Associations between term cesarean delivery in the first pregnancy and second‐pregnancy preterm delivery

Abstract Introduction Cesarean delivery has been shown to increase the risk of preterm delivery in future pregnancies. The association could be a direct result of the procedure, or because the indications that led to the cesarean delivery also increase the risk of preterm delivery in later pregnanci...

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Main Authors: Anders Einum, Quaker E. Harmon, Linn Marie Sørbye, Roy Miodini Nilsen, Nils‐Halvdan Morken
Format: Article
Language:English
Published: Wiley 2025-01-01
Series:Acta Obstetricia et Gynecologica Scandinavica
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Online Access:https://doi.org/10.1111/aogs.14996
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author Anders Einum
Quaker E. Harmon
Linn Marie Sørbye
Roy Miodini Nilsen
Nils‐Halvdan Morken
author_facet Anders Einum
Quaker E. Harmon
Linn Marie Sørbye
Roy Miodini Nilsen
Nils‐Halvdan Morken
author_sort Anders Einum
collection DOAJ
description Abstract Introduction Cesarean delivery has been shown to increase the risk of preterm delivery in future pregnancies. The association could be a direct result of the procedure, or because the indications that led to the cesarean delivery also increase the risk of preterm delivery in later pregnancies. Material and Methods 298 901 mothers with first and second singleton deliveries from 1999 to 2020 were investigated using data from the Medical Birth Registry of Norway linked with Statistics Norway. The mothers were categorized by mode of cesarean delivery (total, emergency and planned) and vaginal delivery at term in the first pregnancy. We used log‐binomial regression models to estimate relative risks with 95% confidence intervals (CI) of iatrogenic and spontaneous preterm delivery <37 gestational weeks in the second pregnancy. Second, we explored the role of recurrent placental disease in preterm delivery by comparing estimates in mothers with placental disease in neither or both pregnancies. Results 8243 mothers (2.8%) had a preterm delivery in the second pregnancy. The adjusted relative risk (aRR) of preterm delivery was 1.24 (95% CI 1.17–1.32) after cesarean compared with vaginal delivery in the first pregnancy. The association was stronger in previous planned compared with emergency cesarean delivery (aRR 1.52, 95% CI 1.30–1.77 and aRR 1.21, 95% CI 1.14–1.29, respectively). Spontaneous preterm delivery was not associated with the previous mode of delivery; the risk was confined to iatrogenic preterm delivery after both emergency and planned cesarean delivery (aRR 1.69, 95% CI 1.52–1.87 and aRR 2.65, 95% CI 2.12–3.30, respectively). Mothers with placental disease in both pregnancies had a sixfold increased risk of preterm delivery in the second pregnancy compared with mothers with no placental disease, however, the association between mode of delivery and subsequent preterm delivery was similar in mothers with and without placental disease in the pregnancies. Conclusions Compared with vaginal term delivery in the first pregnancy, cesarean delivery increases the risk of iatrogenic, but not spontaneous preterm delivery in the next pregnancy. Although strongly associated with preterm delivery, placental disease had limited influence on the estimates.
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spelling doaj-art-1f2bfef9e93c42f2b77fb712f4fc8a252025-08-20T03:22:18ZengWileyActa Obstetricia et Gynecologica Scandinavica0001-63491600-04122025-01-011041687610.1111/aogs.14996Associations between term cesarean delivery in the first pregnancy and second‐pregnancy preterm deliveryAnders Einum0Quaker E. Harmon1Linn Marie Sørbye2Roy Miodini Nilsen3Nils‐Halvdan Morken4Department of Clinical Science University of Bergen Bergen NorwayNational Institute of Environmental Health Sciences Durham North Carolina USADepartment of Obstetrics and Gynecology Haukeland University Hospital Bergen NorwayFaculty of Health and Social Sciences Western Norway University of Applied Sciences Bergen NorwayDepartment of Clinical Science University of Bergen Bergen NorwayAbstract Introduction Cesarean delivery has been shown to increase the risk of preterm delivery in future pregnancies. The association could be a direct result of the procedure, or because the indications that led to the cesarean delivery also increase the risk of preterm delivery in later pregnancies. Material and Methods 298 901 mothers with first and second singleton deliveries from 1999 to 2020 were investigated using data from the Medical Birth Registry of Norway linked with Statistics Norway. The mothers were categorized by mode of cesarean delivery (total, emergency and planned) and vaginal delivery at term in the first pregnancy. We used log‐binomial regression models to estimate relative risks with 95% confidence intervals (CI) of iatrogenic and spontaneous preterm delivery <37 gestational weeks in the second pregnancy. Second, we explored the role of recurrent placental disease in preterm delivery by comparing estimates in mothers with placental disease in neither or both pregnancies. Results 8243 mothers (2.8%) had a preterm delivery in the second pregnancy. The adjusted relative risk (aRR) of preterm delivery was 1.24 (95% CI 1.17–1.32) after cesarean compared with vaginal delivery in the first pregnancy. The association was stronger in previous planned compared with emergency cesarean delivery (aRR 1.52, 95% CI 1.30–1.77 and aRR 1.21, 95% CI 1.14–1.29, respectively). Spontaneous preterm delivery was not associated with the previous mode of delivery; the risk was confined to iatrogenic preterm delivery after both emergency and planned cesarean delivery (aRR 1.69, 95% CI 1.52–1.87 and aRR 2.65, 95% CI 2.12–3.30, respectively). Mothers with placental disease in both pregnancies had a sixfold increased risk of preterm delivery in the second pregnancy compared with mothers with no placental disease, however, the association between mode of delivery and subsequent preterm delivery was similar in mothers with and without placental disease in the pregnancies. Conclusions Compared with vaginal term delivery in the first pregnancy, cesarean delivery increases the risk of iatrogenic, but not spontaneous preterm delivery in the next pregnancy. Although strongly associated with preterm delivery, placental disease had limited influence on the estimates.https://doi.org/10.1111/aogs.14996emergency cesarean deliveryfetal growth restrictiongestational ageiatrogenic deliveryplacentaplanned cesarean delivery
spellingShingle Anders Einum
Quaker E. Harmon
Linn Marie Sørbye
Roy Miodini Nilsen
Nils‐Halvdan Morken
Associations between term cesarean delivery in the first pregnancy and second‐pregnancy preterm delivery
Acta Obstetricia et Gynecologica Scandinavica
emergency cesarean delivery
fetal growth restriction
gestational age
iatrogenic delivery
placenta
planned cesarean delivery
title Associations between term cesarean delivery in the first pregnancy and second‐pregnancy preterm delivery
title_full Associations between term cesarean delivery in the first pregnancy and second‐pregnancy preterm delivery
title_fullStr Associations between term cesarean delivery in the first pregnancy and second‐pregnancy preterm delivery
title_full_unstemmed Associations between term cesarean delivery in the first pregnancy and second‐pregnancy preterm delivery
title_short Associations between term cesarean delivery in the first pregnancy and second‐pregnancy preterm delivery
title_sort associations between term cesarean delivery in the first pregnancy and second pregnancy preterm delivery
topic emergency cesarean delivery
fetal growth restriction
gestational age
iatrogenic delivery
placenta
planned cesarean delivery
url https://doi.org/10.1111/aogs.14996
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