Delivery by caesarean section and childhood cancer: a nationwide follow‐up study in three countries

Abstract

Objective To investigate the association between delivery by caesarean section and risk of childhood cancer.Design A population-based, follow-up study using register data from three countries.Setting Denmark, Sweden and Finland.Population Children born in Denmark (1973Denmark ( -2007, Sweden and Finland (randomly selected sample of 90%, 1987-2007; n = 7 029 843).Methods Exposure was delivery by caesarean section and the outcome was childhood cancer diagnosis. Follow-up started from birth and ended at the first of the following dates: cancer diagnosis, death, emigration, day before 15th birthday or end of follow-up. Cox regression was used to obtain hazard ratios. Main outcome measures Childhood cancer diagnosis.Results A total of 882 907 (12.6%) children were delivered by caesarean section. Of these, 30.3% were elective (n = 267 603), 35.9% unplanned (n = 316 536) and 33.8% had no information on planning (n = 298 768). Altogether, 11 181 children received a cancer diagnosis. No evidence of an increased risk of childhood cancer was found for children born by caesarean section (hazard ratio, 1.05; 95% confidence interval, 0.99, 1.11). No association was found for any major type of childhood cancer, or when split by the type of caesarean section (elective/unplanned). ConclusionThe evidence does not suggest that caesarean section is a risk factor for the overall risk of childhood cancer and possibly not for subtypes of childhood cancer either.

Caesarean delivery and risk of childhood leukaemia: a pooled analysis from the Childhood Leukemia International Consortium (CLIC)

“…In this context, both null, 12,14-16 and marginally significant positive associations between ALL and overall caesarean delivery 1820 have been shown. Similarly, studies that did not distinguish between leukaemia subtypes also reported null 13,17 or small positive 37 associations. One study distinguished between emergency and prelabour caesarean delivery and reported null associations for caesarean delivery overall and for prelabour caesarean delivery in children diagnosed at age 0-14 years, but reported moderate positive associations for children aged 0-3 years between ALL—particularly B-cell ALL—and both all-caesarean deliveries and prelabour caesarean delivery.…”

“…11 An association of childhood leukaemia with caesarean delivery has not been established, although many studies might be underpowered to detect a small association. Several previous studies have reported null associations between caesarean delivery and ALL, 12–17 but findings from one study suggested increased odds of ALL after caesarean delivery. 18 Furthermore, two studies have done subgroup analyses and shown raised effect estimates when stratifying by disease subtypes or type of caesarean delivery.…”

Prelabor cesarean delivery and early-onset acute childhood leukemia risk

“…For leukemia, the results are rather contradictory, with studies showing increased or nonsignificant associations (Kaye et al, 1991;Momen et al, 2014).…”

Paediatric acute lymphoblastic leukaemia and caesarean section: A report from the United Kingdom Childhood Cancer Study (UKCCS)

“…More recently, another study reported a 2.67 (95% CI 1.09, 6.57) increased risk of ALL in children born by caesarean delivery, but the findings are difficult to interpret due to data exclusions (eg multiple pregnancies, delivery before 37 weeks, emergency deliveries) . Conversely, a nationwide record linkage study, using data from birth and cancer registries including 7 029 843 children from Denmark, Finland, and Sweden, found no association between childhood leukaemia and caesarean section, either elective or emergency (adjusted HR 1.02, 95% CI 0.92, 1.13) …”

“…In this context, it has been suggested that because children born by caesarean delivery may not be subject to the same hormonal and microbial challenges as those born vaginally, their immune development could be altered, which in turn could increase their risk of ALL. Although findings from the majority of studies examining the relationship with caesarean delivery have provided little support for this hypothesis, some investigators observed that children delivered by caesarean, especially if performed before the onset of labour, may be at increased ALL risk. A further case‐control study, finding no overall association with caesarean delivery, either before or during labour, reported an increased risk with prelabour caesarean among children diagnosed with ALL before three years of age; and a Californian birth record linkage study reported a 20% increased risk of ALL with caesarean delivery (pre‐ and post‐labour combined) in children aged 2‐4 years …”