The effects of maternal smoking and BMI on the first and second trimester human fetal kidney

Introduction The study aimed to characterise and identify phenotypic and molecular changes to the human fetal kidney in relation to either maternal smoking or pregnancy BMI status.Methods Human fetal kidneys (n = 145) were collected from elective terminations of normally progress in g pregnancies (7–20 weeks of gestation, Scottish Advanced Fetal Research Study,REC 15/NS/0123). All kidneys were weighed and whole kidney extracts prepared from 58 fetuses. Twenty-three transcripts of key renal developmental genes, renin-angiotensin system (RAS), and kidney injury markers were quantified by qPCR. Whole kidneys were processed for histomorphological analysis to assess podocyte density. Statistical analysis was performed by ANOVA, linear regression and non-parametric tests as appropriate.Results Female smoke-exposed fetuses have slightly accelerated increase in kidney weight (P = 0.037). Preliminary data show podocyte density tends to be higher in female smoke-exposed fetuses. High maternal BMI significantly increases the relative ratio of kidney weight to total fetal body weight in male fetuses (P = 0.02), but maternal BMI has no significant association with overall podocyte density. Expression of 11/23 transcripts significantly increased with fetal age, while the erythropoietin (EPO) transcript was undetectable. Renin (REN), involved in blood pressure and fluid balance control, was significantly increased in fetal male kidneys if maternal BMI was ≥25(P < 0.04).Conclusion Retarded fetal renal development is a known major contributor to hypertension and kidney diseases in adulthood. Our data show that maternal smoking and high maternal BMI are associated with phenotypic and molecular changes in fetal kidney development