Introduction
Globally, Caesarean delivery (CD) rates doubled from 12% in 2000 to
21% ( i.e. 29.7 million births) in 2015. However, evidence exists that
6.2 million CDs are performed annually without medical
indications2. While CD can be a life-saving
intervention for both the mother and the baby to reduce complications
associated with childbirth, it is also performed in situations when
neither the mother nor the fetus is at risk of complications. Increasing
maternal age at first pregnancy, increasing body mass index (BMI), fetal
malpresentation, and repeated CD (women with a previous CD) have been
noted as the main factors contributing to the increased CD
rate3-5. Although Sweden has one of the lowest CS
rates in Europe, the CD rate has also increased over the last two
decades from 15.5% in 2000 to almost 18% in 2020, with approximately
83–88% of the total increase accounting for repeat
CD6, 7. Due to the increased frequency of CD, studies
have been conducted to assess the impact of CD on subsequent pregnancy
outcomes8, particularly the risk of
stillbirth9, 10 and preterm birth11,
12.
Stillbirth, a baby born with no signs of life, is one of the most common
serious adverse pregnancy outcomes. Approximately 2 million babies were
stillborn at or after 28 weeks’ gestation in 2019, with a global rate of
13.9 per 1000 births15. In high-income countries
(HIC), stillbirth rates vary widely from 1.3 to 8.8 per 1,000
births16. A systematic review and meta-analysis
conducted in 2011 to identify important risk factors for stillbirth in
HIC reported a 21% increased odds of stillbirth (odds ratio (OR):1.21
[95% confidence interval (CI), 1.07–1.37]) in mothers with a
previous CD17. Similarly, a more recent meta-analysis
reported a 23% increased odds of stillbirth following CD (pooled
OR:1.23 [95% CI, 1.08–1.40])9. Although both
reviews reported similar findings, they were limited by high
heterogeneity due in part to variation in
the cause and timing of
stillbirth. A 2020 Norwegian cohort study also reported a slightly
higher odds of stillbirth following CD (adjusted OR (aOR):1.45 [95%
CI, 1.22–1.73])18, but the authors did not evaluate
the impact of the type of CD on the reported
associations18. Given the increasing rates of CD, a
potential association between CD, specifically unnecessary CD, and
subsequent stillbirth is of significant concern.
In pregnancies following a CD, birth can be achieved either by a repeat
planned CD, known as elective repeat caesarean section (ERCS) or
attempting a vaginal birth, known as vaginal birth after caesarean
(VBAC). Limited studies have evaluated perinatal outcomes relating to
VBAC18, 19, and evidence on the association between
VBAC and stillbirth is lacking and require further investigations.
Therefore, we conducted this population-based cohort study to
investigate if offspring in deliveries following a previous CD have a
higher risk for stillbirth than offspring where the mother had a
previous VB. We also examined the risk of stillbirth in women who had a
VBAC delivery compared to those who had an ERCS.