194: The impact of maternal weight upon the effectiveness of 17-hydroxyprogesterone in preventing preterm birth among twin gestations

betamethasone administration Elizabeth Langen, Jessica Lewis, Joyce Sung, Mark Taslimi, James Byrne, Yasser El-Sayed Stanford University School of Medicine/Lucile Salter Packard Children’s Hospital, Obstetrics & Gynecology, Division of Maternal-Fetal Medicine, Stanford, CA, Stanford University School of Medicine/Lucile Salter Packard Children’s Hospital, Stanford Univeristy School of Medicine, Stanford, CA, Santa Clara Valley Medical Center, Obstetrics & Gynecology, Division of Maternal-Fetal Medicine, San Jose, CA OBJECTIVE: To describe the pattern of maternal glucose response to betamethasone administration using a continuous glucose monitoring system. STUDY DESIGN: A prospective observational trial was conducted among women receiving clinically indicated betamethasone between 24 and 34 weeks of pregnancy. Patients received two doses of 12 mg of betamethasone intramuscularly 24 hours apart. At the time of initial betamethasone administration, a Dexcom continuous glucose monitoring system was inserted which monitored tissue glucose levels every five minutes. Glucose levels were monitored for 7 days or until hospital discharge, whichever came first. We recorded the percentage of time women spent above three glucose thresholds: 110, 144, and 180 mg/dL. These thresholds were chosen as they have been associated with neonatal hypoglycemia in women in labor. Additionally, a comparison was made to a cohort of non-diabetic women of similar gestational ages who did not receive betamethasone. RESULTS: Seventeen women were enrolled at the time of betamethasone administration and data were available for 15 patients. There were 11 non-diabetic and 4 diabetic women. Five additional nondiabetic women who did not receive betamethasone served as controls. The average gestational age at enrollment was 29 2/7wk (range 25 1/7-34wk). Both diabetic and non-diabetic women had the highest recorded blood glucose readings between 2448 hours after the first injection of betamethasone. In that period, non-diabetic women spent 73%, 40%, and 17% of the time with blood glucose levels above the 110, 144, and 180 mg/dL thresholds, respectively. During a 24 hour monitoring period, non-diabetic women not receiving betamethasone spent 27%, 9%, and 0.2% above the same thresholds. At each glucose threshold, the difference between non-diabetics who did and did not receive betamethasone was statistically significant (P 0.003, P 0.03, P 0.01 respectively). CONCLUSION: Diabetic women receiving bethamethasone manifest significant hyperglycemia after betamethasone administration. This may need to be taken into account if delivery is imminent. 194 The impact of maternal weight upon the effectiveness of 17-hydroxyprogesterone in preventing preterm birth among twin gestations Erica Heitmann, George Lu, C. Andrew Combs, Thomas J. Garite, Kimberly Maurel, For the Obstetrix Collaborative Research Network University of Missouri, Kansas City, Department of Obstetrics and Gynecology, Kansas City, MO, Obstetrix Medical Group of Kansas and Missouri, Center for Research, Education, & Quality, Kansas City, MO, Obstetrix Medical Group, Center for Research, Education, & Quality, Sunrise, FL, Obstetrix Medical Group twins trial OBJECTIVE: To evaluate the impact of maternal weight on the efficacy of 17-hydroxyprogesterone caproate (17P) for the prevention of preterm birth (PTB) in twin gestations and reduction of composite neonatal morbidity (CNM). We hypothesized that 17P would be more effective in non-obese women because a prior pharmacokinetic study had demonstrated a significant impact of maternal BMI upon 17P serum concentrations. STUDY DESIGN: A secondary analysis was performed on data from the Obstetrix trial of 17P in twins. 234 patients had recorded maternal weight and were included in the analysis. Pre-pregnancy maternal weight was calculated as quartiles (Q): Q1 97-133 pounds; Q2 133150 pounds; Q3 150-176 pounds; and Q4 176-332 pounds. PTB was defined as 2 categories: 34 weeks and 34.0-36.9 weeks. Rates of PTB and CNM were calculated in each quartile for both the 17 P and placebo groups using the Fishers exact test. RESULTS: The rate of PTB .05). The rates of PTB .05). When BMI was used, the rate of PTB .05). When BMI was examined for PTB .05). Survival analysis showed that 17P did not significantly prolong pregnancy compared to placebo in any tercile of weight or BMI. CONCLUSION: 17P is not more effective in preventing PTB in lower weight categories, regardless of the definition used. This suggests that maternal weight does not explain the failure of 17P to prolong pregnancy in twins.