Second trimester corticotropin-releasing hormone levels in relation to preterm delivery and ethnicity.
OBJECTIVE
To assess the relationship between maternal corticotropin-releasing hormone (CRH) levels in second trimester sera, and the risk of preterm delivery in an ethnically heterogeneous sample of pregnant women.


METHODS
This nested case-control study included two case groups (97 women who delivered before 35 weeks' gestation, 144 who delivered at 35--36 weeks' gestation), and a control group (244 women who delivered at or after 37 weeks' gestation) frequency matched by ethnicity (black, white) and by alpha-fetoprotein levels (normal, unexplained high). Corticotropin-releasing hormone was evaluated in stored maternal sera collected at 15--19 weeks' gestation from cases and controls.


RESULTS
Delivery before 35 weeks' gestation was associated positively with a second trimester, ethnic-specific CRH above 1.5 multiples of the median in white women [odds ratio (OR) 2.3, 95% confidence interval (CI) 1.1, 5.1] and black women (OR 5.0, 95% CI 1.8, 13.3). Sensitivity was 29% in whites and 41% in blacks; specificity was 84% in whites and 80% in blacks. We estimated the positive and negative predictive values to be 6% and 97%, respectively, in white women, and 16% and 93%, respectively, in black women. It was also noted that, within case and control groups, black women had consistently lower CRH levels than white women.


CONCLUSIONS
Factors that lead to a premature increase in placental CRH production and are associated with an increased risk of preterm birth are evident as early as 15--19 weeks' pregnancy. When considering potential links between stressors, placental changes, CRH levels, and preterm birth, it might be important to stratify or adjust for ethnicity.
Holzman
C
C
Department of Epidemiology, Michigan State University, East Lansing, Michigan 48823, USA. holzman@msu.edu
Jetton
J
J
Siler-Khodr
T
T
Fisher
R
R
Rip
T
T
D000328:Adult; D015415:Biomarkers / Q000032:analysis; D044383:Black People; D016022:Case-Control Studies; D015331:Cohort Studies; D003346:Corticotropin-Releasing Hormone / Q000032:analysis*; D005260:Female; D006801:Humans; D015994:Incidence; D008403:Mass Screening / Q000379:methods*; D007752:Obstetric Labor, Premature / Q000175:diagnosis / Q000208:ethnology* / Q000378:metabolism; D011247:Pregnancy; D011256:Pregnancy Outcome; D011262:Pregnancy Trimester, Second; D011336:Probability; D012016:Reference Values; D018570:Risk Assessment; D012494:Sampling Studies; D012680:Sensitivity and Specificity; D044465:White People
D015415:Biomarkers; D003346:Corticotropin-Releasing Hormone