Size; D012044:Regression Analysis; D014427:Twins