Maternal and paternal risk factors for cryptorchidism and hypospadias: A case-control study in newborn boys

Little is known on environmental risk factors for cryptorchidism and hypospadias, which are
among the most frequent congenital abnormalities. The aim of our study was to identify risk factors
for cryptorchidism and hypospadias, with a focus on potential endocrine disruptors in
parental diet and occupation. In a case–control study nested within a cohort of 8,698 male births,
we compared 78 cryptorchidism cases and 56 hypospadias cases with 313 controls. The participation
rate was 85% for cases and 68% for controls. Through interviews, information was collected
on pregnancy aspects and personal characteristics, lifestyle, occupation, and dietary phytoestrogen
intake of both parents. Occupational exposure to potential endocrine disruptors was classified
based on self-reported exposure and ratings of occupational hygienists based on job descriptions.
Our findings indicate that paternal pesticide exposure was associated with cryptorchidism [odds
ratio (OR) = 3.8; 95% confidence interval (95% CI), 1.1–13.4]. Smoking of the father was associated
with hypospadias (OR = 3.8; 95% CI, 1.8–8.2). Maternal occupational, dietary, and lifestyle
exposures were not associated with either abnormality. Both abnormalities were associated with
suboptimal maternal health, a lower maternal education, and a Turkish origin of the parents.
Being small for gestational age was a risk factor for hypospadias, and preterm birth was a risk factor
for cryptorchidism. Because paternal pesticide exposure was significantly associated with cryptorchidism
and paternal smoking was associated with hypospadias in male offspring, paternal
exposure should be included in further studies on cryptorchidism and hypospadias risk factors.
Key words: children, cryptorchidism, endocrine disruptor, environment, epidemiology, hypospadias,
nutrition, occupational exposure, testis.