Cryptorchidism and hypospadias in a cohort of 934,538 Danish boys: the role of birth weight, gestational age, body dimensions, and fetal growth

Do ethnic patterns in cryptorchidism reflect those found in testicular cancer?

PURPOSE

There are established variations in testicular cancer incidence between ethnic groups within countries. It is currently unclear whether the occurrence of cryptorchidism-a known risk factor for testicular cancer-follows similar patterns. In New Zealand Māori have unusually high rates of testicular cancer compared to individuals of European ancestry. We hypothesized that ethnic trends in the incidence of cryptorchidism would reflect those for testicular cancer in this setting.

MATERIALS AND METHODS

We followed 318,441 eligible male neonates born in New Zealand between 2000 and 2010 for the incidence of orchiopexy confirmed cryptorchidism and the incidence of known risk factors for cryptorchidism (low birth weight, short gestation, small size for gestational age) using routine maternity, hospitalization and mortality records. Logistic regression was used to calculate odds ratios for the presence of known risk factors for cryptorchidism by ethnic group. Poisson regression was used to calculate relative risk of cryptorchidism by ethnicity, adjusted for risk factors.

RESULTS

Ethnic patterns of cryptorchidism incidence in New Zealand closely mirrored those previously observed for testicular cancer. Māori had higher rates of cryptorchidism than all other ethnic groups (adjusted RR 1.2 [95% CI 1.11-1.3]), with Pacific (0.89 [0.8-0.99]) and Asian groups (0.68 [0.59-0.79]) having the lowest rates (European/other, referent).

CONCLUSIONS

Since the principal risk factors for cryptorchidism are present in utero, the results of the current study strengthen the likelihood that the ethnic patterning of testicular cancer is at least partly due to prenatal risk factors.

The exposome--exciting opportunities for discoveries in reproductive and perinatal epidemiology

Understanding the mechanisms that underlie successful human reproduction and development is an ambitious goal, given the many unique methodological challenges surrounding such study. These challenges are well understood by reproductive and perinatal epidemiologists and include its conditional nature, unobservable yet informative outcomes such as conception, multi-scale missing data, correlated or non-independent outcomes, interval censoring and a hierarchical data structure. Novel methodologies for overcoming these challenges and for answering critical data gaps are needed if we are to better understand the inefficiency that currently characterises human reproduction with the goal of improving population health. The exposome is an emerging paradigm that offers promise for understanding the natural history of human reproduction and development, and its many associated impairments that develop later in child- or adulthood. This novel paradigm recognises the need to identify and measure the totality of environmental (non-genetic) exposures from preconception through sensitive windows, and to identify patterns associated with healthy and adverse outcomes. The exposome accommodates research focusing on unique subpopulations, such as couples undergoing assisted reproductive technologies, so that methodological limitations such as unobservable and conditional outcomes can be better addressed. Reproductive and perinatal epidemiology is uniquely suited for proof-of-concept exposome research, given the intricate relations between fecundity, gravid health and later onset disease and the narrow and interrelated sensitive windows that characterise the conditional nature of human reproduction and development. Bold new conceptual frameworks such as the exposome are needed for designing research that may lead to discovery and improve population health.

Does infertility treatment increase male reproductive tract disorder?

OBJECTIVE

To determine the association between assisted human reproduction and male reproductive disorders in infants conceived by this means.

MATERIALS AND METHODS

Between January 2008 and December 2011, 15,332 neonates were born in our hospital. We assessed the birth weight, gestational age, and other characteristics of the 7752 male infants and determined the association between methods of conception and male reproductive disorders in the infants. We also analyzed the influence of male factor on the occurrence of these disorders.

RESULTS

Ninety-nine newborns (1.3%) were diagnosed with cryptorchidism, 8 (0.1%) were diagnosed with hypospadias, and 4 (0.05%) were diagnosed with both. Cryptorchidism was more common in children conceived through in vitro fertilization (IVF) and IVF/intracytoplasmic sperm injection (IVF/ICSI; P <.05), and hypospadias was more common in children conceived through IVF/ICSI (P <.05). Children conceived through intrauterine insemination (IUI), IVF, and IVF/ICSI had higher rates of low birth weight and preterm birth. Logistic regression analysis showed that low birth weight and preterm birth were significantly associated with male reproductive disorders, whereas the method of conception was not. Male factor was not significantly associated with these disorders.

CONCLUSION

IVF and IVF/ICSI increase the risks of low birth weight and preterm birth, resulting in increased rates of hypospadias and cryptorchidism. Male factor was not associated with reproductive disorders in male infants.

Altered infant feeding patterns in boys with acquired nonsyndromic cryptorchidism

BACKGROUND

Genetic and environmental factors likely influence susceptibility to nonsyndromic cryptorchidism, a common disease presenting at birth or in later childhood. We compared cases and controls to define differential risk factors for congenital versus acquired cryptorchidism.

METHODS

We compared questionnaire and clinical data from cases of congenital cryptorchidism (n = 230), acquired cryptorchidism (n = 182) and hernia/hydrocele (n = 104) with a group of healthy male controls (n = 358). Potential predictor variables (p < 0.2 in univariable analysis) were included in stepwise multivariable logistic regression models.

RESULTS

Temporary (odds ratio [OR], 0.5; 95% confidence interval [CI], 0.4-0.8) or exclusive (OR, 0.6; 95% CI, 0.4-0.9) breastfeeding was reduced and soy formula feeding increased (OR, 1.8; 95% CI, 1.2-2.9) in acquired but not congenital or hernia/hydrocele groups. The highest risk estimates were observed for primary soy formula feeding with limited or no breastfeeding (OR 2.5; 95% CI, 1.4-4.3; adjusted OR, 2.7; 95% CI, 1.4-5.4) in the acquired group. Primary feeding risk estimates were equivalent or strengthened when multivariable models were limited to age greater than 2 years, full-term or not small for gestational age, or Caucasian subjects. Pregnancy complications and increased maternal exposure to cosmetic or household chemicals were not consistently associated with either form of cryptorchidism in these models.

CONCLUSIONS

Our data support reduced breastfeeding and soy formula feeding as potential risk factors for acquired cryptorchidism. Although additional studies are needed, hormonally active components of breast milk and soy formula could influence the establishment of normal testis position in the first months of life, leading to apparent ascent of testes in childhood. Birth Defects Research (Part A), 2012.

Accuracy of cryptorchidism diagnoses and corrective surgical treatment registration in the Danish National Patient Registry

PURPOSE

In recent years several Danish studies of the etiology, time trends and long-term health consequences of cryptorchidism have relied on diagnoses and surgical treatments registered in the National Patient Registry. We evaluated the diagnostic accuracy of these registry data.

MATERIALS AND METHODS

According to the Danish National Patient Registry, 16,168 males were diagnosed with cryptorchidism and 9,244 surgical treatments for cryptorchidism were performed between January 1, 1995 and October 10, 2009. We randomly selected 500 diagnosed cases, of which 284 had been managed surgically. We requested the medical records from the departments making the diagnoses and performing the surgery.

RESULTS

We successfully retrieved medical records for 452 diagnosed cases (90%) and 249 operations (88%). Overall positive predictive value of a registry diagnosis of cryptorchidism was 80% (95% CI 77-84) using the testicular position described by the physician performing the clinical examination as the gold standard. Similarly the positive predictive value of the surgical treatment registration was 99% (95% CI 98-100) using the type of procedure performed.

CONCLUSIONS

The data on cryptorchidism in the Danish National Patient Registry are quite accurate. In etiological research the limited misclassification will in most cases only slightly attenuate estimates of the true relative association. Thus, the registry has the potential to serve as a valuable research tool, although caution should be exercised when studying time trends or geographical differences.