Helayne M. Silver

Etiology and epidemiology of preterm premature rupture of the membranes.

Preterm premature rupture of membranes continues to be a common complication of pregnancy with significant implications for perinatal outcome. Unfortunately, given the multiple risk factors that have been presented, which are reportedly associated with PPROM, attempts to reduce the incidence of this clinical event may seem daunting to the clinician. Despite this, one should attempt to address the potential risk factors that avail themselves to change. Unfortunately, although many risk factors have been identified, there are few randomized intervention trials for PPROM prevention. Examples of interventions documented to be beneficial include smoking cessation and screening for and treatment of chlamydial infections. These seem to be reasonable and logical interventions to consider in general, and may potentially have an effect on various causal agents of PPROM.

Second-trimester levels of maternal serum human chorionic gonadotropin and inhibin a as predictors of preeclampsia in the third trimester of pregnancy.

Objective: To determine whether second-trimester maternal serum levels of inhibin A, human chorionic gonadotropin (hCG), unconjugated estriol (uE3), and alpha-fetoprotein (AFP) are predictive of the later onset of preeclampsia in pregnancy. Methods: Retrospective evaluation of serum analyte levels in 60 women with preeclampsia compared with 300 controls. Levels of each analyte were compared in women with preeclampsia and controls using matched rank analysis. Analytes that were significantly different between groups were examined with univariate and bivariate Gaussian distribution analysis. Results: Second-trimester inhibin A (1.36 multiples of the median [MoM]) and hCG (1.40 MoM) levels were significantly but modestly elevated in women who later developed preeclampsia. A combination test of maternal age plus inhibin A and hCG predicted 23% of cases of preeclampsia with 95% specificity. There was a statistically significant trend for inhibin A, but not hCG, levels to be higher when the onset of preeclampsia occurred within a shorter (< 17 weeks) interval after collection of the second-trimester streening sample. Conclusions: Second-trimester serum levels of inhibin A and hCG are modest predictors of the later onset of preeclampsia. Inhibin A may be a better predictor of early-onset preeclampsia, which is associated with a higher maternal and perinatal morbidity and mortality, than preeclampsia at or near term.

Immediate and Delayed Cord Clamping in Infants Born Between 24 and 32 Weeks: A Pilot Randomized Controlled Trial

OBJECTIVE: This pilot studys aim was to establish feasibility of a protocol for delayed cord clamping (DCC) versus immediate cord clamping (ICC) at preterm birth and to examine its effects on initial blood pressure and other outcomes.STUDY DESIGN: A randomized controlled trial recruited 32 infants between 24 and 32 weeks. Immediately before delivery, mothers were randomized to ICC (cord clamped at 5 to 10 seconds) or DCC (30- to 45-second delay in cord clamping) groups.RESULTS: Intention-to-treat analyses revealed that the DCC group were more likely to have higher initial mean blood pressures (adjusted OR 3.4) and less likely to be discharged on oxygen (adjusted OR 8.6). DCC group infants had higher initial glucose levels (ICC=36 mg/dl, DCC=73.1 mg/dl; p=0.02).CONCLUSION: The research design is feasible. The immediate benefit of improved blood pressure was confirmed and other findings deserve consideration for further study.

Mechanism of increased maternal serum total activin a and inhibin a in preeclampsia.

Objective: To determine whether increased levels of maternal serum total activin A and inhibin A in preeclampsia are related to total blood volume, urinary clearance, or placental production. Study Design: Activin A and inhibin A levels were measured in preeclamptic subjects and matched normotensive gravidas. In a subset of preeclamptic subjects (n = 21) and controls (n = 30), we performed blood volume studies. In an overlapping subject of preeclamptic subjects (n = 56), creatinine clearance results were available. Placental tissue was obtained from six preeclamptics and matched normotensive gravida for analysis of activin A and inhibin A mRNA expression. Results: Maternal serum levels of inhibin A but not activin A were significantly negatively correlated with blood volume in preeclampsia (r2 = .26, P = 0.17, and r2 = .02, P = .44, respectively). Levels of both proteins were negatively correlated to creatinine clearance (r2 = .29, P < .0001, and r2 = .15, P = .003, respectively). Placental mRNA expression for both the α and βA subunits was increased in preeclampsia (P = .038 and .049, respectively). Conclusion: Although placental mRNA expression of the subunits for both analytes is increased in preeclampsia, the increased levels of activin A appear to be more specifically a reflection of increased placental production than do the increased levels of inhibin A.

MALARIAL INFECTION DURING PREGNANCY

This article reviews the parasitology of malaria, epidemiology in pregnancy, pathogenesis of increased susceptibility to infection in pregnancy, the effect of pregnancy on the clinical manifestations of malaria, the effect of malaria on perinatal outcomes, the safety of antimalarial agents during pregnancy, the role of chemoprophylaxis for inhabitants and travelers to endemic areas, and treatment of clinical malarial infections during pregnancy.

LYME DISEASE DURING PREGNANCY

There has been great concern in the past regarding the possible fetal infection and teratogenicity from Lyme disease contracted during pregnancy because of the similarities of disease caused by Borrelia burgdorferi to syphilis. Although the initial retrospective case reports were alarming, more recent prospective data have been reassuring. This article reviews the evidence that currently supports the assurance of the benign nature of this infection with respect to the fetus.

A comparison of the yield of positive antenatal group B Streptococcus cultures with direct inoculation in selective growth medium versus primary inoculation in transport medium followed by delayed inoculation in selective growth medium

OBJECTIVE Our purpose was to compare the yield of positive group B Streptococcus cultures with standard medium for transport of culture swabs compared with use of selective medium during transport. STUDY DESIGN Cultures of introitus, perineum, and rectum were obtained on prenatal patients; one was placed in standard transport medium, and the other directly in selective growth medium. Swabs in standard transport medium were plated for routine culture and then transferred to selective growth medium, Todd-Hewitt broth, in the laboratory. RESULTS A total of 307 of 1222 (25.1%) patients had a positive result by any method. With direct inoculation into selective growth medium at the time of sampling, 4.6% of positive cultures were missed. With delayed inoculation into selective growth medium, 16.3% were missed (p < 0.001). Without use of selective media (routine culture), 31.9% were missed (p < 0.001). CONCLUSIONS Use of standard transport medium with subsequent transfer into selective growth medium results in a significantly decreased yield of positive group B Streptococcus cultures.

Red Cell Volume Determination Using a Stable Isotope of Chromium

Objective: To validate and improve a method of red cell volume determination by useof a stable isotope of chromium. Methods: Twelve subjects were sequentially injected with red blood cells labeled with a stable isotope of chromium (53 Cr) and red blood cells labeled with radioisotopic chromium (51 Cr). Measurement of 53Cr dilution was by gas chromatography/mass spectrometry. Measurement of 51Cr dilution was by gamma counter. Results: Comparison of the two methods let to results that differed on average by 34.5 ± 45.0 mL (1.8 ± 2.2%), 0.3 to 3.2%, 95% confidence interval. Conclusion: Measurement of red cell volume by use of a stable isotope of chromium is accurate, with potential applications including measurement in pregnant women and children or other groups in whom exposure to radioisotopes is undesirable.