Do Previous Cesarean Sections Increase the Risk of Antepartum Stillbirth? RUTH FRETTS MD, MPH123; FREDERIK FRØEN MD, PhD234 , BABILL STRAY-PEDERSEN MD, PhD5 Harvard Vanguard Medical Associates1, Brigham and Women’s Hospital2, Harvard Medical School3,, Norwegian Institute of Pubic Health4, University of Oslo5 Introduction Conclusions We found that there was an association between previous cesarean delivery and subsequent antepartum stillbirth, but this relation was greatly influenced by the reasons the original cesarean section was performed. In the setting where the cesarean was planned either for maternal or fetal reasons, the baby was greater than the 10%, and performed after 36 weeks of gestation, there was no associated risk. We found however that there was an association between cesarean delivery and subsequent antepartum stillbirth when the previous pregnancy was complicated by growth restriction (<10%) or the first cesarean was done for emergency reasons. While there may be direct effect of cesarean of the risk of subsequent stillbirth, it may also be that a history of a previous cesarean delivery is merely a marker for increased fetal and maternal pathology. References 1. Martin JA, Hamilton BE, Sutton PD, Ventura SJ, Menacker F, Munson ML, Births: final data for 2002. Natl Vital Stat Rep 2003;52:1-113. 2. Bailit Jl, Love TE, Mercer B. Rising cesarean rates: are patients sicker? Am J Obstet Gynecol 2004;53:1-17. 3. Parish KM, Holt VL, Connell FA, LoGerfo JP, Effects of changes in maternal age, parity and birthweight distribution on primary cesarean section rates. JAMA 1994;271:443-47. 4. Smith GCS Smith Pell JP, Dobbie R. Caesarean section and risk of unexplained stillbirth in subsequent pregnancy. Lancet 2003:362;1779-84. 5. Salihu HM, Sharma PP, Kristensen S, Blot C, Amina PA, Ananth CV, Kirby RS. Risk of stillbirth following a cesarean delivery Back White disparity. Obstet Gynecol 2006;107:383-90. We found that apart from an increased prevalence of BMI>35 stillbirth mothers were similar than women with a healthy outcome. Women with a healthy outcome had a previous cesarean delivery rate of 22.5% while women who had a stillbirth had a previous cesarean delivery of 28.9%. Women with a previous cesarean were more likely to have had a previous child that was less than the 10% in growth. Then this factor was considered the risk associated with a previous cesarean delivery was reduced. Risk Factor OR 95%C1 Crude: Previous CS 1.40 1.07-1.83 Adjusted: Previous CS 1.29 0.99-1.68 First CS was preterm 1.35 0 92-1.99 First CS was <10% 1.80 1.26-2.56 Women with a stillbirth were more likely to have had a cesarean for emergency reasons (15.5%) when compared to control women (10.6%). The rate of a planned cesarean section (for maternal or fetal reasons) was relatively low (3%). We found that if the mother had had a planned cesarean after 36 weeks of gestation and the baby was normally grown (>10%), that there was no risk associated with a previous cesarean OR 0.94 95% CI 0.65-1.60 However if the mother had a previous cesarean in the setting of a previous growth restricted baby or had an emergency cesarean, the history of a previous cesarean was associated with an increased risk of subsequent stillbirth. OR 1.52 95% CI 1.13-2.04) Since women could have more than one cesarean delivery we repeated the analysis using the reason for the LAST cesarean delivery and found the results similar to the analysis of the reason for the FIRST cesarean section. We chose the first since clinically it begins a cascade of event related to labor and delivery. The rates of cesarean delivery have increased significantly over the past decade to reach nearly 30% in the United States1. The reasons for this increase are multifactorial including increasing maternal age, lower parity, increasing pre-pregnancy obesity and the general medical-legal climate in the United States2,3. The risk between previous cesarean and placenta previa and uterine rupture has been previous described, there are relative rare events. Recently there has been an added concern that while a cesarean delivery might benefit the current pregnancy, it is associated with an increased the risk of an unexplained stillbirth in a subsequent pregnancy4,5. The relationship however may be confounded by the underlying reasons for the first cesarean and not be related to the procedure itself. Methods Data Collected: Mode of recruitment Demographic Hopkins symptom check list Previous and subsequent OB history, and reason for Cesarean delivery Social habits, consumptions General health Symptom and signs in pregnancy Causes and Circumstances of stillbirth A We used an interactive web based questionnaire on www.momstudy.com 37 associations participated in recruiting women who had had a stillbirth and stillbirth moms were asked to recruit women who had had a live birth. A total of 37 organizations were asked to recruit stillbirth mothers to participate, a total of 4246 women completed key questions. The questionnaire was anonymous and interactive and password protected.Figure 1. The study was approved by the Regional Committee for Medical Research Ethics of Southern Norway. Data were transferred from the mysolsq 4 database to SPSS 13.0 and all statistics were performed in SPSS 13.0 Inc., Chicago IL, USA. Results The majority of respondents were from the United States (73%); others lived in the Australia (10%), United Kingdom (9%), Canada (5%), Ireland (1%), New Zealand (1%), one 1% from developing nations. Controls Stillborn White 93% 92% Education<12 yr 23.4% 24.8% Married 88.5% 87.2% BMI>35 7.3% 14.4% p<0.001 DM 6.2% 6.1% PIH/SEVERE 2.5% 3.8% PIH/MILD 9.3% 10.5% Target: Organizations and web sites offering free information or support for families affected by stillbirth From 2699 stillbirth moms (2259 gave complete prior OB history 84% completion rate ) Exclusions:no previous delivery and multiple gestations Cases: 886 12 web search engines and directories Searched both from USA and Norway: “stillbirth”, “fetal death”, “pregnancy loss”, “fetal loss” English, all inflections of terms, updated last 3 months 100 first hits from each search: 749 web pages 1504 live born controls (1361 gave complete prior OB history completion rate 90.5% Exclusions:multiple gestations, no previous delivery and baby that was not healthy at birth) “Healthy Controls”: 444 Exclusions Scientific journals, dictionaries etc. Professional or governmental use only etc. 104 organizations and web sites 100 invited, 4 closed before recruitment B Volunteers 37 recruiting organizations Standardized recommended recruitment materials Baseline Figure 1 and Flow chart for subject recruitment