Risk of Cancer in Children Conceived by Assisted Reproductive Technology

Abstract

Background and objective: An increasing number of children are born after assisted reproductive technology (ART), and monitoring their long-term health effects is of interest. This study compares cancer risk in children conceived by ART to that in children conceived without.

Methods: The Medical Birth Registry of Norway contains individual information on all children born in Norway (including information of ART conceptions). All children born between 1984 and 2011 constituted the study cohort, and cancer data were obtained from the Cancer Registry of Norway. Follow-up started at date of birth and ended on the date of the first cancer diagnosis, death, emigration, or December 31, 2011. A Cox proportional hazards model was used to calculate hazard ratios (HR) and 95% confidence intervals (CI) of overall cancer risk between children conceived by ART and those not. Cancer risk was also assessed separately for all childhood cancer types.

Results: The study cohort comprised 1 628 658 children, of which 25 782 were conceived by ART. Of the total 4554 cancers, 51 occurred in ART-conceived children. Risk of overall cancer was not significantly elevated (HR 1.21; 95% CI 0.90-1.63). However, increased risk of leukemia was observed for children conceived by ART compared with those who were not (HR 1.67; 95% CI 1.02-2.73). Elevated risk of Hodgkin's lymphoma was also found for ART-conceived children (HR 3.63; 95% CI 1.12-11.72), although this was based on small numbers.

Conclusions: This population-based cohort study found elevated risks of leukemia and Hodgkin's lymphoma in children conceived by ART.

FIGURE 1

A directed acyclic graph showing confounding and mediating factors in the current study associated with ART and childhood cancer. Covariates in red indicate that they have been classified as confounding factors; covariates in blue have been classified as intermediate factors.

FIGURE 2

Description of the establishment of the study cohort. Children conceived by ART are those registered as conceived by ART in the MBRN; children not conceived by ART are those without a registered ART conception in the MBRN.

FIGURE 3

Characteristics of ART offspring compared with non-ART offspring in Norway, changes over 28 years (1984–2011). A, Number of children born after being conceived by ART, by method, each year in Norway, 1984–2011. B, Number of children born as being part of a multiple birth (percent of all pregnancies), by mode of conception in Norway, 1984–2011. C, Birth weight of children born in Norway 1984–2011, by mode of conception and birth year. D, Gestational age of children born in Norway, 1984–2011, by mode of conception and birth year. In panels C and D, the length of the colored intervals indicates the values that lie between the 25th and 75th percentiles. The length of the black lines indicates the range.