Single-test syphilis serology: A case of not seeing the forest for the trees.

INTRODUCTION: There have been few empirical studies for diagnostic test accuracy of syphilis using a sequence of rapid tests in populations with low prevalence of syphilis such as pregnant women. This analysis describes syphilis test positivity frequency among pregnant women at an antenatal clinic in Zambia using a reverse-sequence testing algorithm for antenatal syphilis screening. METHODS: Between August 2019 and May 2023, we recruited 1510 pregnant women from a peri-urban hospital in Lusaka, Zambia. HIV positive and HIV negative women were enrolled in a 1:1 ratio. Blood collected at recruitment from the pregnant mothers was tested on-site for syphilis using a rapid treponemal test. Samples that tested positive were further tested at a different laboratory, with rapid plasma reagin using archived plasma. RESULTS: Of the total 1,421 sera samples which were screened with a rapid treponemal test, 127 (8.9%) were positive and 1,294 (91.1%) were negative. Sufficient additional samples were available to perform RPR testing on 114 of the 127 (89.8%) RDT positive specimens. Thirty-one (27.2%) of these 114 were reactive by RPR and 83 (72.8%) were negative, resulting in a syphilis overtreatment rate of 3 fold (i.e, 84/114). Insufficient sample or test kit availability prevented any testing for the remaining 89 (5.9%) participants. CONCLUSION: Use of only treponemal tests in low prevalence populations, like pregnant women, subjects individuals with non-active syphilis to the costs and possible risks of overtreatment. The use of the dual treponemal and non-treponemal tests would minimize this risk at some additional cost.

Perioperative Antibiotics and Other Factors Associated with Postcesarean Infections: A Case-Control Study.

OBJECTIVE: Our objective was to determine modifiable risk factors associated with surgical site infection (SSI) and postpartum endometritis. We hypothesized that inappropriate surgical antibiotic prophylaxis would be a risk factor for both types of infections. STUDY DESIGN: This was a single-center case-control study of SSI and endometritis after cesarean delivery over a 2-year period from 2016 to 2017. Cases were identified by International Classification of Diseases, 10th Revision diagnosis codes, infection control surveillance, and electronic medical records search and were subsequently confirmed by chart review. Three controls were randomly selected for each case from all cesareans ± 48 hours from case delivery. Demographic, pregnancy, and delivery characteristics were abstracted. Separate multivariable logistic regression models were used to assess factors associated with SSI and endometritis. Postpartum outcomes, including length of stay and readmission, were also compared. RESULTS: We identified 141 cases of SSI and endometritis with an overall postpartum infection rate of 4.0% among all cesarean deliveries. In adjusted analysis, factors associated with both SSI and endometritis were intrapartum delivery, classical or other (non-low-transverse) uterine incision, and blood transfusion. Factors associated with SSI only included inadequate antibiotic prophylaxis, public insurance, hypertensive disorder of pregnancy, and nonchlorhexidine abdominal preparation; factors only associated with endometritis included ß-lactam allergy, anticoagulation therapy, and chorioamnionitis. Among cases, 34% of those with SSI and 25% of those with endometritis did not receive adequate antibiotic prophylaxis, compared with 12.9 and 13.5% in control groups, respectively. Failure to receive appropriate antibiotic prophylaxis was associated with an increased risk of SSI (adjusted odds ratio [aOR]: 4.4, 95% confidence interval [CI]: 1.3-15.6) but not endometritis (aOR 0.9, 95% CI 0.4-2.0). CONCLUSION: Inadequate surgical antibiotic prophylaxis was associated with an increased risk of SSI but not postpartum endometritis, highlighting the different mechanisms of these infections and the importance of prioritizing adequate surgical prophylaxis. Additional potentially modifiable factors which emerged included blood transfusion and chlorhexidine skin preparation. KEY POINTS: · Inadequate antibiotic prophylaxis is associated with a four-fold risk in surgical site infections.. · The most common cause for failure to achieve adequate surgical prophylaxis was inappropriate timing of antibiotics at or after skin incision.. · Blood transfusions are strongly associated (>10-fold risk) with both SSI and endometritis..

Vancomycin during delivery hospitalizations for women with group B streptococcus.

OBJECTIVE: Vancomycin use for intrapartum GBS prophylaxis is not well characterized. The objective of this study was to describe trends in the use of vancomycin among women undergoing vaginal delivery with group B Streptococcus (GBS) colonization. METHODS: An administrative inpatient database that includes medications was analyzed to evaluate antibiotic use in women undergoing vaginal delivery hospitalizations complicated by GBS colonization from January 2006 to March 2015. Patients with other obstetric or infectious indications for antibiotics were excluded. Frequency of use of individual antibiotic agents was determined. The Cochran-Armitage test was used to assess temporal trends. An adjusted log-linear regression model accounting for demographic and hospital factors with vancomycin receipt as the outcome was performed with adjusted risk ratios (aRR) and 95% confidence intervals (CI) as the measure of effect. Hospital level variation in administration of vancomycin was also evaluated. RESULTS: 469,717 deliveries met inclusion criteria and were included in this analysis. Use of vancomycin increased from 0.8% of patients in 2006 to 3.8% of patients in the first quarter of 2015. Comparing 2015 to 2006 both the unadjusted (relative risk 4.89 95% CI 4.26-5.60) and adjusted (aRR 4.52 95% 3.94-5.19) models demonstrated significantly increased likelihood of vancomycin administration. In evaluating hospital level vancomycin use, variation was noted with 8.0% of centers administering vancomycin to ≥6.0% of patients. CONCLUSIONS: Vancomycin is becoming increasingly commonly used for intrapartum GBS prophylaxis. Further research and quality improvements initiatives are indicated to optimize intrapartum GBS antibiotic prophylaxis.

Persistent Immune Activation in Human Immunodeficiency Virus-Infected Pregnant Women Starting Combination Antiretroviral Therapy After Conception.

This study evaluated the impact of human immunodeficiency virus (HIV) and combination antiretroviral therapy (cART) on immune activation during pregnancy in a Zambian cohort of HIV-exposed but uninfected children followed up from birth. Activated CD8+ T cells (CD38+ and HLA-DR+) were compared among HIV-uninfected (n = 95), cART experienced HIV-infected (n = 111), and cART-naive HIV-infected (n = 21) pregnant women. Immune activation was highest among HIV-infected/cART-naive women but decreased during pregnancy. Immune activation HIV-infected women who started cART during pregnancy was reduced but not to levels similar to those in HIV-uninfected women. The effects of elevated maternal immune activation in pregnancy on subsequent infant health and immunity remain to be determined.

Multifetal Gestations and Associated Perinatal Risks.

Along with the rise of assisted reproductive technology, multifetal gestations increased dramatically. Twin pregnancies account for 97% of multifetal pregnancies and 3% of all births in the United States. Twins and higher-order multiples carry increased risks of obstetric, perinatal, and maternal complications; these risks increase with increasing fetal number. Neonatal morbidity and mortality in multifetal gestations is driven primarily by prematurity. Both spontaneous and indicated preterm births are increased in multifetal gestations, and only a limited number of strategies are available to mitigate this risk. No single intervention has been shown to decrease the rate of spontaneous preterm birth in most twin pregnancies. Low-dose aspirin prophylaxis is recommended in all multifetal pregnancies to reduce the risk of preeclampsia and its associated complications. Antenatal management of multifetal gestations depends on chorionicity, which should be established using ultrasonography in the first trimester. Unlike dichorionic twin gestations, monochorionic pregnancies experience unique complications because of their shared vascular connections, and therefore, need frequent ultrasound surveillance. Even uncomplicated twin gestations have higher rates of unanticipated stillbirth compared with singletons. Delivery of twin pregnancies is generally indicated in the late preterm to early term period depending on chorionicity and other clinical factors. For most diamniotic twin pregnancies with a cephalic presenting fetus, vaginal delivery after 32 weeks' gestation is a safe and reasonable option with high rates of success and no increased risk of perinatal morbidity.

A randomized trial of the bactericidal effects of chlorhexidine vs povidone-iodine vaginal preparation.

BACKGROUND: Precesarean vaginal preparation significantly reduces postpartum infections. Although povidone-iodine is the most commonly used vaginal antiseptic, evidence suggests that chlorhexidine gluconate may be more effective. OBJECTIVE: We aimed to compare the bactericidal effect of chlorhexidine gluconate and povidone-iodine on vaginal bacterial colony counts in pregnancy. MATERIALS AND METHODS: We conducted a prospective randomized controlled trial of vaginal preparation with 0.5% chlorhexidine gluconate vs 10% povidone-iodine vs saline in women undergoing cesarean delivery at ≥34 weeks' gestation. Women in labor or those with ruptured membranes, chorioamnionitis, abnormal placentation, or allergy to study agents were excluded. Vaginal specimens were collected aseptically in the operating room immediately before and 5-10 minutes after vaginal cleansing with 3 sterile sponge sticks. Our primary outcome was postintervention aerobic and anaerobic bacterial colony counts, assessed by blinded investigators. Two-way analysis of variance with simple-effects analysis and Tukey post hoc test were used for multiple group comparisons. Secondary outcomes included baseline colony counts, change in colony counts, adverse events, and maternal infections. RESULTS: A total of 29 women consented and underwent vaginal preparation with chlorhexidine gluconate (n=10), povidone-iodine (n=9), or saline (n=10). Groups were similar with respect to maternal age, body mass index, race, ethnicity, parity, group B streptococcus status, and gestational age. There were no differences in baseline colony counts. Vaginal preparation with povidone-iodine resulted in lower aerobic and anaerobic colony counts compared with chlorhexidine gluconate and saline (P≤.01 and P≤.0001, respectively). Povidone-iodine eliminated more than 99.9% of bacteria, whereas chlorhexidine gluconate and saline eliminated more than 99% and 95% of bacteria, respectively. Although all agents decreased aerobic and anaerobic bacterial counts, 0.5% chlorhexidine gluconate was no more effective than saline in reducing anaerobic bacteria. There were no reported adverse effects or postpartum infections. CONCLUSION: Compared with 0.5% chlorhexidine gluconate, 10% povidone-iodine was more effective in reducing vaginal bacterial colony counts before cesarean delivery.

Oral Opioid Use during Vaginal Delivery Hospitalizations.

OBJECTIVE: This study aimed to determine the receipt of short-acting opioid medications during vaginal delivery hospitalizations. STUDY DESIGN: The Perspective database was analyzed to evaluate patterns of short-acting oral opioid use during vaginal delivery hospitalizations from January 2006 to March 2015. Unadjusted and adjusted models evaluating the role of demographic and hospital factors were created evaluating use of opioids. Hospital-level rates of opioid use were evaluated. Opioid receipt among women with opioid abuse or dependence was evaluated based on overall hospital rates of opioid use. RESULTS: Of 3,785,396 vaginal delivery hospitalizations from 2006 to 2015, 1,720,899 (45.5%) women received an oral opioid for pain relief. Opioid use varied significantly among the 458 hospitals included in the analysis, with one-third of hospitals providing opioids to <38% of patients, one-third to 38 to <59% of patients, and one-third to ≥59% of patients. When hospitals were stratified by overall opioid administration rates, women with opioid abuse or dependence were less likely to be given opioids in hospitals with low overall opioid rates. DISCUSSION: The use of opioid pain medications during vaginal delivery hospitalizations varied significantly among hospitals, suggesting that standardization of pain management practices could reduce opioid use.

Clindamycin, Gentamicin, and Risk of Clostridium difficile Infection and Acute Kidney Injury During Delivery Hospitalizations.

OBJECTIVE: To describe risk of Clostridium difficile infection associated with clindamycin and acute kidney injury associated with gentamicin during delivery hospitalizations. METHODS: Women admitted for delivery from January 2006 to March 2015 were analyzed using an inpatient administrative database. Primary outcomes were C difficile infection and acute kidney injury. C difficile infection was compared between women receiving clindamycin (with or without other antibiotics) and women receiving antibiotics other than clindamycin. Acute kidney injury was compared between women receiving gentamicin (with or without other antibiotics), women receiving antibiotics other than gentamicin, and women receiving no antibiotics. Unadjusted and adjusted log linear models analyzing the role of patient demographics, mode of delivery, and hospital-level characteristics were created evaluating risk of C difficile infection and acute kidney injury with risk ratios (RRs) and adjusted risk ratios with 99% CIs as measures of association. A sensitivity analysis for gentamicin and acute kidney injury was performed restricted to women with preeclampsia. RESULTS: Of 5,657,523 women admitted for delivery hospitalization, 266,402 (4.7%) received clindamycin and 165,726 (2.9%) received gentamicin. C difficile infection was diagnosed in 0.04% of women receiving clindamycin. Compared with women receiving other antibiotics, clindamycin was associated with a nearly threefold increased risk of C difficile infection (RR 2.93, 99% CI 2.21-3.90). Acute kidney injury was diagnosed in 0.24% of women receiving gentamicin. Gentamicin was associated with a threefold increased risk of acute kidney injury (RR 3.01, 99% CI 2.62-3.45) compared with women receiving other antibiotics, whereas receipt of no antibiotics was associated with significantly lower risk (RR 0.18, 99% CI 0.15-0.20). In adjusted analyses, these associations retained significance. Significantly increased risk of acute kidney injury was noted for women with preeclampsia receiving gentamicin (RR 2.04, 99% CI 1.64-2.53). CONCLUSION: Receipt of clindamycin was associated with significantly increased likelihood for C difficile infection and receipt of gentamicin with significantly increased likelihood of acute kidney injury, although the absolute risk of these complications was low.

Antibiotics for 3rd and 4th Degree Vaginal Lacerations, Uterine Tamponade, and Manual Placental Extraction.

OBJECTIVE: Trends in use of antibiotics during delivery hospitalizations complicated by (1) 3rd/4th degree vaginal lacerations, (2) manual placenta extraction, and (3) uterine tamponade are not well characterized. The objective of this study was to analyze trends in antibiotic use during vaginal delivery hospitalizations complicated by these three clinical scenarios. STUDY DESIGN: An administrative inpatient database was used to perform a serial cross-sectional analysis of antibiotic administration during delivery hospitalizations in the United States from January 2006 to March 2015. The primary outcome was receipt of antibiotics during vaginal delivery hospitalizations complicated by (1) 3rd and 4th degree vaginal lacerations, (2) manual placenta extraction, and (3) uterine tamponade. Patients with other indications for antibiotics were excluded. The Cochran-Armitage test was used to assess trends. Adjusted log linear regression analyses including demographic, hospital, and obstetric factors were performed to analyze factors associated with antibiotic receipt for each of these three clinical scenarios in both primary and sensitivity analyses. RESULTS: From 2006 to 2015 the rate of antibiotic administration during delivery hospitalizations decreased from 43.1% in 2006 to 25.5% for 3rd and 4th degree lacerations and from 59.6% to 49.2% for manual extraction (p < 0.01). Administration of antibiotics in the setting of uterine tamponade decreased from 48.6% in 2006 to 27.6% in 2009 before rising to 62.5% in the first quarter of 2015. In adjusted analyses, comparing the first quarter of 2015 to 2006 adjusted risk ratios for antibiotic administration were 0.61 (95% confidence interval [CI] 0.56-0.66) for 3rd and 4th degree vaginal lacerations, 0.76 (95% CI 0.53-1.09) for manual placental extraction, and 0.83 (95% CI 0.76-0.92) for uterine tamponade. CONCLUSION: Antibiotics are not used consistently during vaginal deliveries complicated by 3rd/4th degree lacerations, manual placenta extraction, and uterine tamponade. These findings support that a significant opportunity exists for comparative effectiveness research to assist in characterizing best practices.

Antibiotic Use Without Indication During Delivery Hospitalizations in the United States.

OBJECTIVE: To analyze trends in unindicated antibiotic use during vaginal delivery hospitalization. METHODS: This study used an administrative database to analyze antibiotic use during delivery hospitalizations from January 2006 to March 2015. Women were classified by mode of delivery and whether they had an evidence-based indication for antibiotics. Indications for antibiotics included preterm prelabor rupture of membranes (PROM), cesarean delivery, group B streptococcus (GBS) colonization, chorioamnionitis, endometritis, urinary tract infections, and other infections. The Cochran-Armitage test was used to assess trends of antibiotic administration. Unadjusted and adjusted analyses for antibiotic receipt including demographic, hospital, and obstetric and medical factors were performed with unadjusted and adjusted risk ratios (RRs) with 95% CIs as measures of association. RESULTS: A total of 5,536,756 delivery hospitalizations, including 2,872,286 vaginal deliveries without an indication for antibiotics, were analyzed. The most common indication for antibiotics was cesarean delivery (33.6% of the entire cohort), followed by GBS colonization (15.8%), chorioamnionitis (1.7%), preterm PROM (1.6%), endometritis (1.2%), urinary tract infections (0.6%), and other infections (total less than 0.5%). The proportion of women receiving unindicated antibiotics decreased 44.4%, from 38.1% in 2006 to 21.2% in 2015. Adjusted risk for receipt of unindicated antibiotics was lower in 2015 vs 2006 (adjusted RR 0.56, 95% CI 0.55-0.57). CONCLUSION: Use of antibiotics during vaginal delivery hospitalizations without an indication for antibiotic use declined significantly based on an analysis of a large administrative data set.

Outcomes research on obstetric venous thromboembolism.

Outcomes research on obstetric venous thromboembolism (VTE) involves a number of major challenges. While obstetric VTE, including deep vein thrombosis and pulmonary embolism, is relatively common on a population basis, diagnoses during pregnancy are relatively rare in comparison to high-risk scenarios such as orthopedic surgery. This review characterizes outcomes research on obstetric VTE with a focus on strengths, limitations, and appropriate inferences from existing research. It is divided into four sections. First, evidence regarding validity of diagnosis codes for VTE in administrative data is reviewed. Second, limitations of both clinical research and administrative-data study models are analyzed. Third, examples of high-quality obstetric VTE research from the literature and opportunities for improved research in the future are reviewed. Fourth, future directions for research are explored.

Incorporating Precesarean Vaginal Preparation Into Standard of Care for Obstetrics.

Postoperative infections remain a serious concern after cesarean delivery, the most common major surgical procedure in the United States. Multiple strategies have been proposed to combat this problem, including the addition of azithromycin to the standard preoperative antibiotic prophylaxis. However, as obstetricians, we have failed to uniformly adopt precesarean vaginal preparation despite convincing evidence from randomized controlled trials that this technique reduces postoperative rates of endometritis by more than 50%. This reduction is similar to that seen with the addition of azithromycin. Vaginal preparation with povidone-iodine solution may target the same genital pathogens as azithromycin, which are commonly implicated in endometritis, a polymicrobial infection that may be under-addressed by our current antiseptic techniques. A recent review of maternal-fetal medicine fellows' practices at the time of cesarean delivery and recent publications on precesarean vaginal cleansing suggest that this practice has not yet gained hold in the United States.

Malpresentation in low- and middle-income countries: Associations with perinatal and maternal outcomes in the Global Network.

INTRODUCTION: Uncertainty exists regarding the impact of malpresentation on pregnancy outcomes and the optimal mode of delivery in low- and middle-income countries. We sought to compare outcomes between cephalic and non-cephalic pregnancies. MATERIAL AND METHODS: Using the NICHD Global Network's prospective, population-based registry of pregnancy outcomes from 2010 to 2016, we studied outcomes in 436 112 singleton pregnancies. Robust Poisson regressions were used to estimate the risk of adverse outcomes associated with malpresentation. We examined rates of cesarean delivery for malpresentation and compared outcomes between cesarean and vaginal delivery by region. RESULTS: Across all regions, stillbirth and neonatal mortality rates were higher among deliveries with malpresentation. In adjusted analysis, malpresentation was significantly associated with stillbirth (adjusted relative risk [aRR] 4.0, 95% confidence interval [CI] 3.7-4.5) and neonatal mortality (aRR 2.3, 95% CI 2.1-2.6). Women with deliveries complicated by malpresentation had higher rates of morbidity and mortality. Rates of cesarean delivery for malpresentation ranged from 27% to 87% among regions. Compared with cesarean delivery, vaginal delivery for malpresentation was associated with increased maternal risk, especially postpartum hemorrhage (aRR 5.0, 95% CI; 3.6-7.1). CONCLUSIONS: In a cohort of deliveries in low- and middle-income countries, malpresentation was associated with increased perinatal and maternal risk. Further research is needed to determine the best management of these pregnancies.

Trends and Outcomes Associated With Using Long-Acting Opioids During Delivery Hospitalizations.

OBJECTIVE: To assess trends in use of long-acting opioids during delivery hospitalizations. METHODS: The Perspective database, an administrative inpatient database that includes medication receipt, was analyzed to evaluate patterns of long-acting opioid use during delivery hospitalizations from January 2006 through March 2015. Medications evaluated included methadone, formulations including buprenorphine and extended-release formulations of oxycodone, morphine, fentanyl, and other opioids. Temporal trends in use of these medications were determined. Unadjusted and adjusted models evaluating the role of demographic and hospital factors were created evaluating both use of these medications and risk for severe morbidity. Risk for severe morbidity was determined based on Centers for Disease Control and Prevention criteria. RESULTS: Our analysis included 2,994,630 delivery hospitalizations meeting study criteria. Over the entire study period, use of long-acting opioids increased significantly from 457 to 844 per 100,000 deliveries. Although buprenorphine and methadone use increased, use of other long-acting opioids decreased. In 2006, methadone and buprenorphine accounted for less than one third of all long-acting opioids used during delivery hospitalizations. By 2015, buprenorphine and methadone represented 73.5% of long-acting opioids used. In adjusted and unadjusted models, risk for severe morbidity was significantly lower with buprenorphine or methadone compared with other long-acting opioids. Restricting the cohort to only women with drug abuse or dependence, risk for severe morbidity was lower with methadone and buprenorphine than without any long-acting opioids. CONCLUSION: Increased use of methadone and buprenorphine in this study supports the feasibility of use of these medications during pregnancy and uptake of clinical recommendations for women with opioid use disorder. Use of methadone and buprenorphine is associated with decreased maternal morbidity, although causation cannot be presumed from this study model.

Number of cervical examinations and risk of intrapartum maternal fever.

OBJECTIVE: To estimate the association between number of cervical examinations and risk of maternal fever during term labor and delivery. METHODS: Within a 4-year retrospective cohort study of all consecutive term (37 weeks of gestation or more) singleton deliveries reaching the second stage of labor, we identified women who developed an intrapartum fever and compared them with women who remained afebrile through 6 hours postpartum. Primary exposure was number of digital cervical examinations. Extensive data were collected from the medical record, including obstetric and medical history, cervical examinations and timing, admitting diagnoses, and outcomes. Time-to-event analyses were used to account for length of labor. Cox proportional hazard models were developed adjusting for potentially confounding factors. RESULTS: Of 2,395 women who were afebrile at admission, 174 (7.2%) developed an intrapartum fever. Women were examined one to 14 times. There was no significant association between increasing number of examinations and risk of fever. Even for the 505 women who had more than seven examinations during labor, there was no statistically significant increased risk of fever (hazard ratio 0.9, 95% confidence interval 0.4-2.0) compared with those with one to three examinations. Subanalyses by labor type and examinations after rupture of membranes also showed no significant association between number of cervical examinations and risk of intrapartum fever. CONCLUSION: During term labor management, maternal fever risk is not significantly increased by the number of cervical examinations. LEVEL OF EVIDENCE: II.

Effect of magnesium sulfate on fetal heart rate patterns in the second stage of labor.

OBJECTIVE: To estimate the effect of maternal exposure to magnesium sulfate on fetal heart rate characteristics during active labor. METHODS: Within a 4-year retrospective cohort study of consecutive term deliveries reaching the second stage of labor, we compared women exposed to magnesium for severe preeclampsia to all women not exposed. Primary outcome was the electronic fetal monitoring tracing in the 30 minutes preceding delivery. Secondary outcomes were fetal acidemia and nursery disposition. Attributable risk estimates and multivariable logistic regression were used to estimate the association between magnesium exposure and fetal heart rate characteristics. Unadjusted risk estimates for the association between fetal heart rate characteristics and neonatal outcomes were generated stratified by group. RESULTS: Of 5,387 women, 248 (4.6%) were exposed to magnesium. Magnesium exposure was associated with lower fetal heart rate baseline (136.9 ± 12.3 beats per minute compared with 139.0 ± 13.5 beats per minute; P=.02), increased risk of baseline less than 120 beats per minute (adjusted odds ratio [OR] 1.76, 95% confidence interval [CI] 1.21-2.56), and increased risk of absent or minimal variability (adjusted OR 2.41, 95% CI 1.78-3.27). More than 20% increased frequency of ever absent or minimal variability was attributable to magnesium (attributable risk 0.21, 95% CI 0.15-0.27). There were no significant differences in presence or number of accelerations or decelerations; however, magnesium was associated with fewer prolonged decelerations (adjusted OR 0.64, 95% CI 0.49-0.84). After excluding women with adverse neonatal outcomes, these associations remained. CONCLUSION: Maternal exposure to magnesium is associated with lower fetal heart rate baseline within the accepted normal range, decreased variability, and fewer prolonged decelerations without evidence of adverse effect on neonatal outcome. LEVEL OF EVIDENCE: II.