Jessica Cantu

Tocolytic Therapy for Acute Preterm Labor

The pathophysiology leading to preterm labor is not well understood and often multifactorial; initiating factors include intrauterine infection, inflammation, ischemia, overdistension, and hemorrhage. Given these different potential causes, directing therapy for preterm labor has been difficult and suboptimal. To date, no single drug has been identified as successful in treating all of the underlying mechanisms leading to preterm labor. In addition, the methodology of many of the tocolytic studies is limited by lack of sufficient patient numbers, lack of comparison with a placebo, and inconsistent use of glucocorticoids. The limitations in these individual studies make it difficult to evaluate the efficacy of a single tocolytic by meta-analysis. Despite these limitations, the goals for tocolysis for preterm labor are clear: To complete a course of glucocorticoids and secure the appropriate level of neonatal care for the fetus in the event of preterm delivery. The literature demonstrates that many tocolytic agents inhibit uterine contractility. The decision as to which tocolytic agent should be used as first-line therapy for a patient is based on multiple factors, including gestational age, the patient’s medical history, common and severe side effects, and a patient’s response to therapy. In a patient at less than 32 weeks gestation, indomethacin may be a reasonable first choice based on its efficacy, ease of administration, and minimal side effects. Concurrent administration of magnesium for neuroprotection may be given. At 32 to 34 weeks, nifedipine may be a reasonable first choice because it does not carry the fetal risks of indomethacin at these later gestational ages, is easy to administer, and has limited side effects relative to beta-mimetics. In an effort to review a commonly faced obstetrical complication, this article has provided a summary of the most commonly used tocolytics, their mechanisms of action, side effects, and clinical data regarding their efficacy.

Selective uptake of influenza vaccine and pregnancy outcomes

Abstract Objective: To describe the characteristics of pregnant women who accept the influenza vaccine and evaluate the relationship between vaccination and adverse pregnancy outcomes. Methods: Retrospective cohort study of women receiving prenatal care during the 2009–2011 influenza seasons. Vaccination status was ascertained through our perinatal record system and clinic vaccination logs. Pregnancy outcomes included a primary composite of miscarriage, fetal demise, preterm birth (PTB) <37 weeks and neonatal demise. Stratification and logistic regression were used to adjust for potential confounders. Results: Of 3104 eligible pregnant women, 1094 (35%) received the influenza vaccine. Women vaccinated were more likely to be older, obese, primiparae, and have medical complications or a prior PTB. In univariable analyses, flu vaccination was associated with increased adverse composite outcome and PTB. After multivariable adjustments, vaccination was no longer associated with adverse outcomes in women with medical complications but remained associated with adverse outcomes among those without known co-morbidity. Conclusions: Vaccination was associated with an increased adverse composite outcome in pregnant women without identified co-morbidity but not those with co-morbidities. This association is likely due to selection bias, which should be considered in planning of observational studies of the impact of vaccination on pregnancy outcomes.

Management of influenza in pregnancy.

Influenza is a common viral infection during pregnancy associated with increased adverse maternal and perinatal outcomes. Pregnant women represent a unique population with increased risk for influenza morbidity and mortality. Annual immunization is an effective strategy for prevention of influenza. Despite the universal recommendations for influenza vaccination during pregnancy, 50% or less of pregnant U.S. women on average receive the seasonal vaccine annually. Prompt recognition and treatment of infection or postexposure prophylaxis with recommended antiviral medications may prevent complications in both mother and fetus. We review the epidemiology and management of influenza infection in pregnancy.

Laboratory abnormalities in pregnancy-associated hypertension: frequency and association with pregnancy outcomes

OBJECTIVE: To estimate the frequency of abnormal laboratory test results in pregnancy-associated hypertension and the relationship with pregnancy outcomes. METHODS: This was a secondary analysis of a multicenter trial of vitamin C and E for prevention of pregnancy-associated hypertension in low-risk nulliparous women. Laboratory abnormalities included: platelets less than 100,000/mm3, aspartate aminotransferase 100 units/L or greater, creatinine 1.5 mg/dL or greater, lactate dehydrogenase 600 units/L or greater, total bilirubin 1.2 mg/dL or greater, or evidence of hemolysis on peripheral smear. Mild pregnancy-associated hypertension was defined as blood pressure 140–159/90–109 mm Hg. Severe pregnancy-associated hypertension was defined as persistent blood pressure 160/110 mm Hg or greater, acute antihypertensive treatment, or any blood pressure elevation associated with clinical signs of end-organ dysfunction (one or more of headache, epigastric pain, blurred vision, pulmonary edema, eclampsia, or oliguria). Pregnancy outcomes were compared across four groups: I, mild hypertension alone; II, mild hypertension+abnormal laboratory values; III, severe pregnancy-associated hypertension alone; and IV, severe pregnancy-associated hypertension+abnormal laboratory values. RESULTS: Of 9,969 women, 2,752 (27.9%) developed pregnancy-associated hypertension and of these, laboratory abnormalities occurred in 7.3%. Laboratory abnormalities increased with severity of hypertension: mild hypertension alone (4.9%), severe hypertension alone (8.9%), and mild or severe hypertension with clinical signs of end-organ dysfunction (12.2%) (P for trend<.001). Compared with women with mild hypertension alone, the adjusted odds for the perinatal composite (2-fold to 4.8-fold in Category III–IV), preterm birth (2.1-fold to 7.8-fold in Category II–IV), and other adverse perinatal outcomes increase with disease severity, particularly with laboratory abnormalities and severe clinical signs. CONCLUSION: The frequency of abnormal laboratory values in women with pregnancy-associated hypertension increases with disease severity. Adverse perinatal outcomes increase in the presence of abnormal laboratory values, particularly in those with clinical signs, likely atttributable in part to the decision to deliver early. LEVEL OF EVIDENCE: II

Obesity and Neonatal Cord Blood Gas Results at Cesarean: Effect of Intraoperative Blood Pressure

Objective Our aims were to evaluate whether there is an inverse association between body mass index (BMI) and umbilical artery pH and to investigate the contribution of intraoperative hypotension on the umbilical artery pH. Study Design We conducted a retrospective cohort study of all women with a nonanomalous singleton at 37 to 41 weeks who underwent a scheduled cesarean delivery under spinal anesthesia at our facility from January 2006 to March 2012. The primary outcome was the proportion of patients in each BMI category with arterial cord pH < 7.10. Intraoperative blood pressure data were compared across BMI categories. Results In total, 717 mother‐infant pairs met enrollment criteria. Mean arterial pH was significantly lower in women with elevated BMI (p = 0.014), notably with BMI ≥ 40 kg/m2. Baseline blood pressure increased linearly with increasing BMI (p < 0.001), however, so did the maximum drop in all blood pressure parameters (p < 0.001). After adjusting for potential confounders, including blood pressure, there was no longer an association between cord pH and BMI (p = 0.72). Conclusion For women undergoing a scheduled cesarean delivery under spinal anesthesia, umbilical artery pH is lower in women with BMI ≥40 kg/m2. Relative hypotension after spinal anesthesia is more pronounced with increasing BMI and may explain this effect.

Low-Dose Aspirin, Smoking Status, and the Risk of Spontaneous Preterm Birth

OBJECTIVE We evaluated the relationship between aspirin supplementation and perinatal outcomes for potential effect modification by smoking status. STUDY DESIGN A secondary analysis of two multicenter trials for which prophylactic aspirin supplementation was given to either low- or high-risk women for prevention of preeclampsia (PE). We examined the effect of aspirin by smoking status using the Breslow-Day test. Primary outcomes for this analysis were PE and preterm birth (PTB) < 37 weeks. We also examined PTB subtypes, small for gestational age (SGA), and neonatal intensive care unit (NICU) admission. RESULTS The effect of prenatal aspirin on the risk of PE did not differ by smoking status (relative risk [RR] 95% confidence interval [CI] for smokers; RR 95% CI for nonsmokers) in low-risk (Breslow-Day p = 0.32) or high-risk (RR 95% CI for smokers; RR 95% CI for nonsmokers) (Breslow-Day p = 0.58) women. Among women at low risk for PE, the effect of aspirin supplementation on PTB was not different for nonsmokers (RR 1.00 [95% CI 0.8-1.3]) or smokers (RR 0.80 [95% CI 0.4-1.7]), (Breslow-Day p = 0.54). Aspirin was protective for PTB in nonsmokers (RR 0.80 [95% CI 0.7-0.9]), but not in smokers (RR 1.1 [95% CI 0.9-1.4]) in the high-risk group (Breslow-Day p = 0.03). Aspirin was also associated with increased spontaneous and early PTB and NICU admission in smokers and not nonsmokers in the high-risk group only. CONCLUSION Aspirin supplementation was associated with worse outcomes related to preterm birth in smokers in a high-risk but not low-risk cohort.