Relationship between birth weight, glomerular number, and glomerular size

Association between early exposure to famine and risk of renal impairment in adulthood: a systematic review and meta-analysis

Malnutrition early in life increases the later-life risk of noncommunicable diseases, and previous epidemiologic studies have found a link between famine and renal impairment, but no consensus has been reached. This meta-analysis and systematic review were conducted to assess the correlation between early-life famine exposure and the risk of developing renal impairment. Search in Embase, Scopus, Web of Science, PubMed, and Cochrane using keywords that report the correlation between early famine exposure and renal function indicators. RevMan and Stata software were used for data analysis. This meta-analysis contained twelve observational studies. The findings demonstrated a link between prenatal famine exposure and a higher risk of developing chronic kidney disease (CKD) (odds ratio (OR) = 1.73, 95% confidence interval (CI): 1.25, 2.39), a decreased estimated glomerular filtration rate (eGFR) (mean difference (MD) = -10.05, 95% CI: -11.64, -8.46), and increased serum creatinine (Scr) (MD = 0.02, 95% CI: 0.01, 0.03) compared to unexposed individuals. Famine exposure in childhood was associated with decreased eGFR (MD = -9.43, 95% CI: -12.01, -6.84) and increased Scr (MD = 0.03, 95% CI: 0.01, 0.04), but not with CKD (OR = 0.980, 95% CI: 0.53, 1.81). Famine exposure in adolescence and adulthood was associated with decreased eGFR (MD = -20.73, 95% CI: -22.40, -19.06). Evidence certainty was deemed to be of low or extremely low quality. Famine exposure early in life could pose a greater risk of developing renal impairment in adulthood, but this outcome may be driven by uncontrolled age differences between famine-births and post-famine-births (unexposed).

Sex differences in the fetal programming of hypertension

BACKGROUND

Numerous clinical and experimental studies support the hypothesis that the intrauterine environment is an important determinant of cardiovascular disease and hypertension.

OBJECTIVE

This review examined the mechanisms linking an adverse fetal environment and increased risk for chronic disease in adulthood with an emphasis on gender differences and the role of sex hormones in mediating sexual dimorphism in response to a suboptimal fetal environment.

METHODS

This review focuses on current findings from the PubMed database regarding animal models of fetal programming of hypertension, sex differences in phenotypic outcomes, and potential mechanisms in offspring of mothers exposed to an adverse insult during gestation. For the years 1988 to 2007, the database was searched using the following terms: fetal programming, intrauterine growth restriction, low birth weight, sex differences, estradiol, testosterone, high blood pressure, and hypertension.

RESULTS

The mechanisms involved in the fetal programming of adult disease are multifactorial and include alterations in the regulatory systems affecting the long-tterm control of arterial pressure. Sex differences have been observed in animal models of fetal programming, and recent studies suggest that sex hormones may modulate activity of regulatory systems, leading to a lower incidence of hypertension and vascular dysfunction in females compared with males.

CONCLUSIONS

Animal models of fetal programming provide critical support for the inverse relationship between birth weight and blood pressure. Experimental models demonstrate that sex differences are observed in the pathophysiologic response to an adverse fetal environment. A role for sex hormone involvement is strongly suggested,with modulation of the renin-angiotensin system as a possible mechanism.

Growth patterns of the heart and kidney suggest inter-organ collaboration in facultative fetal growth

Maternal smoking during pregnancy has been associated with a number of negative sequelae among offspring, including elevated postnatal blood pressure. While animal studies have described organ level alterations with smoke exposure, human data have been more limited. Thirty-four healthy maternal/fetal pairs (24 nonsmokers, 10 smokers) participated in a longitudinal growth study from the thirteenth week of pregnancy to document fetal kidney and heart growth trajectories and morphology. Curve fitting followed by a mixed model for repeated measures identified significantly different growth patterns in kidney width, thickness, length, and volume growth with exposure: the smoke-exposed fetal kidney was wide and thick compared to the unexposed kidney during the second and early third trimester, declining to proportionately thin kidneys for length and width subsequently. Cardiac growth in width and volume followed a reverse pattern: a surge in cardiac volume occurred after 30 weeks with acceleration in cardiac width, resulting in a heart that was wide for length and for fetal weight. Smoke exposure altered fetal growth in size and timing of the heart and kidneys during midgestation, with changes in organ morphology suggesting compensatory growth. These are the first data providing anatomical evidence of altered renal/cardiac volume relationships that may provide a mechanism to previously reported sequelae of in utero smoke exposure. They suggest that cell-level adaptive responses to hypoxia and/or chemical insults are operative and illustrate the importance of longitudinal ultrasound to directly assess the organ-level growth response of the human fetus to a prenatal stress, in lieu of relying on birth outcome measures.

Infants thinner at birth exhibit smaller kidneys for their size in late gestation in a sample of fetuses with appropriate growth

Fetal ultrasound measurements were employed to investigate the relationship between weight and ponderal index at birth and kidney size during the second (23 weeks) and third (32 weeks) trimesters of pregnancy in a sample of 25 normally growing fetuses. Kidney volume and kidney volume / fetal weight ratio at 32 weeks are significantly and positively related to both weight and ponderal index at birth, controlling for sex, gestational age at birth, and day of ultrasound measurement. A second-degree polynomial relationship approximates the predictability of kidney volume fetal weight ratio at 23 weeks to that at 32 weeks, demonstrating shifting growth rates in fetal organ and body growth relationships during midgestation. Sex and parental size are suggested as contributing to these patterns. Females have a surge in renal growth between 23 and 32 weeks to catch up to earlier growing males, and maternal weight significantly predicts incremental growth in kidney volume and the kidney volume / fetal weight ratio at 32 weeks of gestation. The observation that fetuses relatively thin at birth have relatively smaller kidneys for their size in late gestation suggests that the influence of maternal weight on birth outcome may act through organ growth.