This supplementary information is presented as submitted by the corresponding author. It has not been copy-edited by NTvG.
It is known that an elective caesarean section (CS) performed before a gestational age of 39+0 weeks is associated with an increased neonatal morbidity with short and long-term consequences. We were interested whether this knowledge has led to a decline in time in the incidence of elective CS before 39+0 weeks of gestation and which factors are associated with this timing.
Retrospective Cohort study
Using data from The Netherlands Perinatal Registry we analysed the incidence of all term elective CS (n=59,653), subdivided according to gestational age per week, between 2000 and 2010. Besides several patient characteristics (age, parity, ethnicity, fetal position and social economic status), we analysed specifically type of hospital (academic versus peripheral teaching hospitals versus peripheral non-teaching hospitals), hospitals subdivided according to number of deliveries per year (based on percentiles) and weekday. The number of deliveries per hospital p 75 corresponded to the number of deliveries per year of <720, 720-1400 and >1400 respectively. Trends in patient characteristics and in performing an elective CS before 39+0 weeks were analysed with regression analysis, differences between hospitals with the χ2 test. With multiple logistic regression analysis we analysed which factors were associated with performing an elective CS before 39+0 weeks.
Data of 59,653 elective CS were available for further analysis. The average age of women increased from 31.9 to 32.4 year and the percentage of woman above 35 years of age increased from 26.9% (2000) to 33.3% (2010). From 2001 the percentage of women with a Caucasian ethnicity and nulliparity decreased. Gender and birth weight didn’t show any relevant differences over the years. The percentage of neonates with a birth weight below the 10th percentile was 5.6% before and 6.7% after 39+0 weeks of gestation.
The percentage of elective CS before a gestation of 39+0 weeks significantly decreased from 56% in 2000 to 43% in 2010 (p < 0,0001), especially CS at a gestational age of 38+0-6 weeks decreased in favour of elective CS between 39+0-6 weeks of gestation. Compared to academic hospitals, in peripheral hospitals an elective SC was performed more often before 39+0 weeks; 53% in peripheral teaching hospitals, 57% in non-teaching hospitals and 46% in academic hospitals. Adjusted odds ratio’s (OR) and 95% confidence interval (CI) were respectively 1.38(1.30-1.47) for peripheral teaching hospitals and 1.55(1.46-1.65) for peripheral non-teaching hospitals. Analysing hospitals according to the number of deliveries per year, hospitals in the lower quartile had significantly higher percentages elective SC <39+0 weeks compared to hospitals in the upper quartile (respectively 60% and 52%, p<0.0001). Trend analyses according to type of hospital and number of deliveries per year in a hospital from 2000 to 2010 did not show any relevant differences over the years.
Our data provide a valid reflection on timing of elective cesarean sections in the Netherlands; unfortunately in 2010 the percentage of elective CS before 39+0 weeks of gestation is still high and performed more often in peripheral hospitals with fewer deliveries per year. The relation between an increased risk of neonatal morbidity and performing an elective SC before 39+0 weeks of gestation was demonstrated earlier in this population until 2006. In this manuscript we therefore focused on trends in timing. However, extrapolating numbers of neonatal respiratory morbidity to this cohort shows that, as a result of still performing 43-56% of elective CS before 39+0 weeks of gestation, an average of 55 additional neonates per year is exposed to the risk for iatrogenic respiratory morbidity. Long term evaluations show that children born early term (between 37+0-38+6) have a higher risk for healthcare problems (e.g. asthma) and more need for special education.
The fact that we haven’t improved timing of elective cesarean sections as much as necessary is probably multifactorial. Until March 2011 there was no Dutch guideline with regard to timing of elective cesarean sections. However, national guidelines do not influence local acting immediately. There is need for awareness and change of local protocols as was shown in several publications from the United States. As absolute numbers of neonatal mortality and morbidity are low, consciousness of risks related to timing of elective CS is lacking. Subsequently, logistic and patient factors are involved, just like fear for an intrapartum CS in which it is difficult to outweigh the maternal risks and logistic problems against stimulation of surfactant in the fetal lungs. Recent analysis showed no maternal advantage performing an elective CS between 37+0-38+6 weeks of gestation. Finally, timing >39+0 turned out to be cost effective.