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797: Fetal gender of the first born and the recurrent risk of spontaneous preterm birth
Poster Session V 797 Fetal gender of the first born and the recurrent risk of spontaneous preterm birth
Esme Kamphuis1, Bouchra Koullali1, Michel Hof2, Christianne de Groot3, Brenda Kazemier1, Ben Willem Mol5, Anita Ravelli4
1 AMC, Gynaecology and Obstetrics, Amsterdam, Netherlands, 2AMC, Department of Clinical Epidemiology, Bioinformatics, and Biostatistics, Amsterdam, Netherlands, 3VU University Medical Center, Department of Obstetrics and Gynaecology, Amsterdam, Netherlands, 4AMC, Department of medical informatics, Amsterdam, Netherlands, 5The Robinson Institute, School of Paediatrics and Reproductive Health, Adelaide, SA, Australia
OBJECTIVE: Spontaneous preterm birth (sPTB) is a serious obstetric
problem caused by multiple processes. It is known that male fetal gender increases the risk of PTB. This suggests that when women deliver preterm from a female fetus, an underlying maternal factor might be present. To test this hypothesis we studied the effect of fetal sex conditional on sPTB in the 1st pregnancy and the risk of recurrent sPTB in the subsequent pregnancy. STUDY DESIGN: We used the population based longitudinal linked dataset of the national Perinatal Registration with two subsequent singleton pregnancies in the Netherlands (1999-2009). We included women with the 1st and 2nd birth, from 22.0 weeks onwards, while women with iatrogenic delivery <37 weeks (induction or primary caesarean section), antenatal deaths and congenital abnormalities were excluded. Logistic regression analysis was used to estimate the risk of sPTB in the 2nd pregnancy in relation to fetal sex of the 1st pregnancy conditional on sPTB in the 1st pregnancy. We adjusted for maternal age, ethnicity, social economic status, pregnancy after ART, interpregnancy interval and fetal gender and birth weight in the 2nd pregnancy. RESULTS: We studied 343,853 women, of whom 1,727 (0.50%) suffered sPTB <32 weeks in the 1st pregnancy (0.41% (692/ 167,630) for female fetuses; 0.59% (1,035/176,223) for male fetuses). When the 1st pregnancy had ended <32 weeks and the baby was female, the risk of sPTB < 32 weeks in the 2nd pregnancy was significantly increased compared to when the 1st pregnancy was male ((8.2% vs 5.9%; aOR 4.2 (95% CI 1.5 to 12)). The risk of recurrent sPTB <37 weeks after sPTB <37 weeks in the 1st pregnancy shows similar results ((15.8% vs 15.2%; aOR 1.2 (95% CI 1.04 to 1.3)). CONCLUSION: Women who suffer sPTB while being pregnant from a female fetus have an increased risk of repeat sPTB as compared to women who suffer sPTB of a male fetus. This adds to the hypothesis that fetal and maternal factors contribute independently to the risk of initial and recurrent PTB.
ajog.org 798 Population differences influence effectiveness of progesterone in women with threatened preterm labor
Frederik Hermans1, Ariel Karolinski4, Ve´ronique Othenin-Girard3, Ewoud Schuit8, Christina Laterra7, Irene Ho¨sli6, Daniel Ferna´ndez5, Olivier Irion3, Victoria Bertolino4, Ben Mol2, Begon˜a Martinez de Tejada3, 4P Group3
1 Academic Medical Center, Department of Obstetrics and Gynaecology, Amsterdam, Netherlands, 2University of Adelaide, The Robinson Institute School of Paediatrics and Reproductive Health, Adelaide, SA, Australia, 3 Geneva University Hospitals and University of Geneva Faculty of Medicine, Department of Obstetrics and Gynaecology, Geneva, Switzerland, 4Hospital GA Carlos G Durand, Population Health Research Centre, Buenos Aires, Argentina, 5Hospital Materno Infantil de San Isidro, Department of Obstetrics and Gynaecology, San Isidro, Argentina, 6University Hospital, University Basel, Department of Obstetrics and Gynaecology, Basel, Switzerland, 7Hospital Materno Infantil Ramón Sardá, Department of Obstetrics and Gynaecology, Buenos Aires, Argentina, 8University Medical Center Utrecht, Julius Center for Health Sciences and Primary Care, Utrecht, Netherlands
OBJECTIVE: Threatened preterm labor (tPTL) is a common complication of pregnancy. However, identification of women at high risk for early delivery is difficult and its clinical definition differs between countries, which result in different preterm birth (PTB) rates between tPTL populations in those countries. Our objective was to assess whether there was a difference in risk for PTB after tPTL, and in effectiveness of progesterone between two tPTL populations. STUDY DESIGN: We performed a secondary analysis of an RCT conducted in Argentina and Switzerland that studied the association between vaginal progesterone and PTB in women with tPTL between 24 and 34 weeks (4P-trial NCT00536003). We performed Cox proportional hazards analysis to compare time-to-delivery, specifically within 7 and 14 days and before 34 and 37 weeks, between progesterone and placebo. Differences in treatment effects between countries were assessed by adding a treatment-country interaction term, and subsequent stratified analysis within countries. Analysis was adjusted for baseline differences between populations. We censored women with iatrogenic onset of labor at moment of delivery or those reaching 34 or 37 weeks. RESULTS: A total of 379 women were analyzed. Swiss (n¼172) and Argentinian (n¼207) women differed on age, weight, ethnicity, social class, parity and anatomical risk factors, but overall PTB risks were similar. There were significant country-treatment interactions for PTB within 14 days and before 34 and 37 weeks (p-values: 0.037, 0.005 and 0.025). Stratified analysis showed that in Switzerland progesterone use increased the risk for PTB within 14 days, and before 34 and 37 weeks with an adjusted HR of 4.3 (95% CI 1.2 15.8), 15.8 (95% CI 2.1 - 120.3) and 2.7 (95% CI 1.4 - 5.2), respectively. (See table) In Argentina these differences were not found. CONCLUSION: In women with tPTL effects of progesterone vary, even after adjustment of population differences. Population differences should be considered in multicenter trials.
*The odds ratio (OR) expresses the risk of sPTB in the 2nd pregnancy in women who delivered a preterm girl as compared to those who delivered a preterm boy in the 1st pregnancy. {Adjusted for: gender second pregnancy, birth weight, ART, low SES, ethnicity (Non White European), maternal age <25 year, interpregnancy interval (0-25 percentile,50-75 percentile,75-100 percentile) all in second pregnancy.
S386 American Journal of Obstetrics & Gynecology Supplement to JANUARY 2015
Esme Kamphuis1, Bouchra Koullali1, Michel Hof2, Christianne de Groot3, Brenda Kazemier1, Ben Willem Mol5, Anita Ravelli4
1 AMC, Gynaecology and Obstetrics, Amsterdam, Netherlands, 2AMC, Department of Clinical Epidemiology, Bioinformatics, and Biostatistics, Amsterdam, Netherlands, 3VU University Medical Center, Department of Obstetrics and Gynaecology, Amsterdam, Netherlands, 4AMC, Department of medical informatics, Amsterdam, Netherlands, 5The Robinson Institute, School of Paediatrics and Reproductive Health, Adelaide, SA, Australia
OBJECTIVE: Spontaneous preterm birth (sPTB) is a serious obstetric
problem caused by multiple processes. It is known that male fetal gender increases the risk of PTB. This suggests that when women deliver preterm from a female fetus, an underlying maternal factor might be present. To test this hypothesis we studied the effect of fetal sex conditional on sPTB in the 1st pregnancy and the risk of recurrent sPTB in the subsequent pregnancy. STUDY DESIGN: We used the population based longitudinal linked dataset of the national Perinatal Registration with two subsequent singleton pregnancies in the Netherlands (1999-2009). We included women with the 1st and 2nd birth, from 22.0 weeks onwards, while women with iatrogenic delivery <37 weeks (induction or primary caesarean section), antenatal deaths and congenital abnormalities were excluded. Logistic regression analysis was used to estimate the risk of sPTB in the 2nd pregnancy in relation to fetal sex of the 1st pregnancy conditional on sPTB in the 1st pregnancy. We adjusted for maternal age, ethnicity, social economic status, pregnancy after ART, interpregnancy interval and fetal gender and birth weight in the 2nd pregnancy. RESULTS: We studied 343,853 women, of whom 1,727 (0.50%) suffered sPTB <32 weeks in the 1st pregnancy (0.41% (692/ 167,630) for female fetuses; 0.59% (1,035/176,223) for male fetuses). When the 1st pregnancy had ended <32 weeks and the baby was female, the risk of sPTB < 32 weeks in the 2nd pregnancy was significantly increased compared to when the 1st pregnancy was male ((8.2% vs 5.9%; aOR 4.2 (95% CI 1.5 to 12)). The risk of recurrent sPTB <37 weeks after sPTB <37 weeks in the 1st pregnancy shows similar results ((15.8% vs 15.2%; aOR 1.2 (95% CI 1.04 to 1.3)). CONCLUSION: Women who suffer sPTB while being pregnant from a female fetus have an increased risk of repeat sPTB as compared to women who suffer sPTB of a male fetus. This adds to the hypothesis that fetal and maternal factors contribute independently to the risk of initial and recurrent PTB.
ajog.org 798 Population differences influence effectiveness of progesterone in women with threatened preterm labor
Frederik Hermans1, Ariel Karolinski4, Ve´ronique Othenin-Girard3, Ewoud Schuit8, Christina Laterra7, Irene Ho¨sli6, Daniel Ferna´ndez5, Olivier Irion3, Victoria Bertolino4, Ben Mol2, Begon˜a Martinez de Tejada3, 4P Group3
1 Academic Medical Center, Department of Obstetrics and Gynaecology, Amsterdam, Netherlands, 2University of Adelaide, The Robinson Institute School of Paediatrics and Reproductive Health, Adelaide, SA, Australia, 3 Geneva University Hospitals and University of Geneva Faculty of Medicine, Department of Obstetrics and Gynaecology, Geneva, Switzerland, 4Hospital GA Carlos G Durand, Population Health Research Centre, Buenos Aires, Argentina, 5Hospital Materno Infantil de San Isidro, Department of Obstetrics and Gynaecology, San Isidro, Argentina, 6University Hospital, University Basel, Department of Obstetrics and Gynaecology, Basel, Switzerland, 7Hospital Materno Infantil Ramón Sardá, Department of Obstetrics and Gynaecology, Buenos Aires, Argentina, 8University Medical Center Utrecht, Julius Center for Health Sciences and Primary Care, Utrecht, Netherlands
OBJECTIVE: Threatened preterm labor (tPTL) is a common complication of pregnancy. However, identification of women at high risk for early delivery is difficult and its clinical definition differs between countries, which result in different preterm birth (PTB) rates between tPTL populations in those countries. Our objective was to assess whether there was a difference in risk for PTB after tPTL, and in effectiveness of progesterone between two tPTL populations. STUDY DESIGN: We performed a secondary analysis of an RCT conducted in Argentina and Switzerland that studied the association between vaginal progesterone and PTB in women with tPTL between 24 and 34 weeks (4P-trial NCT00536003). We performed Cox proportional hazards analysis to compare time-to-delivery, specifically within 7 and 14 days and before 34 and 37 weeks, between progesterone and placebo. Differences in treatment effects between countries were assessed by adding a treatment-country interaction term, and subsequent stratified analysis within countries. Analysis was adjusted for baseline differences between populations. We censored women with iatrogenic onset of labor at moment of delivery or those reaching 34 or 37 weeks. RESULTS: A total of 379 women were analyzed. Swiss (n¼172) and Argentinian (n¼207) women differed on age, weight, ethnicity, social class, parity and anatomical risk factors, but overall PTB risks were similar. There were significant country-treatment interactions for PTB within 14 days and before 34 and 37 weeks (p-values: 0.037, 0.005 and 0.025). Stratified analysis showed that in Switzerland progesterone use increased the risk for PTB within 14 days, and before 34 and 37 weeks with an adjusted HR of 4.3 (95% CI 1.2 15.8), 15.8 (95% CI 2.1 - 120.3) and 2.7 (95% CI 1.4 - 5.2), respectively. (See table) In Argentina these differences were not found. CONCLUSION: In women with tPTL effects of progesterone vary, even after adjustment of population differences. Population differences should be considered in multicenter trials.
*The odds ratio (OR) expresses the risk of sPTB in the 2nd pregnancy in women who delivered a preterm girl as compared to those who delivered a preterm boy in the 1st pregnancy. {Adjusted for: gender second pregnancy, birth weight, ART, low SES, ethnicity (Non White European), maternal age <25 year, interpregnancy interval (0-25 percentile,50-75 percentile,75-100 percentile) all in second pregnancy.
S386 American Journal of Obstetrics & Gynecology Supplement to JANUARY 2015