Racial variation in umbilical cord blood sex steroid hormones and the insulin-like growth factor axis in African-American and white female neonates

Abstract

Purpose To evaluate whether there is racial variation in venous umbilical cord blood concentrations of sex steroid hormones and the insulin-like growth factor (IGF)-axis between female African-American and white neonates. Methods Maternal and birth characteristics and venous umbilical cord blood samples were collected from 77 African-American and 41 white full-term uncomplicated births at two urban hospitals in 2004 and 2005. Cord blood was measured for testosterone, dehydroespiandrosterone-sulfate (DHEAS), estradiol, sex-steroid hormone binding globulin (SHBG) by immunoassay. IGF-1, IGF-2, and IGF binding protein-3 (IGFBP-3) were measured by ELISA. Crude and multivariable-adjusted geometric mean concentrations were computed for the hormones. Results African-American neonates weighed less at birth (3,228 vs. 3,424 grams, p<0.004) than whites. Birth weight was positively correlated with IGF-1, IGFBP-3 and the molar ratio of IGF1 to IGFBP-3, but inversely correlated with the molar ratio of IGF-2 to IGFBP-3. Adjusted models showed higher testosterone (1.82 vs. 1.47 ng/mL, p=0.006) and the molar ratio of testosterone to SHBG (0.42 vs. 0.30, p=0.03) in African-American compared to white female neonates. IGF-1, IGF-2, and IGFBP-3 were lower in African-American compared to white female neonates, but only the difference for IGF-2 remained significant (496.5 vs. 539.2 ng/mL, p=0.04). Conclusion We provide evidence of racial variation in cord blood testosterone and testosterone to SHBG in African-American compared to white female neonates, and higher IGF-2 in white compared to African-American female neonates. Findings suggest plausible explanations for a prenatal influence on subsequent breast cancer risk and mortality. Further work is needed to confirm these observations.

Maternal BMI, IGF-I Levels, and Birth Weight in African American and White Infants

“…The main limitation of this study was relatively small sample size for analyses restricted to maternal BMI (BMI < 30 versus BMI ≥ 30); however, findings are consistent with the expected role of IGF-I, and IGF-I values themselves (range, median, and skewness of IGF-I levels) and the magnitude of the positive associations with higher birth weight and growth are similar to previous reports [25, 26]. Also, we relied on a single measure of IGF-I levels at delivery; however it was not feasible to obtain IGF-I levels before birth in these infants.…”

“…These race/ethnic similarities exist despite IGF-I concentrations being generally lower in African American than in White neonates born with normal weight, as shown in male [25] and in female newborns [26], and in studies performed in adults [33]. …”

“…Several lines of evidence suggest that IGF-I levels are associated with birth weight [15–26]; furthermore higher IGF-I levels are associated with higher BW, but not with lower birth weight [16, 17, 26]. In adulthood, elevated concentrations of IGF-I are associated with an increased risk of obesity and many cancers, including breast, lung, head and neck, colorectal, pancreas, synovial sarcoma, and prostate cancer [26–31]. Although concentrations of circulating IGF-I levels vary considerably by race/ethnicity and maternal prepregnancy obesity, few studies included African American women [24–26], an ethnic group that has an almost 9% higher BMI than European-American women [32].…”

“…In adulthood, elevated concentrations of IGF-I are associated with an increased risk of obesity and many cancers, including breast, lung, head and neck, colorectal, pancreas, synovial sarcoma, and prostate cancer [26–31]. Although concentrations of circulating IGF-I levels vary considerably by race/ethnicity and maternal prepregnancy obesity, few studies included African American women [24–26], an ethnic group that has an almost 9% higher BMI than European-American women [32]. Furthermore, studies examining both maternal obesity, an increasingly common condition, and race/ethnicity are few [33–35].…”

Androgens in maternal vascular and placental function: implications for preeclampsia pathogenesis

“…Ethnicity has also been implicated in contributing hyperandrogenism-related preeclampsia. Pregnant African-American women exhibit high maternal testosterone levels (120–130%), including elevated fetal cord blood testosterone levels at term ( Henderson et al 1988 , Potischman et al 2005 , Rohrmann et al 2009 , Agurs-Collins et al 2012 ) and are at increased risk for developing preeclampsia ( Samadi et al 2001 , Iavazzo & Vitoratos 2010 ). In addition, plasma testosterone levels are increased during pregnancy in a variety of situations ( Fig.…”