Department of Epidemiology, Michigan State University, East Lansing, MI 48824, USA.
Psychoneuroendocrinology. 2010 Jul;35(6):820-32. doi: 10.1016/j.psyneuen.2009.11.007. Epub 2009 Dec 16.
Corticotropin-releasing hormone (CRH) in maternal blood originates primarily from gestational tissues and elevated levels in midpregnancy have been linked to adverse pregnancy outcomes. Investigators have hypothesized that high levels of maternal stress might lead to elevated CRH levels in pregnancy. Yet a few studies have measured maternal CRH levels among subgroups of women who experience disproportionate socioeconomic disadvantage, such as African-American and Hispanic women, and found that these groups have lower CRH levels in pregnancy. Our goal was to identify maternal characteristics related to CRH levels in midpregnancy and examine which if any of these factors help to explain race differences in CRH levels.
The Pregnancy Outcomes and Community Health (POUCH) Study prospectively enrolled women at 15-27 weeks' gestation from 52 clinics in five Michigan communities (1998-2004). Data from the POUCH Study were used to examine maternal demographics, anthropometrics, health behaviors, and psychosocial factors (independent variables) in relation to midpregnancy blood CRH levels modeled as logCRHpg/ml (dependent variable). Analyses were conducted within a sub-cohort from the POUCH Study (671 non-Hispanic Whites, 545 African-Americans) and repeated in the sub-cohort subset with uncomplicated pregnancies (n=746). Blood levels of CRH and independent variables were ascertained at the time of enrollment. All regression models included week of enrollment as a covariate. In addition, final multivariate regression models alternately incorporated different psychosocial measures along with maternal demographics and weight. Psychosocial variables included measures of current depressive symptoms, perceived stress, coping style, hostility, mastery, anomie, and a chronic stressor (history of abuse as a child and adult).
In sub-cohort models, the adjusted mean log CRH level was significantly lower in African-Americans vs. non-Hispanic Whites; the difference was -0.48pg/ml (P<0.01). This difference was reduced by 21% (-0.38pg/ml, P<0.01) after inclusion of other relevant covariates. Adjusted mean log CRH levels were also lower among women with <12 years vs. >or=12 years of education (minimal difference=-0.19pg/ml, P<0.05), and among women with high levels of depressive symptoms who did not use antidepressants vs. women with lower levels of depressive symptoms and no antidepressant use (minimal difference=-0.13pg/ml, P<0.01). Log CRH levels were inversely associated with maternal weight (-0.03pg/ml per 10 pound increase, P<.05) but unrelated to smoking and all other psychosocial measures. Results were similar in the subset of women with uncomplicated pregnancies, except that lower CRH levels were also linked to higher perceived stress.
African-American women have lower blood CRH levels at midpregnancy and the race difference in CRH levels is reduced modestly after adjustment for other maternal characteristics. CRH levels were not elevated among women with high levels of perceived stress or more chronic stressors. The inverse association between CRH levels and maternal weight is likely due to a hemodilution effect. Relations among maternal CRH levels and maternal race, educational level, and depressive symptoms are difficult to explain and invite further investigation. Our results highlight a group of covariates that merit consideration in studies that address CRH in the context of pregnancy and/or post-partum complications.
母血中的促肾上腺皮质释放激素（CRH）主要来源于妊娠组织，中孕期 CRH 水平升高与不良妊娠结局有关。研究人员假设，母体压力水平升高可能导致妊娠期间 CRH 水平升高。然而，一些研究在经历不成比例的社会经济劣势的亚组妇女（如非裔美国人和西班牙裔妇女）中测量了母体 CRH 水平，发现这些群体在妊娠期间的 CRH 水平较低。我们的目标是确定与中孕期 CRH 水平相关的母体特征，并研究这些因素中是否有任何因素有助于解释 CRH 水平的种族差异。
妊娠结局和社区健康（POUCH）研究前瞻性地从密歇根州五个社区的 52 个诊所招募了 15-27 周的孕妇（1998-2004 年）。POUCH 研究的数据用于检查与中孕期血液 CRH 水平相关的母体人口统计学、人体测量学、健康行为和心理社会因素（自变量），以 logCRHpg/ml 表示（因变量）。在 POUCH 研究的亚组（671 名非西班牙裔白人，545 名非裔美国人）内进行了分析，并在无并发症妊娠的亚组（n=746）中重复了分析。在招募时确定 CRH 血水平和自变量。所有回归模型均包含招募周作为协变量。此外，最终的多元回归模型交替纳入了不同的心理社会测量方法以及母体人口统计学和体重。心理社会变量包括当前抑郁症状、感知压力、应对方式、敌意、掌握、失范和慢性应激源（儿童和成人期的虐待史）的测量。
在亚组模型中，非裔美国人和非西班牙裔白人相比，调整后的平均 log CRH 水平明显较低；差异为-0.48pg/ml（P<0.01）。纳入其他相关协变量后，这一差异减少了 21%（-0.38pg/ml，P<0.01）。与受过≥12 年教育的女性相比，受过<12 年教育的女性的调整后平均 log CRH 水平也较低（最小差异=-0.19pg/ml，P<0.05），与不使用抗抑郁药的抑郁症状水平较高的女性相比，使用抗抑郁药的抑郁症状水平较低的女性的调整后平均 log CRH 水平也较低（最小差异=-0.13pg/ml，P<0.01）。log CRH 水平与母体体重呈负相关（每增加 10 磅体重减少 0.03pg/ml，P<.05），但与吸烟和所有其他心理社会测量无关。在无并发症妊娠的亚组中，结果相似，但 CRH 水平较低也与感知压力较高有关。
非裔美国女性在中孕期的血液 CRH 水平较低，调整其他母体特征后，CRH 水平的种族差异略有降低。高感知压力或更多慢性应激源的女性的 CRH 水平并未升高。CRH 水平与母体体重之间的负相关可能是由于血液稀释效应所致。母体 CRH 水平与母体种族、教育水平和抑郁症状之间的关系很难解释，并邀请进一步调查。我们的结果突出了一组协变量，在研究妊娠和/或产后并发症背景下的 CRH 时值得考虑。
