miR-34a is a tumor suppressor in zebrafish and its expression levels impact metabolism, hematopoiesis and DNA damage.

Li-Fraumeni syndrome is caused by inherited TP53 tumor suppressor gene mutations. MicroRNA miR-34a is a p53 target and modifier gene. Interestingly, miR-34 triple-null mice exhibit normal p53 responses and no overt cancer development, but the lack of miR-34 promotes tumorigenesis in cancer-susceptible backgrounds. miR-34 genes are highly conserved and syntenic between zebrafish and humans. Zebrafish miR-34a and miR-34b/c have similar expression timing in development, but miR-34a is more abundant. DNA damage by camptothecin led to p53-dependent induction of miR-34 genes, while miR-34a mutants were adult-viable and had normal DNA damage-induced apoptosis. Nevertheless, miR-34a-/- compound mutants with a gain-of-function tp53R217H/ R217H or tp53-/- mutants were more cancer-prone than tp53 mutants alone, confirming the tumor-suppressive function of miR-34a. Through transcriptomic comparisons at 28 hours post-fertilization (hpf), we characterized DNA damage-induced transcription, and at 8, 28 and 72 hpf we determined potential miR-34a-regulated genes. At 72 hpf, loss of miR-34a enhanced erythrocyte levels and up-regulated myb-positive hematopoietic stem cells. Overexpression of miR-34a suppressed its reporter mRNA, but not p53 target induction, and sensitized injected embryos to camptothecin but not to γ-irradiation.

1,5-ANHYDROGLUCITOL AND NEONATAL COMPLICATIONS IN PREGNANCY COMPLICATED BY DIABETES.

OBJECTIVE: To determine the association of 1,5-anhydroglucitol (1,5-AG) with neonatal birth weight (NBW) and neonatal hypoglycemia (+NH) in pregnancies complicated by diabetes. METHODS: We assessed a retrospective cohort of 102 females, 17 with gestational diabetes (GDM), 48 with type 1 diabetes mellitus (T1DM), and 37 with type 2 diabetes mellitus (T2DM). 1,5-AG and glycated hemoglobin A1C (A1C) values throughout pregnancy were extracted. Linear regression was used to assess their association with NBWs z-scores adjusting for maternal age, ethnicity and body mass index (BMI). +NH was defined by a note in the infant record, glucose <1.7 mmol/L in the first 24 h, or <2.5 mmol/L in the first 48 h after birth. A t test or Welch's approximate t test was used to compare the mean 1,5-AG and A1C of mothers with +NH versus those without (-NH), adjusted for gestational age and analyzed by diabetes type and across trimesters. RESULTS: Mean 1,5-AG significantly differed across groups: T1DM 3.77 ± 2.82 µg/mL, T2DM 5.73 ± 4.38 µg/mL, GDM 8.89 ± 4.39 µg/mL (P<.0001), suggesting less glucose exposure in GDM relative to T1DM or T2DM. A negative linear association was found between mean 1,5-AG and z-scores (R= -0.28, P = .005. In contrast, the association between mean A1C and z-scores was weaker (R = 0.15, P = .14). The mean 1,5-AG tended to be lower in the +NH cohort versus -NH (P = .08), and this was statistically significant (P = .01) among subjects with GDM. CONCLUSION: The association of 1,5-AG with complications related to glycemic exposure supports the notion of its utility as an adjunct glycemic biomarker in pregnancies complicated by diabetes and across trimesters.

Genital HSV detection among HIV-1-infected pregnant women in labor.

OBJECTIVE: To compare genital HSV shedding among HIV-positive and HIV-negative women. METHODS: Women with and without known HIV infection who delivered at the University of Washington Medical Center between 1989-1996 had HSV serologies done as part of clinical care. Genital swabs from HSV-2-seropositive women were evaluated by real-time quantitative HSV DNA PCR. RESULTS: HSV-2 seroprevalence was 71% and 30% among 75 HIV-positive and 3051 HIV-negative women, respectively, (P < .001). HSV was detected at delivery in the genital tract of 30.8% of HIV-seropositive versus 9.5% of HIV-negative women (RR = 3.2, 95% CI 1.6 to 6.5, P = .001). The number of virion copies shed per mL was similar (log 3.54 for HIV positive versus 3.90 for HIV negative, P = .99). CONCLUSIONS: Our study demonstrated that HIV-, HSV-2-coinfected women are more likely to shed HSV at delivery.

Pharmacodynamics of Metformin in Pregnant Women With Gestational Diabetes Mellitus and Nonpregnant Women With Type 2 Diabetes Mellitus.

Gestational diabetes mellitus is a condition similar to type 2 diabetes mellitus (T2DM) in that patients are unable to compensate for the degree of insulin resistance, and both conditions are often treated with metformin. The comparative pharmacodynamic response to metformin in these 2 populations has not been studied. This study characterized insulin sensitivity, ß-cell responsivity, and disposition index following a mixed-meal tolerance test utilizing a minimal model of glucose, insulin, and C-peptide kinetics before and during treatment with metformin. The study included women with gestational diabetes mellitus (n = 34), T2DM (n = 14), and healthy pregnant women (n = 30). Before treatment, the gestational diabetes mellitus group had significantly higher baseline (45%), dynamic (68%), static (71%), and total ß-cell responsivity (71%) than the T2DM group. Metformin significantly increased insulin sensitivity (51%) as well as disposition index (97%) and decreased mixed-meal tolerance test peak glucose concentrations (8%) in women with gestational diabetes mellitus after adjustment for gestational age-dependent effects; however, in women with T2DM metformin only significantly affected peak glucose concentrations (22%) and had no significant effect on any other parameters. Metformin had a greater effect on the change in disposition index (Δ disposition index) in women with gestational diabetes mellitus than in those with T2DM (P = .01). In conclusion, response to metformin in women with gestational diabetes mellitus is significantly different from that in women with T2DM, which is likely related to the differences in disease severity.

Pharmacodynamics of Glyburide, Metformin, and Glyburide/Metformin Combination Therapy in the Treatment of Gestational Diabetes Mellitus.

In gestational diabetes mellitus (GDM), women are unable to compensate for the increased insulin resistance during pregnancy. Data are limited regarding the pharmacodynamic effects of metformin and glyburide during pregnancy. This study characterized insulin sensitivity (SI), ß-cell responsivity, and disposition index (DI) in women with GDM utilizing a mixed-meal tolerance test (MMTT) before and during treatment with glyburide monotherapy (GLY, n = 38), metformin monotherapy (MET, n = 34), or GLY and MET combination therapy (COMBO; n = 36). GLY significantly decreased dynamic ß-cell responsivity (31%). MET and COMBO significantly increased SI (121% and 83%, respectively). Whereas GLY, MET, and COMBO improved DI, metformin (MET and COMBO) demonstrated a larger increase in DI (P = 0.05) and a larger decrease in MMTT peak glucose concentrations (P = 0.03) than subjects taking only GLY. Maximizing SI with MET followed by increasing ß-cell responsivity with GLY or supplementing with insulin might be a more optimal strategy for GDM management than monotherapy.

Managing genital herpes infections in pregnancy.

Genital herpes is common and is becoming more so, with a seroprevalence of 25% in middle class primary care settings. Primary genital herpes in pregnancy most often is subclinical, but it also can cause severe illness. Further, active genital herpes at the time of vaginal delivery poses significant risk of neonatal infection, especially if the mother acquired the infection in the third trimester. It is important to prevent genital herpes acquisition in pregnancy and to diagnose recurrent genital herpes to prevent neonatal herpes.

Managing varicella zoster infection in pregnancy.

Varicella zoster virus (VZV) infection can be serious for pregnant women and their babies, although it is rare. The implications of primary VZV infection vary with the gestational age at infection. For the mother, the risk of severe illness is greatest after mid-pregnancy, when she is relatively immunocompromised. For the fetus, the risk of congenital infection is greatest when maternal infection occurs in the first or second trimester. Maternal infection is preventable by preconception vaccination.

Diabetic nephropathy in pregnancy: suboptimal hypertensive control associated with preterm delivery.

BACKGROUND: Nephropathy complicates 5% to 10% of pregnancies in women with diabetes and is associated with adverse outcomes. Given the importance of blood pressure (BP) control in reducing cardiovascular and renal complications outside of pregnancy, we hypothesized that poorly controlled hypertension in early pregnancy among women with diabetic nephropathy would be associated with adverse outcomes. METHODS: To examine the impact of hypertensive control in early pregnancy on perinatal outcomes, we performed a retrospective cohort study of pregnancies complicated by diabetic nephropathy with "Above Target" mean arterial pressure (> or = 100 mm Hg; N = 21) and "Below Target" mean arterial pressure (< 100 mm Hg; N = 22), which approximates the American Diabetes Association and the Seventh Report of the Joint National Committee recommended target of 130/80 mm Hg, measured at < 20 weeks' gestation. RESULTS: There were no differences in maternal age (mean +/- SEM: 27.2 +/- 1.2 v 29.5 +/- 1.0 years), duration of diabetes (median, range: 17.5, 13 to 24 v 16, 1 to 25 years), or glucose control (glycosylated hemoglobin [HbA1c] 8.0% +/- 0.3% v 8.1% +/- 0.4%) between the Above and Below Target groups. The Above Target group had more proteinuria (4.69 +/- 1.08 v 1.65 +/- 0.43 g/24 h; P = .007) and higher serum creatinine levels (1.23 +/- 0.17 v 0.85 +/- 0.06 mg/dL; P = .02). The Above Target group was more likely to deliver at < 32 weeks' gestation (38.1% v 4.6%; P = .007). The increased risk of preterm delivery remained significant after adjusting for duration of diabetes and glucose control. CONCLUSIONS: Suboptimal control of hypertension in early pregnancy in women with diabetic nephropathy is associated with a significant risk of preterm delivery. Improved preconceptional control of hypertension may reduce adverse perinatal outcomes in women with diabetic nephropathy.

Genital herpes complicating pregnancy.

Approximately 22% of pregnant women are infected with herpes simplex virus (HSV)-2, and 2% of women will acquire HSV during pregnancy. Remarkably, up to 90% of these women are undiagnosed because they are asymptomatic or have subtle symptoms attributed to other vulvovaginal disorders. Diagnosis of genital herpes relies on laboratory confirmation with culture or polymerase chain reaction assay of genital lesions and type-specific glycoprotein G-based serologic testing. Neonatal herpes is the most severe complication of genital HSV infection and is caused by contact with infected genital secretions at the time of labor. Maternal acquisition of HSV in the third trimester of pregnancy carries the highest risk of neonatal transmission. Despite advances in the diagnosis and treatment of neonatal herpes, little change in the incidence or serious sequelae from this infection has occurred. As such, prevention of the initial neonatal infection is critically important. Obstetricians are in a unique position to prevent vertical HSV transmission by identifying women with genital lesions at the time of labor for cesarean delivery, prescribing antiviral suppressive therapy as appropriate, and avoiding unnecessary invasive intrapartum procedures in women with genital herpes. Enhanced prevention strategies include identification of women at risk for HSV acquisition during pregnancy by testing women and possibly their partners for HSV antibodies and providing counseling to prevent transmission to women in late pregnancy.

Poor correlation between genital lesions and detection of herpes simplex virus in women in labor.

OBJECTIVE: To estimate the accuracy of clinical diagnosis of genital herpes for herpes simplex virus (HSV) detection among women in labor. METHODS: Viral detection by culture and HSV DNA polymerase chain reaction (PCR) among women who underwent cesarean delivery for genital herpes was compared with women without HSV symptoms in labor who had genital swabs collected for HSV culture and to a subset of these women who had genital specimens available for PCR analysis, regardless of culture results. RESULTS: From 1989 to 1999, 126 of 19,568 (0.6%) women underwent cesarean delivery for HSV. Twenty-six percent of 110 of these women had HSV detected by culture from at least 1 genital specimen and 46% of 70 of these women had HSV detected by PCR. During the same period, 61 of 12,623 (0.5%) asymptomatic women had HSV detected by culture. Between 1995 and 1996, 57 of 2,109 (2.7%) asymptomatic women had HSV detected by PCR. Thus, the presence of genital lesions had a sensitivity for HSV detection of 37% by culture and 41% by PCR. The amount of HSV present in asymptomatic women with HSV detected in genital secretions by PCR was often as high as those with genital lesions, although the median amount of HSV DNA detected was greater in women with lesions. CONCLUSION: Clinical diagnosis of genital herpes at the time of labor correlates relatively poorly with HSV detection from genital sites or lesions by culture or PCR and fails to identify asymptomatic women who have HSV in their genital secretions at the time of labor.

Risk factors for herpes simplex virus transmission to pregnant women: a couples study.

OBJECTIVE: This study was undertaken to determine risk factors for herpes simplex virus (HSV) acquisition among at risk pregnant women. STUDY DESIGN: Women in a prospective study of HSV acquisition in pregnancy invited their sexual partners for HSV type-specific serologic testing. Risk factors for HSV susceptibility, exposure, and acquisition were examined. RESULTS: A total of 3192 couples enrolled; 22% included women at risk for HSV-1 or HSV-2. Among 582 HSV-1 seronegative women with HSV-1 seropositive partners, 14 (3.5% adjusted for gestation length) acquired HSV-1. Having a partner with a history of oral herpes was associated with HSV-1 acquisition (odds ratio [OR] 8.1, 95% CI: 1.8-36.0) and accounted for 75% of incident infections. Among 125 HSV-2 seronegative women with HSV-2 seropositive partners, 17 (20% adjusted for gestation length) acquired HSV-2. Duration of partnership of 1 year or less was associated with HSV-2 acquisition (OR 7.8, 95% CI: 2.3-25.7) and accounted for 63% of incident infections. No combination of clinical characteristics could identify the majority of susceptible women with serologically discordant partners. CONCLUSION: HSV acquisition rates in pregnancy are high in discordant couples, especially for HSV-2. Interventions that address risk factors for HSV acquisition should be studied in pregnancy. Clinical profiles cannot replace serologic screening to identify susceptible women with serologically discordant partners.

1,5-Anhydroglucitol: a new predictor of neonatal birth weight in diabetic pregnancies.

OBJECTIVE: To determine whether 1,5-anhydroglucitol is predictive of neonatal birth weight. STUDY DESIGN: A retrospective cohort study including 85 pregnancies complicated by diabetes (Type 1=37, Type 2=24, gestational=24). Women had simultaneous hemoglobin A1c and 1,5-anhydroglucitol measurements every 4-8 weeks throughout pregnancy until delivery. Neonatal birth weight was evaluated by standardized z-scores. Linear regression analysis was performed to determine an association of 1,5-anhydroglucitol with neonatal birth weight z-score. RESULTS: Type 1 diabetic patients had the lowest mean 1,5-anhydroglucitol of 3.5mcg/mL (SD=1.6mcg/mL) and highest mean hemoglobin A1c of 6.5% (SD=0.74%) compared to gestational diabetic patients who had the highest mean 1,5-anhydroglucitol of 6.7mcg/mL (SD=3.8mcg/mL) and lowest mean hemoglobin A1c of 6.0% (SD=0.94%). Mean 1,5-anhydroglucitol values were significantly different between diabetes types (p<0.01). Mean neonatal birth weight was above population averages for all diabetes classifications, although mean birth weight z-scores did not differ significantly between diabetic types (p=0.38). Multivariate linear regression showed a negative association between log-transformed 1,5-anhydroglucitol and birth weight (coefficient -0.82, 95% CI -1.19, -0.46). CONCLUSION: In pregnancies complicated by diabetes, low 1,5-anhydroglucitol was associated with increased neonatal birth weight. 1,5-Anhydroglucitol may be useful in the assessment of glycemic control in pregnancy in addition to A1c.

Effect of maternal herpes simplex virus (HSV) serostatus and HSV type on risk of neonatal herpes.

BACKGROUND: Neonatal herpes simplex virus (HSV) is a rare but devastating disease. We have conducted pooled analyses of data from 3 cohorts to evaluate the effects of maternal HSV serostatus and HSV type on risk of neonatal HSV acquisition and severity. METHODS: Data from cohorts in Seattle, WA, and Stanford, CA, USA, and Stockholm, Sweden were pooled using Mantel-Haenszel methods. RESULTS: Seventy-eight infants with documented neonatal HSV and known maternal HSV serostatus were included. The risk of neonatal HSV-2 infection was similar in infants born to HSV seronegative women compared with HSV-1 seropositive women (pooled OR: 1.6; 95% CI: 0.6-4.0). The odds of neonatal HSV infection was increased in the presence of exposure to maternal HSV-1 versus HSV-2 (adjusted pooled OR: 19.2; 95% CI: 5.8-63.6). An elevated odds of disseminated HSV in infants born to women with newly acquired genital herpes was observed in Stockholm (OR=13.5; 95% CI: 1.4-630), but not in Seattle or Stanford. CONCLUSION: Our results suggest that maternal HSV-1 antibody offers little, if any, protection against neonatal HSV-2 infection. During reactivation, HSV-1 appears more readily transmissible to the neonate than HSV-2, a concerning finding given the rising frequency of genital HSV-1 infection.

Common use of inaccurate antibody assays to identify infection status with herpes simplex virus type 2.

In recent proficiency testing of herpes simplex virus type-specific serologic evidence by the College of American Pathologists, commercially available herpes simplex virus antibody assays that were not glycoprotein-G based demonstrated high false-positive rates (14%-88%) for herpes simplex virus type-2 antibodies in sera that were positive for herpes simplex virus type-1 antibodies but negative for herpes simplex virus type-2 antibodies. Herpes simplex virus serologic testing should be performed with only glycoprotein-G-based tests.

Neonatal herpes should be a reportable disease.

Neonatal herpes is a devastating disease, the most serious complication of genital herpes, one of the most common serious congenital or perinatal infections, and the most frequent complication of sexually transmitted infections among children. Nevertheless, neonatal herpes is not reportable to health authorities in most states. The potential for prevention has been enhanced by recent diagnostic and therapeutic advances, and the disease meets widely accepted criteria for reporting, including incidence rates that exceed those of comparable conditions, epidemiologic instability, disease severity, direct and indirect socioeconomic costs, concern by persons at risk, the potential for prevention by public health interventions, and the prospect that the resulting data would influence public health policy. The absence of national surveillance contributes to beliefs by healthcare providers and the public health community that genital and neonatal herpes are uncommon conditions that affect small segments of society, beliefs that directly interfere with prevention. Neonatal herpes should be a reportable condition.

Preventing herpes simplex virus transmission to the neonate.

Neonatal herpes simplex virus (HSV) infection can have severe consequences. Skin, eye and mouth infection is rarely fatal, but disseminated or central nervous system (CNS) disease has a mortality rate of 80% in the absence of therapy, and most surviving infants have neurological sequelae. Aciclovir therapy can improve the outcome of neonatal herpes, but is often delayed due to the early non-specific symptoms of the disease. Even with early therapy, some infants develop disseminated infection or CNS complications. The virus is usually vertically transmitted to the neonate from an infected mother during delivery. As such, the optimal strategy for reducing the morbidity of neonatal herpes is to prevent the neonate from acquiring HSV infection at delivery. The highest risk of neonatal infection occurs when the mother sheds HSV at labour, which happens more frequently in women who acquire genital herpes in the third trimester. Therefore, one approach for reducing maternal-fetal transmissions is to prevent HSV acquisition in late pregnancy. Definitive classification of genital HSV infection during pregnancy as either primary, non-primary first episode or recurrent can be accomplished only when clinical evaluation is accompanied by laboratory testing, including the use of gG-specific serological tests. The serological status of the mother's sexual partner should be considered when determining her risk of infection. The use of weekly viral cultures in pregnant women with confirmed genital herpes is not warranted, as they do not predict an infant's risk of acquisition of HSV at delivery and are not cost-effective. High-risk susceptible women should be counselled about abstinence and reducing oral-genital contact near term. Observational studies suggest that caesarean section can reduce transmission of neonatal herpes, and is warranted for women who shed HSV at delivery, although different countries vary in their approach to caesarean sections and so universal recommendations are not available. If maternal antiviral therapy is considered, the potential benefits of treatment should be balanced against potential adverse outcomes for mother and fetus, although it may be warranted when the mother has severe or life-threatening disease. Studies on the use of antiviral prophylaxis in women with known recurrences at labour are ongoing. Invasive fetal monitoring can increase the risk of neonatal herpes, and should only be used in HSV-2 seropositive women for defined obstetrical indications.

Case study: type-specific HSV serology and the correct diagnosis of first-episode genital herpes during pregnancy.

It is now known that the physical presentation of genital herpes simplex (HSV) infection can be misleading in making the diagnosis of genital herpes. An incorrect diagnosis can be particularly damaging in pregnancy where it may result in extended exposure of the fetus to antiviral agents, an inappropriate route and timing of delivery and a significant increase in fetal exposure to HSV during labour and delivery. Case 1 describes a 32-year-old woman at 30 weeks in her first pregnancy who had the appearance and clinical course typically ascribed to primary genital HSV infection. In contrast, Case 2, a 24-year-old woman at 34 weeks' gestation, had the physical appearance of a recurrent episode. Type-specific serological testing revealed that what Case 1 was actually experiencing was the first symptomatic reactivation of genital herpes, whereas Case 2 had a true primary genital HSV-2 infection that was accompanied by minimal symptoms. Had serology testing not been available, Case 1 would probably have delivered unnecessarily by Caesarean section, and Case 2 would have been managed as a recurrent infection and allowed to deliver vaginally with potentially disastrous results. These cases illustrate the usefulness of a type-specific serology in diagnosing genital herpes in pregnant women.

Effect of serologic status and cesarean delivery on transmission rates of herpes simplex virus from mother to infant.

CONTEXT: Neonatal herpes most commonly results from fetal exposure to infected maternal genital secretions at the time of delivery. The risk of transmission from mother to infant as it relates to maternal herpes simplex virus (HSV) serologic status and exposure to HSV in the maternal genital tract at the time of labor has not been quantified. Furthermore, no data exist on whether cesarean delivery, the standard of care for women with genital herpes lesions at the time of delivery, reduces HSV transmission. OBJECTIVE: To determine the effects of viral shedding, maternal HSV serologic status, and delivery route on the risk of transmission of HSV from mother to infant. DESIGN: Prospective cohort of pregnant women enrolled between January 1982 and December 1999. SETTINGS: A university medical center, a US Army medical center, and 5 community hospitals in Washington State. PATIENTS: A total of 58 362 pregnant women, of whom 40 023 had HSV cultures obtained from the cervix and external genitalia and 31 663 had serum samples tested for HSV. MAIN OUTCOME MEASURE: Rates of neonatal HSV infection. RESULTS: Among the 202 women from whom HSV was isolated at the time of labor, 10 (5%) had neonates with HSV infection (odds ratio [OR], 346; 95% confidence interval [CI], 125-956 for neonatal herpes when HSV was isolated vs not isolated). Cesarean delivery significantly reduced the HSV transmission rate among women from whom HSV was isolated (1 [1.2%] of 85 cesarean vs 9 [7.7%] of 117 vaginal; OR, 0.14; 95% CI, 0.02-1.08; P =.047). Other risk factors for neonatal HSV included first-episode infection (OR, 33.1; 95% CI, 6.5-168), HSV isolation from the cervix (OR, 32.6; 95% CI, 4.1-260), HSV-1 vs HSV-2 isolation at the time of labor (OR, 16.5; 95% CI, 4.1-65), invasive monitoring (OR, 6.8; 95% CI, 1.4-32), delivery before 38 weeks (OR, 4.4; 95% CI, 1.2-16), and maternal age less than 21 years (OR, 4.1; 95% CI, 1.1-15). Neonatal HSV infection rates per 100 000 live births were 54 (95% CI, 19.8-118) among HSV-seronegative women, 26 (95% CI, 9.3-56) among women who were HSV-1-seropositive only, and 22 (95% CI, 4.4-64) among all HSV-2-seropositive women. CONCLUSION: Neonatal HSV infection rates can be reduced by preventing maternal acquisition of genital HSV-1 and HSV-2 infection near term. It can also be reduced by cesarean delivery and limiting the use of invasive monitors among women shedding HSV at the time of labor.

A double-blind, randomized, placebo-controlled trial of acyclovir in late pregnancy for the reduction of herpes simplex virus shedding and cesarean delivery.

OBJECTIVE: The purpose of this study was to assess the efficacy of acyclovir in the reduction of herpes simplex virus culture and polymerase chain reaction positivity and cesarean delivery. STUDY DESIGN: Women with recurrent genital herpes simplex virus were randomized to acyclovir 400 mg three times daily or placebo from 36 weeks of gestation until delivery. A subset of daily specimens for herpes simplex virus culture and DNA polymerase chain reaction was self-collected. Analyses used chi(2), Fisher exact, and Mann-Whitney U tests. RESULTS: Lesions occurred at delivery among 11 of 78 women (14%) who received placebo and 4 of 84 women (5%) who received acyclovir (P =.08). Herpes simplex virus culture and polymerase chain reaction positivity near delivery occurred in 7% and 34% women in the placebo group and 0 and 2% in the acyclovir group (P =.03 and <.01, respectively). Cesarean delivery for herpes simplex virus occurred in 8 of the women (10%) in the placebo group and in 3 of the women (4%) in the acyclovir group (P =.17). Despite reductions in herpes simplex virus detection, 6% of the women who received acyclovir had herpes simplex virus detected by polymerase chain reaction on >20% of days. Neonatal outcomes were similar between groups. CONCLUSION: Acyclovir significantly reduced, but did not eliminate, herpes simplex virus lesions and detection in late pregnancy.