The preterm prediction study: elevated cervical ferritin levels at 22 to 24 weeks of gestation are associated with spontaneous preterm delivery in asymptomatic women.
OBJECTIVE
Low serum ferritin levels correlate with low iron stores, whereas high levels are associated with an acute-phase reaction. Our objective was to determine whether elevated levels of ferritin in the genital tract may be a potent marker to identify patients at risk for spontaneous preterm delivery.


METHODS
We performed a nested case-control study involving 182 women who had spontaneous preterm delivery and 182 term control subjects matched for race, parity, and recruitment center, and selected from 2929 women enrolled in the Preterm Prediction Study of the National Institute of Child Health and Development Maternal-Fetal Medicine Units Network. Cervical fluid ferritin was measured by use of radioimmunoassay.


RESULTS
Cervical ferritin levels were significantly higher in women who subsequently had spontaneous early preterm delivery (<32 weeks, mean +/- SD, 37.7 +/- 31.1 vs 21.5 +/- 24.1 ng/mL, P =.002; and <35 weeks, 43.2 +/- 62.7 vs 28.2 +/- 36.7 ng/mL, P =.004) than in term controls. A cervical ferritin of >75th percentile in the controls (>35.5 ng/mL) was found in 52.9% (9/17) of the women delivered <29 weeks vs 17.7% (3/17) of the controls (odds ratio [OR] 5.3 [95% CI 1.1-25.2]) and in 43.5% (20/46) of the women delivered <32 weeks versus 10.9% (5/46) of the controls (OR 6.3, 95% CI 2.1-18.9). Cervical ferritin levels had a weaker association with spontaneous preterm delivery <35 weeks (OR 2.8 [95% CI 1.5-5.1]) and <37 weeks (OR 1.6, 95% CI 1.0-2.5]). Cervical ferritin levels correlated significantly with cervical lactoferrin, interleukin-6 (IL-6), and defensin levels.


CONCLUSIONS
Elevated cervical ferritin levels at 22 to 24 weeks of gestation in asymptomatic women are associated with subsequent spontaneous preterm birth. The strong correlation of cervical ferritin with other inflammatory markers provides support for the hypothesis of infection as a mediator of preterm delivery.
Ramsey
Patrick S
PS
National Institute of Child Health and Human Development, Maternal-Fetal Medicine Units Network, USA. ramsey_patrick@hotmail.com
Tamura
Tsunenobu
T
Goldenberg
Robert L
RL
Mercer
Brian M
BM
Iams
Jay D
JD
Meis
Paul J
PJ
Moawad
Atef H
AH
Das
Anita
A
Van Dorsten
J Peter
JP
Caritis
Steve N
SN
Thurnau
Gary
G
Dombrowski
Mitchell P
MP
Miodovnik
Menachem
M
D000328:Adult; D015415:Biomarkers; D016022:Case-Control Studies; D002584:Cervix Uteri / Q000378:metabolism*; D005260:Female; D005293:Ferritins / Q000378:metabolism*; D005544:Forecasting; D006801:Humans; D007231:Infant, Newborn; D007234:Infant, Premature; D007752:Obstetric Labor, Premature; D011247:Pregnancy; D011263:Pregnancy Trimester, Third; D012016:Reference Values
D015415:Biomarkers; D005293:Ferritins