Association between exposure during pregnancy and the risk of developing solid tumors in second children: Results from a Chinese matched case-control study.

Background: Even though many studies have proven the risk factors for cancer in children, studies focusing exclusively on second children are absent. This study is designed to examine the association between maternal exposure during pregnancy and the risk of developing solid tumors (STs) in second children.

Methods: This retrospective matched case-control study included 80 s children with STs and 160 s children without STs matched in terms of birth weight, gestational age, pregnancy body mass index (BMI), and residence from a medical center. Exposure during pregnancy and birth characteristics of these children were investigated through structured questionnaires.

Results: A univariate analysis suggested that birth spacing (OR, 12.70; CI, 4.44-36.34), maternal smoking (OR, 6.00; CI, 1.62-22.16), paternal smoking (OR, 2.20; CI, 1.23-3.93), and common cold (OR,1.94; CI, 1.02-3.69) were associated with an increased risk of second children STs. A multivariate analysis demonstrated that birth spacing (OR, 12.45; CI, 4.00-38.78) and paternal smoking (OR, 2.04; CI, 1.04-3.99) were the main risk factors for STs in second-born children.

Conclusion: Long birth spacing (>10 years) and paternal smoking could significantly increase the risk of developing STs in second-born children. Despite the fact that the effects of maternal smoking and the common cold were not significant, it is still recommended to quit smoking, take necessary self-protective measures to reduce the risk of infection.