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Delivery mode and severe maternal and neonatal morbidity among singleton term breech births: A population-based cohort study

  • Vendela Fuxe
    Affiliations
    Department of Clinical Sciences, Division of Obstetrics and Gynecology, Karolinska Institutet, Danderyd Hospital, S-182 88 Stockholm, Sweden
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  • Sophia Brismar Wendel
    Affiliations
    Department of Clinical Sciences, Division of Obstetrics and Gynecology, Karolinska Institutet, Danderyd Hospital, S-182 88 Stockholm, Sweden
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  • Nina Bohm-Starke
    Affiliations
    Department of Clinical Sciences, Division of Obstetrics and Gynecology, Karolinska Institutet, Danderyd Hospital, S-182 88 Stockholm, Sweden
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  • Hanna Mühlrad
    Correspondence
    Corresponding author at: Department of Clinical Sciences, Division of Obstetrics and Gynecology, Karolinska Institutet, Danderyd Hospital, S-182 88 Stockholm, Sweden.
    Affiliations
    Department of Clinical Sciences, Division of Obstetrics and Gynecology, Karolinska Institutet, Danderyd Hospital, S-182 88 Stockholm, Sweden

    The Institute for Evaluation of Labor Market and Education Policy (IFAU), S-751 20 Uppsala, Sweden
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Open AccessPublished:March 08, 2022DOI:https://doi.org/10.1016/j.ejogrb.2022.03.014

      Abstract

      Objective

      The aim of this study was to examine the association between delivery mode and severe maternal and neonatal morbidity in singleton term breech births.

      Study design

      This nationwide population-based cohort study includes 41 319 singleton term and post-term breech births (37 + 0–42 + 6 gestational weeks) in Sweden from 1998 to 2016. Data was retrieved from the Swedish Medical Birth Register. The primary outcomes were two separate composite outcomes, maternal and neonatal severe morbidity. Secondary outcomes were separate severe maternal and neonatal morbidity outcomes. Hospitalization and out-patient visits during childhood were also analyzed in ages 0–5 years. Logistic regression was used to estimate unadjusted and adjusted odds ratios (aOR) with 95% confidence intervals (CI) of severe maternal and neonatal morbidity in women with vaginal breech birth or intrapartum cesarean section. Women with a prelabor breech cesarean section was used as the reference group.

      Results

      No difference between vaginal delivery and prelabor cesarean section was seen regarding maternal morbidity. Intrapartum cesarean section was associated with elevated odds for maternal morbidity (aOR 1.27, 95% CI 1.10–1.47) compared with prelabor cesarean section. A similar result was observed for vaginal delivery and intrapartum cesarean section combined (aOR 1.29, 95% CI 1.11–1.50). Vaginal delivery was associated with higher odds for composite neonatal morbidity (aOR 1.85, CI 1.54–2.21) and most separate outcomes, as well as increased number of hospital nights and out-patient visits during first year of life, compared with prelabor cesarean section.

      Conclusions

      Prelabor cesarean section in breech births improved short-term neonatal health without increasing risks for severe maternal short-term complications.

      Keywords

      Abbreviations:

      aOR (adjusted odds ratio), BMI (body mass index), CI (confidence interval), CS (cesarean section), ICD (International classification of diseases), IVF (in-vitro fertilization), MAS (meconium aspiration syndrome), MBR (medical birth register), OR (odds ratio), NPR (national patient register), VD (vaginal delivery)

      Introduction

      The optimal mode of delivery for breech presentation is debated. Previous studies suggest that prelabor cesarean section (CS) decreases the risk of short-term infant morbidity compared with vaginal delivery (VD) [

      Hannah ME, Hannah WJ, Hewson SA, Hodnett ED, Saigal S, Willan AR. Planned caesarean section versus planned vaginal birth for breech presentation at term: a randomised multicentre trial. Term Breech Trial Collaborative Group. Lancet (London, England). 2000;356(9239):1375-83.

      ,
      • Herbst A.
      • Thorngren-Jerneck K.
      Mode of delivery in breech presentation at term: increased neonatal morbidity with vaginal delivery.
      ,

      Hofmeyr GJ, Hannah M, Lawrie TA. Planned caesarean section for term breech delivery. The Cochrane database of systematic reviews. 2015;2015(7):CD000166-CD.

      ,
      • Ekeus C.
      • Norman M.
      • Åberg K.
      • Winberg S.
      • Stolt K.
      • Aronsson A.
      Vaginal breech delivery at term and neonatal morbidity and mortality – a population-based cohort study in Sweden.
      ]. In the perhaps most influential study known as the Term Breech Trial, published in 2000, the authors concluded that prelabor CS was the safest delivery method for term breech babies [

      Hannah ME, Hannah WJ, Hewson SA, Hodnett ED, Saigal S, Willan AR. Planned caesarean section versus planned vaginal birth for breech presentation at term: a randomised multicentre trial. Term Breech Trial Collaborative Group. Lancet (London, England). 2000;356(9239):1375-83.

      ]. Following the publication of the Term Breech Trial, the rates of CS among breech births substantially increased worldwide [
      • Vlemmix F.
      • Bergenhenegouwen L.
      • Schaaf J.M.
      • Ensing S.
      • Rosman A.N.
      • Ravelli A.C.J.
      • et al.
      Term breech deliveries in the Netherlands: did the increased cesarean rate affect neonatal outcome? A population-based cohort study.
      ].
      A number of studies have questioned the results presented in the Term Breech Trial [

      Hofmeyr GJ, Hannah M, Lawrie TA. Planned caesarean section for term breech delivery. The Cochrane database of systematic reviews. 2015;2015(7):CD000166-CD.

      ,
      • Bjellmo S.
      • Andersen G.L.
      • Martinussen M.P.
      • Romundstad P.R.
      • Hjelle S.
      • Moster D.
      • et al.
      Is vaginal breech delivery associated with higher risk for perinatal death and cerebral palsy compared with vaginal cephalic birth? Registry-based cohort study in Norway.
      ,
      • Goffinet F.
      • Carayol M.
      • Foidart J.-M.
      • Alexander S.
      • Uzan S.
      • Subtil D.
      • et al.
      Is planned vaginal delivery for breech presentation at term still an option? Results of an observational prospective survey in France and Belgium.
      ], and a 2-year follow-up study found no difference in child outcomes between prelabor CS and VD [
      • Whyte H.
      • Hannah M.E.
      • Saigal S.
      • Hannah W.J.
      • Hewson S.
      • Amankwah K.
      • et al.
      Outcomes of children at 2 years after planned cesarean birth versus planned vaginal birth for breech presentation at term: The International Randomized Term Breech Trial.
      ]. Vaginal breech births are performed in many settings provided that certain selection criteria are fulfilled [
      • Bjellmo S.
      • Andersen G.L.
      • Martinussen M.P.
      • Romundstad P.R.
      • Hjelle S.
      • Moster D.
      • et al.
      Is vaginal breech delivery associated with higher risk for perinatal death and cerebral palsy compared with vaginal cephalic birth? Registry-based cohort study in Norway.
      ,
      • Goffinet F.
      • Carayol M.
      • Foidart J.-M.
      • Alexander S.
      • Uzan S.
      • Subtil D.
      • et al.
      Is planned vaginal delivery for breech presentation at term still an option? Results of an observational prospective survey in France and Belgium.
      ,
      • Macharey G.
      • Toijonen A.
      • Hinnenberg P.
      • Gissler M.
      • Heinonen S.
      • Ziller V.
      Term cesarean breech delivery in the first pregnancy is associated with an increased risk for maternal and neonatal morbidity in the subsequent delivery: a national cohort study.
      ,

      Azria E, Meaux J-P, Khoshnood B, Alexander S, Subtil D, Goffinet F. Factors associated with adverse perinatal outcomes for term breech fetuses with planned vaginal delivery. Am J Obstet Gynecol 2012;207:285.e1-9.

      ]. It has also been argued that CS compared with VD increases the risk of short-term maternal complications associated with surgery [

      Sanchez-Ramos L, Wells T, Adair C, Arcelin G, Kaunitz AM, Wells D. Route of breech delivery and maternal and neonatal outcomes. International journal of gynaecology and obstetrics: the official organ of the International Federation of Gynaecol Obstetr 2001;73:7-14.

      ]. Thus, the potential benefits of CS for neonates might be at the cost of maternal health. Meanwhile, all vaginal deliveries are associated with risk of perineal injuries, which can impact postpartum maternal health and quality of life [
      • Gommesen D.
      • Nøhr E.
      • Qvist N.
      • Rasch V.
      Obstetric perineal tears, sexual function and dyspareunia among primiparous women 12 months postpartum: A prospective cohort study.
      ,
      • LaCross A.
      • Groff M.
      • Smaldone A.
      Obstetric Anal Sphincter Injury and Anal Incontinence Following Vaginal Birth: A Systematic Review and Meta-Analysis.
      ].
      Previous studies on the benefits and risks associated with CS for breech births have typically focused on either maternal or neonatal outcomes [
      • Herbst A.
      • Thorngren-Jerneck K.
      Mode of delivery in breech presentation at term: increased neonatal morbidity with vaginal delivery.
      ,
      • Ekeus C.
      • Norman M.
      • Åberg K.
      • Winberg S.
      • Stolt K.
      • Aronsson A.
      Vaginal breech delivery at term and neonatal morbidity and mortality – a population-based cohort study in Sweden.
      ,
      • Pallasmaa N.
      • Ekblad U.
      • Aitokallio-Tallberg A.
      • Uotila J.
      • Raudaskoski T.
      • Ulander V.-M.
      • et al.
      Cesarean delivery in Finland: Maternal complications and obstetric risk factors.
      ]. There is also insufficient knowledge regarding long-term outcomes of singleton term breech deliveries, for mothers and children. The aim of this study was to assess the association between mode of delivery and severe short-term maternal and neonatal morbidity in singleton term breech births from 1998 to 2016 in Sweden. We also aimed to examine the association between delivery mode and long-term follow-ups for the children, defined as hospitalizations and outpatient visits up to age five.

      Material and methods

      Study cohort

      Data for this nationwide register-based cohort study was obtained from the Swedish Medical Birth Register (MBR), provided by the National Board of Health and Welfare. The register includes information on pregnancy, delivery and postpartum care covering approximately 98% of all births beyond 22 gestational weeks in Sweden. Detailed data on maternal and neonatal characteristics was collected prospectively in standardized forms, including medical diagnoses classified according to International Classification of Diseases 10 (ICD-10) and procedures (KVÅ-codes), and forwarded automatically to the register [

      National Board of Health and Welfare of Sweden. The Swedish Medical Birth Register. Stockholm: Swedish National Board of Health and Welfare; 2019 [updated 2019 May 7; cited 2020 Apr 5 ]. Available from: https://www.socialstyrelsen.se/en/statistics-and-data/registers/register-information/the-swedish-medical-birth-register/.

      ]. Hospitalization and outpatient visits for infants up to the age of five years were retrieved from the National Patient Register (NPR). Data from MBR, NPR, and information regarding maternal education level from Statistics Sweden, were linked using unique personal identification numbers.
      For our sample selection we included all singleton, term and post-term breech births (37 + 0 to 42 + 6 weeks) in Sweden during 1998–2016 (Fig. 1). Antepartum stillbirths (n = 102, 0.2%) and births without information on educational attainment, body mass index (BMI), maternal age, country of birth, smoking in early pregnancy, parity, and hospital identifier (n = 5668, 12%) were excluded from our sample. This resulted in 41 319 births (Fig. 1).

      Exposures

      We aimed to compare maternal and neonatal severe morbidity across modes of delivery: vaginal breech birth, intrapartum CS and prelabor CS. Intended mode of delivery was defined by mode of onset, reported as induction of labor, spontaneous onset, and CS. Deliveries starting with CS were considered prelabor CS, while deliveries starting with induction of labor (n = 754) or spontaneous onset, but ending with CS, were used as a proxy for intrapartum CS during trial of labor in breech. Additionally, CS with the following conditions were considered to have followed trial of labor and were thus classified as intrapartum CS: inadequate contractions, medical induction, failed attempted vaginal delivery, fetal distress, umbilical cord complications, and excessive bleeding during labor (Table S1).

      Outcome measures

      The primary outcomes of this study were two separate composite outcomes, maternal and neonatal severe morbidity. Secondary outcomes were the separate maternal and neonatal morbidity outcomes (Table S2) and number of hospital nights and outpatient visits for each child between ages 0–5 (nights at the neonatal intensive care unit during the first 28 days of life was included in ages 0–1). The chosen outcomes were based on previously conducted studies on obstetric management [

      Hannah ME, Hannah WJ, Hewson SA, Hodnett ED, Saigal S, Willan AR. Planned caesarean section versus planned vaginal birth for breech presentation at term: a randomised multicentre trial. Term Breech Trial Collaborative Group. Lancet (London, England). 2000;356(9239):1375-83.

      ,
      • Goffinet F.
      • Carayol M.
      • Foidart J.-M.
      • Alexander S.
      • Uzan S.
      • Subtil D.
      • et al.
      Is planned vaginal delivery for breech presentation at term still an option? Results of an observational prospective survey in France and Belgium.
      ,

      Wennerholm U-B, Saltvedt S, Wessberg A, Alkmark M, Bergh C, Wendel SB, et al. Induction of labour at 41 weeks versus expectant management and induction of labour at 42 weeks (SWEdish Post-term Induction Study, SWEPIS): multicentre, open label, randomised, superiority trial. BMJ (Clinical research ed). 2019;367:l6131-l.

      ].
      Severe maternal morbidity included: maternal death, non-planned hysterectomy, severe hemorrhage, hemostatic surgery, venous thromboembolism, maternal sepsis, obstetric anal sphincter injuries including third- (>50% muscle injury) and fourth degree perineal injuries, uterine rupture, and anesthesia complications based on ICD-codes (Table S2).
      Severe neonatal morbidity included: intrapartum stillbirth, asphyxia at delivery (based on ICD-codes, see Table S2), hypoxic ischemic encephalopathy grade 2–3, intracranial hemorrhage, neonatal convulsions, respiratory distress and meconium aspiration syndrome, invasive mechanical ventilation, shoulder dystocia, therapeutic hypothermia, pneumonia, sepsis, birth trauma, brachial plexus injury, transient hypoglycemia < 2.2 mmol/l based on ICD-codes, Apgar score < 4 at five minutes and cardiorespiratory resuscitation (intubation, ventilation or heart compressions) based on standardized forms (Table S2).

      Collected characteristics

      Maternal and neonatal characteristics included: maternal age (grouped into < 25, 25–29, 30–34, 35–39, and ≥ 40 years), maternal education level (elementary school, high school, university), BMI (≤25.0, 25.1–30.0, >30.0 kg/m2), maternal height (</≥160 cm), country of birth (Sweden/not Sweden), smoking in early pregnancy (yes/no), preeclampsia/gestational hypertension (based on ICD-codes, see Table 1), gestational diabetes, parity (nullipara, primipara, multipara), in vitro fertilization (IVF, yes/no), delivery at university hospital (yes/no), neonatal birthweight (grouped into < 2500, 2500–3499, 3500–4499, ≥4500 g), gestational age (grouped into 37 + 0–38 + 6, 39 + 0–40 + 6, 41 + 0–42 + 6 weeks), fetal malformation (based on ICD-codes), small for gestational age [
      • Maršál K.
      • Persson P.-H.
      • Larsen T.
      • Lilja H.
      • Selbing A.
      • Sultan B.
      Intrauterine growth curves based on ultrasonically estimated foetal weights.
      ] and child gender (boy/girl) based on standardized forms (Table 1).
      Table 1Maternal and neonatal characteristics in breech births across delivery modes.
      Vaginal delivery

      n = 3 791
      Intrapartum CS

      n = 10 589
      Prelabor CS

      n = 26 939
      N%N%N%P-value
      Maternal characteristics

      Age group (years)
      <2547212.5136912.9286610.6<0.01
      25–29131034.6343832.5804129.8<0.001
      30–34138536.5371935.1981136.40.13
      35–3953014.0169716.0504518.7<0.001
      ≥40942.53663.511764.40.099
      Education
      Elementary school3549.3107210.121978.2<0.01
      High school167344.1440541.610,75339.9<0.001
      University176446.5511248.313,98951.9<0.001
      BMI (kg/m2)
      ≤25.0257367.9666663.016,69062.0<0.001
      25.1–30.081621.5250223.6645924.0<0.05
      >30.02827.4112610.6310211.5<0.001
      Maternal height < 160 cm3138.3147914.0329212.2<0.001
      Born in Sweden317383.7859481.222,33382.9<0.05
      Tobacco use3288.78347.919137.10.202
      Preeclampsia
      (ICD-10 codes O13.9, O14.0, 014.1, O14.1A, O14.1B, O14.1X, O14.2, O14.9), gestational diabetes (ICD-10 codes O24.4, O24.4A, O24.4B).
      581.52472.39063.40.087
      Diabetes
      (ICD-10 codes O24.4, O24.4A, O24.4B).
      130.3960.93091.10.708
      Parity
      Nulliparous181447.9690765.217,45864.8<0.001
      Primiparous136235.9250523.7662824.6<0.001
      Multiparous61516.2117711.1285310.6<0.001
      IVF541.43403.212854.8<0.001
      Delivery in university hospital167344.1519749.114,16752.6<0.001
      Neonatal characteristics
      Birthweight (g)
      <2500852.23483.36152.30.301
      2500–3499248165.4650261.415,83058.8<0.001
      3500–4499120731.8354633.510,03437.2<0.001
      ≥4500180.51931.84601.70.431
      Gestational age (weeks)
      37 + 0–38 + 6110829.2546151.615,18156.4<0.001
      39 + 0–40 + 6205754.3397537.510,86140.3<0.001
      41 + 0–42 + 662616.5115310.98973.3<0.001
      Malformation
      (ICD-10 codes Q00-Q99).
      3589.49178.721067.80.165
      Small for gestational age
      Defined according to Marsal et al 1996 (17).
      1463.93223.05932.20.160
      Male sex169444.7499247.112,39246.00.056
      CS, cesarean section; n/N, number; BMI, body mass index; IVF, in vitro fertilization.
      a (ICD-10 codes O13.9, O14.0, 014.1, O14.1A, O14.1B, O14.1X, O14.2, O14.9), gestational diabetes (ICD-10 codes O24.4, O24.4A, O24.4B).
      b (ICD-10 codes O24.4, O24.4A, O24.4B).
      c (ICD-10 codes Q00-Q99).
      d Defined according to Marsal et al 1996 (17).

      Statistics

      Data analyses were carried out using STATA 14.0 (StataCorp. 2015). We examined distributional differences in maternal and neonatal characteristics across delivery modes with Kruskal-Wallis tests. Covariates with significant differences (p < 0.05) were considered potential confounders. Maternal and neonatal morbidity by delivery mode was assessed using logistic regressions presented as odds ratio (OR) and adjusted OR (aOR) with 95% confidence intervals (CI) adjusted for maternal age, education level, BMI, maternal height, born in Sweden, parity, IVF, delivery at university hospital, gestational age, child gender and year of birth. VD and intrapartum CS were analyzed separately as well as combined (VD + intrapartum CS) as a surrogate for intended vaginal delivery. Prelabor CS was used as reference. The association between delivery mode and number of hospital nights and outpatient visits was assessed using linear ordinary least squares regressions. In all regressions, the standard errors were clustered at the hospital level to account for serial correlation within hospitals.
      For extremely rare outcomes (maternal death, non-planned hysterectomy, and therapeutic hypothermia) and outcomes unique to VD (perineal injuries), a separate regression could not be estimated. Sensitivity analysis was conducted by calculating the unadjusted OR for observations with missing data and showed consistent results with the main results (Table S3).

      Ethical approval

      The project was approved by the Swedish Ethical Review Authority in 2020–03-09 (2019–06250).

      Results

      Mode of delivery among singleton breech births changed over the study period 1998 to 2016, with a clear increase of prelabor CS and a corresponding decrease in VD after 2000 (Fig. 2). Women with VD and intrapartum CS were in general younger, of normal weight, less educated and less likely to have conceived by IVF or to have preeclampsia or diabetes compared with women with prelabor CS (Table 1). Women born outside Sweden were more common in the intrapartum CS group (Table 1).
      Figure thumbnail gr2
      Fig. 2Trends in delivery mode among singleton term breech births in Sweden 1998–2016.
      Individual outcomes of severe maternal and neonatal morbidity were rare (Table 2). The adjusted risk of severe maternal morbidity among breech births was similar in women with VD compared with prelabor CS (Table 3). Intrapartum CS was associated with increased risk of severe maternal morbidity compared with prelabor CS (Table 3). The risk of ‘maternal sepsis’ and ‘uterine rupture and other obstetric injuries’ were individually increased in the intrapartum CS group (Table 3). VD and intrapartum CS combined carried an increased risk of severe maternal morbidity compared with prelabor CS (Table 3).
      Table 2Severe maternal and neonatal outcomes in breech births across delivery modes.
      Vaginal delivery

      n = 3 791
      Intrapartum CS

      n = 10 589
      Prelabor CS

      n = 26 939
      N%N%N%
      Maternal morbidity

      (composite outcome)
      651.711741.643521.31
      Maternal morbidity

      (separate outcomes)
      Maternal death0010.0110.00
      Hysterectomy0050.05220.08
      Severe hemorrhage
      Blood transfusion + blood loss > 1000 ml or hemorrhage with coagulopathy.
      190.50670.631720.64
      Hemostatic surgery
      Surgical intervention such as uterine or vaginal tamponade, uterine compression sutures, embolization and re-operation due to complications.
      40.11310.29670.25
      Venous thromboembolism20.0550.05140.05
      Maternal sepsis70.18590.56910.34
      Third degree perineal lacerations (≥50%)240.630000
      Fourth degree perineal lacerations70.180000
      Uterine rupture and other obstetric injuries
      Other obstetric injuries during vaginal versus cesarean delivery (see Table S1 in supporting information).
      10.03210.20180.07
      Anesthesia complications10.0340.0490.03
      Neonatal morbidity

      (composite outcome)
      2827.445645.3313625.06
      Neonatal morbidity

      (separate outcomes)
      Intrapartum stillbirth40.1120.0200
      Asphyxia at delivery751.98380.36180.07
      Hypoxic ischemic encephalopathy grade 2–350.13100.0990.03
      Intracranial hemorrhage60.1640.0440.01
      Neonatal convulsions120.32180.17260.10
      Respiratory distress and MAS531.401521.444521.68
      Mechanical ventilation50.1330.03190.07
      Shoulder dystocia000000
      Therapeutic hypothermia0010.0100
      Pneumonia10.0370.07190.07
      Sepsis110.29390.37410.15
      Birth trauma
      Fractures, neurologic injury, retinal hemorrhage or facial nerve palsy, pulmonary hemorrhage, pneumothorax.
      581.53570.54880.33
      Brachial plexus injury220.5840.0480.03
      Hypoglycemia < 2.2 mmol/l691.822942.787672.85
      Apgar score < 4 at five minutes471.25260.25200.07
      Cardiorespiratory resuscitation541.42420.40460.17
      CS, cesarean section; n/N, number; MAS, meconium aspiration syndrome.
      a Blood transfusion + blood loss > 1000 ml or hemorrhage with coagulopathy.
      b Surgical intervention such as uterine or vaginal tamponade, uterine compression sutures, embolization and re-operation due to complications.
      c Other obstetric injuries during vaginal versus cesarean delivery (see Table S1 in supporting information).
      d Fractures, neurologic injury, retinal hemorrhage or facial nerve palsy, pulmonary hemorrhage, pneumothorax.
      Table 3Odds ratio and adjusted odds ratio for severe maternal and neonatal composite and separate outcomes in term breech births with prelabor cesarean section as reference.
      Vaginal delivery

      n = 3 791
      Intrapartum CS

      n = 10 589
      VD and intrapartum CS

      n = 14 380
      Severe maternal morbidity
      OR [95% CI]
      Composite outcome1.32[0.91–1.91]1.26[1.07–1.48]1.28[1.08–1.51]
      aOR [95% CI]
      Composite outcome1.36[0.91–2.03]1.27[1.10–1.47]1.29[1.11–1.50]
      Severe hemorrhage
      Blood transfusion + blood loss > 1000 ml or hemorrhage with coagulopathy.
      0.95[0.57–1.58]1.03[0.82–1.29]1.01[0.80–1.28]
      Hemostatic surgery
      Surgical intervention such as uterine or vaginal tamponade, uterine compression sutures, embolization and re-operation due to complications.
      0.47[0.15–1.45]1.23[0.79–1.91]1.06[0.72–1.54]
      Venous thromboembolism1.07[0.22–5.26]0.94[0.31–2.88]0.97[0.36–2.60]
      Maternal sepsis0.52[0.20–1.39]1.62[1.23–2.14]1.37[1.04–1.81]
      Uterine rupture and other obstetric injuries
      Other obstetric injuries during vaginal versus cesarean delivery (see Table S1 in supporting information).
      0.40[0.05–3.40]2.94[1.43–6.04]2.37[1.15–4.87]
      Anesthesia complications0.67[0.09–4.71]1.05[0.31–3.59]0.95[0.33–2.76]
      Severe neonatal morbidity
      OR [95% CI]
      Composite outcome1.51[1.31–1.75]1.06[0.95–1.18]1.18[1.06–1.30]
      aOR [95% CI]
      Composite outcome1.85[1.54–2.21]1.10[0.99–1.23]1.26[1.13–1.39]
      Asphyxia at delivery29.80[17.34–51.23]5.46[2.89–10.30]10.45[6.49–16.81]
      Hypoxic ischemic encephalopathy 2–35.87[1.97–17.48]3.07[1.30–7.26]3.59[1.57–8.23]
      Intracranial hemorrhage12.09[3.50–41.79]2.66[0.82–8.62]4.60[1.71–12.41]
      Neonatal convulsions3.98[1.83–8.65]1.88[0.94–3.75]2.31[1.30–4.09]
      Respiratory distress and MAS0.94[0.69–1.27]0.88[0.74–1.04]0.89[0.75–1.05]
      Mechanical ventilation2.83[1.36–5.92]0.43[0.16–1.18]0.88[0.48–1.63]
      Cardiorespiratory resuscitation13.45[8.47–21.37]2.56[1.69–3.89]4.46[3.14–6.35]
      Apgar score < 4 at five minutes20.55[10.50–40.21]3.44[1.93–6.13]6.74[3.94–11.53]
      Pneumonia0.26[0.04–1.62]0.86[0.39–1.90]0.68[0.34–1.34]
      Sepsis1.86[0.75–4.58]2.41[1.48–3.91]2.29[1.39–3.75]
      Birth trauma
      Fractures, neurologic injury, retinal hemorrhage or facial nerve palsy, pulmonary hemorrhage, pneumothorax.
      5.01[3.61–6.95]1.70[1.24–2.33]2.41[1.91–3.05]
      Brachial plexus injury21.16[9.07–49.38]1.28[0.35–4.68]5.35[2.32–12.35]
      Hypoglycemia0.89[0.67–1.17]1.02[0.91–1.15]1.00[0.89–1.11]
      VD, vaginal delivery; CS, cesarean section; OR, odds ratio; aOR, adjusted odds ratio; CI, confidence interval; MAS, meconium aspiration syndrome.
      The following cofounding factors were adjusted for in regression analyses: maternal age in years (<25, 25–29, 30–34, 35–39, ≥40), maternal education level, BMI (<25.0, 25.1–30.0, >30.0), maternal height (<160 cm), born in Sweden, parity, IVF, delivery at university hospital, gestational age in weeks (37 + 0–38 + 6, 39 + 0–40 + 6, 41 + 0–42 + 6), child gender and year of birth.
      a Blood transfusion + blood loss > 1000 ml or hemorrhage with coagulopathy.
      b Surgical intervention such as uterine or vaginal tamponade, uterine compression sutures, embolization and re-operation due to complications.
      c Other obstetric injuries during vaginal versus cesarean delivery (see Table S1 in supporting information).
      d Fractures, neurologic injury, retinal hemorrhage or facial nerve palsy, pulmonary hemorrhage, pneumothorax.
      The risk of composite severe morbidity was increased in neonates after VD compared with prelabor CS (Table 3). This also applied to several separate neonatal morbidity outcomes (Table 3). Similar results were found for VD and intrapartum CS combined, while intrapartum CS carried the same risk of severe neonatal morbidity as prelabor CS (Table 3).
      Number of hospital nights and outpatient visits for children born in breech was elevated after VD during the first year of life compared with prelabor CS, but this association disappeared during ages 1–5 (Fig. 3a and 3b).
      Figure thumbnail gr3
      Fig. 3Fig. 3a. Association between delivery mode and number of outpatient visits among singleton term and post-term breech born infants with prelabour cesarean section as reference (grey line). Fig. 3b. Association between delivery mode and number of hospital nights among singleton term and post-term breech born infants with prelabour cesarean section as reference (grey line).

      Discussion

      In this nationwide cohort study of over 41 000 term and post-term breech births, we found a similar rate of severe maternal morbidity between VD and prelabor CS. When combining intrapartum CS with VD we found a slightly increased risk of severe maternal morbidity. Moreover, our results confirm that for singleton breech babies, the short-term severe neonatal morbidity is reduced with prelabor CS [

      Hannah ME, Hannah WJ, Hewson SA, Hodnett ED, Saigal S, Willan AR. Planned caesarean section versus planned vaginal birth for breech presentation at term: a randomised multicentre trial. Term Breech Trial Collaborative Group. Lancet (London, England). 2000;356(9239):1375-83.

      ,
      • Herbst A.
      • Thorngren-Jerneck K.
      Mode of delivery in breech presentation at term: increased neonatal morbidity with vaginal delivery.
      ,

      Hofmeyr GJ, Hannah M, Lawrie TA. Planned caesarean section for term breech delivery. The Cochrane database of systematic reviews. 2015;2015(7):CD000166-CD.

      ,
      • Ekeus C.
      • Norman M.
      • Åberg K.
      • Winberg S.
      • Stolt K.
      • Aronsson A.
      Vaginal breech delivery at term and neonatal morbidity and mortality – a population-based cohort study in Sweden.
      ,
      • Vlemmix F.
      • Bergenhenegouwen L.
      • Schaaf J.M.
      • Ensing S.
      • Rosman A.N.
      • Ravelli A.C.J.
      • et al.
      Term breech deliveries in the Netherlands: did the increased cesarean rate affect neonatal outcome? A population-based cohort study.
      ]. We also found that child health, measured by hospital visits and nights after the first year of life, is not associated with delivery mode.
      In the Term Breech Trial, adverse maternal outcomes were similar in women with intended VD and prelabor CS for breech [

      Hannah ME, Hannah WJ, Hewson SA, Hodnett ED, Saigal S, Willan AR. Planned caesarean section versus planned vaginal birth for breech presentation at term: a randomised multicentre trial. Term Breech Trial Collaborative Group. Lancet (London, England). 2000;356(9239):1375-83.

      ]. However, a Cochrane meta-analysis and several observational studies have found increased maternal morbidity in prelabor CS compared to VD [

      Hofmeyr GJ, Hannah M, Lawrie TA. Planned caesarean section for term breech delivery. The Cochrane database of systematic reviews. 2015;2015(7):CD000166-CD.

      ,

      Sanchez-Ramos L, Wells T, Adair C, Arcelin G, Kaunitz AM, Wells D. Route of breech delivery and maternal and neonatal outcomes. International journal of gynaecology and obstetrics: the official organ of the International Federation of Gynaecol Obstetr 2001;73:7-14.

      ,
      • Irion O.
      • Hirsbrunner Almagbaly P.
      • Morabia A.
      Planned vaginal delivery versus elective caesarean section: a study of 705 singleton term breech presentations.
      ,
      • Mattila M.
      • Rautkorpi J.
      • Heikkinen T.
      Pregnancy outcomes in breech presentation analyzed according to intended mode of delivery.
      ]. The observed increased risk in the combined group of intrapartum CS and VD in our study was mostly driven by intrapartum CS, and notably ‘maternal sepsis’ and ‘uterine rupture and other obstetric injuries’.
      Previous studies on the preferred delivery mode among breech births for long-term health are scarce and provide mixed evidence. For instance, while a meta-study found increased medical issues among infants allocated to planned CS at two years of age [

      Hofmeyr GJ, Hannah M, Lawrie TA. Planned caesarean section for term breech delivery. The Cochrane database of systematic reviews. 2015;2015(7):CD000166-CD.

      ], two Nordic studies found that the increase in planned C-sections (attributed to the publication of the TBT) led to a reduction in GP visits ages 1–3 in Denmark [
      • Jensen V.M.
      • Wüst M.
      Can Caesarean section improve child and maternal health? The case of breech babies.
      ] and a reduction of inpatient visits during ages 1–10 in Sweden [
      • Mühlrad H.
      Cesarean sections for high-risk births: health, fertility, and labor market outcomes.
      ]. Our results, however, mimic those of the two-year follow up study of the TBT [
      • Whyte H.
      • Hannah M.E.
      • Saigal S.
      • Hannah W.J.
      • Hewson S.
      • Amankwah K.
      • et al.
      Outcomes of children at 2 years after planned cesarean birth versus planned vaginal birth for breech presentation at term: The International Randomized Term Breech Trial.
      ], with no significant impact on in- or outpatient visits during ages 1–5.
      The major strengths of our study include the richness and coverage of linked Swedish register data and the large sample, which enabled us to more completely examine the risks of both composite and individual rare maternal and neonatal complications in breech births, than previous Swedish studies [
      • Herbst A.
      • Thorngren-Jerneck K.
      Mode of delivery in breech presentation at term: increased neonatal morbidity with vaginal delivery.
      ,
      • Ekeus C.
      • Norman M.
      • Åberg K.
      • Winberg S.
      • Stolt K.
      • Aronsson A.
      Vaginal breech delivery at term and neonatal morbidity and mortality – a population-based cohort study in Sweden.
      ,
      • Mühlrad H.
      Cesarean sections for high-risk births: health, fertility, and labor market outcomes.
      ]. In addition, our analysis included subsequent health outcomes in children.
      The major limitation of this study involves the risk of misclassification regarding intended delivery mode, as this information is insufficiently classified in the register. An intended prelabor CS could be misclassified as an intrapartum CS, for example when labor had commenced earlier than expected. This would lead to a possible underestimation of the observed risks in the intrapartum CS group.
      Moreover, the indication and timing of the CS are not directly available in the register and may only be deducted from ICD-codes at discharge. Although we were unable to see the proportion of CS performed during second stage, this group could contribute to an elevated risk of severe maternal morbidity in intrapartum CS alone or combined with VD, compared to prelabor CS. Concerning VD, our data does not reveal at what point the breech presentation was identified. Breech presentations detected late in labor are likely associated with worse outcomes than in planned VD, causing a potential overestimation of especially neonatal complications in the VD group.
      When counselling women on planned mode of delivery it is important to consider the absolute prevalence of adverse outcomes and the potential risks in future births after a previous CS. For example, uterine scarring increases the risk of uterine rupture, placenta previa and placenta accreta, entailing potentially life-threatening complications for the mother and subsequent children [

      Wängberg Nordborg J AM, Carlsson Y, Eriksson Orrskog M, Jivegård L, Stadig I, et al. Term breech presentation - Caesarean section versus vaginal delivery (Sätesändläge i fullgången tid - kejsarsnitt eller vaginal förlossning?) [Internet]. Göteborg: Västra Götalandsregionen, Sahlgrenska Universitetssjukhuset, HTA-centrum; 2017 [cited 2021 Jan 20]. Available from: https://alfresco-offentlig.vgregion.se/alfresco/service/vgr/storage/node/content/workspace/SpacesStore/734b7fde-a749-4659-8ca6-c66cc7a52702/2017_98%20HTA-rapport%20S%C3%A4tesbjudning.pdf?a=false&guest=true.

      ]. Previous studies on the general population have found CS to increase future risks for mothers and neonates [
      • Keag O.E.
      • Norman J.E.
      • Stock S.J.
      • Myers J.E.
      Long-term risks and benefits associated with cesarean delivery for mother, baby, and subsequent pregnancies: Systematic review and meta-analysis.
      ,

      Wagner M. Choosing Caesarean Section. Midwifery today with international midwife. 2001;356:26-9.

      ,
      • Landon M.B.
      • Hauth J.C.
      • Leveno K.J.
      • Spong C.Y.
      • Leindecker S.
      • Varner M.W.
      • et al.
      Maternal and Perinatal Outcomes Associated With a Trial of Labor After Prior Cesarean Delivery.
      ]. Yet, a Swedish study on the impact of CS for breech presentation specifically found no significant impact of CS on maternal morbidity at subsequent births [
      • Mühlrad H.
      Cesarean sections for high-risk births: health, fertility, and labor market outcomes.
      ]. More research is required and there is an admitted knowledge gap regarding the risks of previous CS versus previous VD for breech [

      Wängberg Nordborg J AM, Carlsson Y, Eriksson Orrskog M, Jivegård L, Stadig I, et al. Term breech presentation - Caesarean section versus vaginal delivery (Sätesändläge i fullgången tid - kejsarsnitt eller vaginal förlossning?) [Internet]. Göteborg: Västra Götalandsregionen, Sahlgrenska Universitetssjukhuset, HTA-centrum; 2017 [cited 2021 Jan 20]. Available from: https://alfresco-offentlig.vgregion.se/alfresco/service/vgr/storage/node/content/workspace/SpacesStore/734b7fde-a749-4659-8ca6-c66cc7a52702/2017_98%20HTA-rapport%20S%C3%A4tesbjudning.pdf?a=false&guest=true.

      ].
      Finally, our findings are based on Swedish data and may be generalizable to countries with similar populations and healthcare systems such as other Nordic countries and possibly northern European countries but may not be generalized to low-income countries with limited access to cesarean section.

      Conclusion

      In singleton term and post-term breech births, VD or attempt thereof, increased the risk of short-term severe neonatal morbidity compared with prelabor CS. Severe maternal morbidity was not increased in VD, but in attempt thereof, compared with prelabor CS. Our results suggest that prelabor CS reduces the risks of rare, severe adverse outcomes for neonates, without compromising the health of the mother in the current birth. We found no association between delivery mode and long-term health for children ages 1–5.

      Declaration of Competing Interest

      The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper.

      Acknowledgements

      We thank Julia Savchenko at Department of Clinical Science and Education, Södersjukhuset, Karolinska Institutet and Ellika Andolf, Department of Clinical Sciences, Danderyd Hospital, Karolinska Institutet, for providing insightful and helpful comments.

      Author contributions

      Vendela Fuxe and Hanna Mühlrad have collected the data, managed the dataset, performed the analyses, summarized the results, and written the manuscript draft. Sophia Brismar Wendel and Nina Bohm-Starke have taken part in planning of the study, supervised the analyses and interpretation of the results and contributed to writing the manuscript. All authors have approved of the final version of the manuscript.

      Appendix A. Supplementary data

      The following are the Supplementary data to this article:

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      Biography

      Hanna Mühlrad received her PhD in Economics at the University at Gothenburg. She is currently a researcher at IFAU and holds a post-doc position at the Department of Clinical Sciences Danderyd Hospital, Karolinska Institutet. Mühlrad’s main research interests include health, fertility, gender and labor markets
      Vendela Fuxe is currently a medical student at Karolinska Institutet in Stockholm and will receive her Degree of Master of Science in Medicine in January 2022. She is interested in obstetrics and gynecology and started working on the current study when doing her degree project in medicine. She also works as a research assistant at the Department of Medical Epidemiology and Biostatistics (MEB) at Karolinska Institutet
      Nina Bohm Starke, MD, PhD and associate professor at the Department of Clinical Sciences, Division of Obstetrics and Gynecology, Karolinska Institutet, Danderyd Hospital, Sweden. Dr. Bohm-Starke is a senior consultant in obstetrics and gynecology at Danderyd Hospital, Stockholm, Sweden. In her clinical and scientific work, she is mostly acknowledged for her contribution to vulvovaginal disease. Her research has largely focused on biological and psychological factors, as well as treatment modalities associated with unexplained vulvar pain (vulvodynia). In her research she has experience in using Swedish register data, including the methods used in the current study
      Sophia Brismar Wendel is MD, PhD, Associate Professor affiliated to Karolinska Institutet, Stockholm, Sweden, and senior consultant in obstetrics and gynecology and labor ward lead at Danderyd Hospital, Stockholm, Sweden. She defended her thesis “HPV and progression markers in cervical intraepithelial neoplasia – clinical and diagnostic impact” at Karolinska Institutet in 2009. Her current research regards complications at childbirth. She is member of the board of the Swedish Society of Obstetrics and Gynecology, steering group member of several multicenter RCTs.