Difference in prevalence of congenital cryptorchidism in infants between two Nordic countries

Rates of orchiopexies in Sweden: 1977-1991

Cryptorchidism is a known risk factor for testicular cancer and the secular increase in testicular cancer incidence might have been paralleled by a similar increase in cryptorchidism. Data on trends in prevalence of cryptorchidism are however conflicting and decreases have recently been reported. To analyse Swedish trends in rates of orchiopexy, we used the Swedish Hospital Discharge Register to identify all cases of orchiopexy carried out for cryptorchidism between 1977 and 1991, that is, before the era of outpatient orchiopexies in Sweden. Observed trends were analysed in 5-year age groups. The estimated average annual per cent changes (EAPCs) and the years in which the EAPC significantly changed were estimated using Joinpoint Regression. Finally, we estimated the cumulative incidence of orchiopexy by birth cohort. Among boys aged less than 10, the orchiopexy rate started to decrease in the early 1980s. EAPCs were -2.88 (95% confidence interval (CI): -5.48, -0.21) among boys aged 5-9 and -6.63 among those aged 0-4 (95% CI: -8.84, -4.37). Among subjects aged at least 10, the rate decreased over the whole study period. Although the use of orchiopexy rates to measure prevalence of cryptorchidism has limitations, our findings may suggest that cryptorchidism prevalence decreased in Sweden starting from the early 1980s.

Testicular dysgenesis syndrome and Leydig cell function

Fertility among human beings appear to be on the decline in many Western countries, and part of the explanation may be decreasing male fecundity. A hypothesis has been put forward that decreasing semen quality may be associated with a testicular dysgenesis syndrome (TDS), a spectrum of disorders originating in early foetal life. TDS comprises various aspects of impaired gonadal development and function, including testicular cancer. A growing body of evidence, including animal models and research in human beings, points to lifestyle factors and endocrine disrupters as risk factors for TDS. We present our view of the emerging role of Leydig cell dysfunction with subsequent decreased testosterone levels in the pathogenesis of TDS.

Testicular dysgenesis syndrome and the estrogen hypothesis: a quantitative meta-analysis

BACKGROUND

Male reproductive tract abnormalities such as hypospadias and cryptorchidism, and testicular cancer have been proposed to comprise a common syndrome together with impaired spermatogenesis with a common etiology resulting from the disruption of gonadal development during fetal life, the testicular dysgenesis syndrome (TDS). The hypothesis that in utero exposure to estrogenic agents could induce these disorders was first proposed in 1993. The only quantitative summary estimate of the association between prenatal exposure to estrogenic agents and testicular cancer was published over 10 years ago, and other systematic reviews of the association between estrogenic compounds, other than the potent pharmaceutical estrogen diethylstilbestrol (DES), and TDS end points have remained inconclusive.

OBJECTIVES

We conducted a quantitative meta-analysis of the association between the end points related to TDS and prenatal exposure to estrogenic agents. Inclusion in this analysis was based on mechanistic criteria, and the plausibility of an estrogen receptor (ER)-alpha-mediated mode of action was specifically explored.

RESULTS

We included in this meta-analysis eight studies investigating the etiology of hypospadias and/or cryptorchidism that had not been identified in previous systematic reviews. Four additional studies of pharmaceutical estrogens yielded a statistically significant updated summary estimate for testicular cancer.

CONCLUSIONS

The doubling of the risk ratios for all three end points investigated after DES exposure is consistent with a shared etiology and the TDS hypothesis but does not constitute evidence of an estrogenic mode of action. Results of the subset analyses point to the existence of unidentified sources of heterogeneity between studies or within the study population.

Influence of endocrine disruptors on human male fertility

It has been suggested that during the past five decades human sperm counts have declined and the incidence of testicular cancer, hypospadias and cryptorchidism has increased. Furthermore, geographical differences, with respect to these markers of male reproductive function, have been reported. According to a recent hypothesis, all these abnormalities of the male genital system do have a common cause, namely exposure to endocrine disruptors affecting the male in early fetal life. Reduced sperm production as well as congenital abnormalities of male genitalia can be evoked in laboratory animals by exposing them to chemicals with endocrine-disrupting effect, and in humans similar effects have been seen following accidental exposures to very high concentrations of these environmental toxicants. However, the evidence for association between levels of exposure found in the general population and serious adverse effects on male reproduction, including fertility, is still lacking. A recent European Union-supported study, on the effect of persistent organohalogen pollutants on human reproduction, failed to show any correlation between post-natal exposure levels and fertility. Future studies will reveal whether prenatal exposure does more strongly affect male fertility and whether genetic predisposition regulates the susceptibility of an individual to the adverse effects of endocrine disruptors.

Hormonal and genetic control of testicular descent

Cryptorchidism has the potential to affect the health of the human male. Although it is often considered a mild malformation, it represents the best-characterized risk factor for reduced fertility and testicular cancer. The aetiology of cryptorchidism remains, for the most part, unknown and cryptorchidism itself might be considered a complex disease. This reflects the intricate mechanisms regulating testicular development and descent from intra-abdominal location into the bottom of the scrotum, involving different anatomical and hormonal factors. Major actors of testicular descent are the Leydig cell-derived hormones testosterone and insulin-like factor 3, even if other factors may play a role. Although considerable evidence exists in animals to support a genetic cause, the genetic contribution to human cryptorchidism is only recently being elucidated. Environmental factors might also contribute to the aetiology of cryptorchidism and its increased incidence in recent years. Mutations in the gene for insulin-like factor 3 and its receptor and in the androgen receptor gene explain a minority of cases of cryptorchidism, but research on genetic polymorphisms that may also influence susceptibility to endocrine disruptors is shedding light on this field.

Adverse trends in male reproductive health: we may have reached a crucial 'tipping point'

Healthy men produce an enormous number of sperms, far more than necessary for conception. However, several studies suggest that semen samples where the concentration of sperms is below 40 mill/mL may be associated with longer time to pregnancy or even subfertility, and specimens where the concentration of sperms is below 15 mill/mL may carry a high risk of infertility. Historic data from the 1940s show that the bulk of young men at that time had sperm counts far above 40 mill/mL with averages higher than 100 mill/mL. However, recent surveillance studies of young men from the general populations of young men in Northern Europe show that semen quality is much poorer. In Denmark approximately 40 percent of the men have now sperm counts below 40 mill/mL. A simulation assuming that average sperm count had declined from 100 mill/mL in ‘old times’ to a current level close to 40 mill/mL indicated that the first decline in average sperm number of 20–40 mill/mL might not have had much effect on pregnancy rates, as the majority of men would still have had counts far above the threshold value. However, due to the assumed decline in semen quality, the sperm counts of the majority of 20 year old European men are now so low that we may be close to the crucial tipping point of 40 mill/mL spermatozoa. Consequently, we must face the possibility of more infertile couples and lower fertility rates in the future.

Semen quality of Asian men

After the controversial report by Carlsen et al. in 1992 showing a possible decline in human semen quality over the past 50 years, many laboratories investigated their own records of semen findings that had been kept for the past decades, and a significant decrease in sperm quality was reported from some laboratories, but not others. At the beginning of the 21st century, a definitive interpretation of this issue has not yet been offered; however, it seems plausible that there are large regional differences in semen quality. Decreases in semen quality have been reported from various regions around the world, and a concurrent rise in the incidence of other reproductive problems, such as testicular cancer and genital abnormalities, has been observed in many regions. However, most of the reports showing regional differences were from Western or Western-derived countries, despite the fact that Asia is the region with the highest population on earth. Recently we undertook a cross-sectional study on fertile men in Japan to describe the current status of semen quality of Japanese men. We took confounders into consideration to allow a comparison with a previous European study. Japanese fertile men proved to have a semen quality at the level of Danish men, who were reported to have the lowest level among the men examined in the European study. This low level of sperm concentration in fertile Japanese men may result from differences in lifestyle or other environmental factors, but we cannot rule out the possibility of ethnic differences caused by different genetic variation or combination. To address this issue we need more information on the reproductive function in Asian men, who have been reported to have certain differences in reproductive characteristics from Caucasian men. This article is an attempt to review our present knowledge concerning the current status of semen quality in healthy Asian men on the basis of the limited publications from Asia. (Reprod Med Biol 2007; 6: 185-193).

Human exposure to endocrine-disrupting chemicals and prenatal risk factors for cryptorchidism and hypospadias: a nested case-control study

BACKGROUND

Exposure to xenoestrogens during pregnancy may disturb the development and function of male sexual organs.

OBJECTIVE

In this study we aimed to determine whether the combined effect of environmental estrogens measured as total effective xenoestrogen burden (TEXB) is a risk factor for male urogenital malformations.

METHODS

In a case-control study, nested in a mother-child cohort (n = 702) established at Granada University Hospital, we compared 50 newborns with diagnosis of cryptorchidism and/or hypospadias with 114 boys without malformations matched by gestational age, date of birth, and parity. Controls did not differ from the total cohort in confounding variables. TEXB and levels of 16 organochlorine pesticides were measured in placenta tissues. Characteristics of parents, pregnancy, and birth were gathered by questionnaire. We used conditional and unconditional regression models to estimate odds ratios (ORs) and 95% confidence intervals (CIs).

RESULTS

TEXB from organohalogenated compounds was detectable in 72% and 54% of case and control placentas, respectively. Compared with controls, cases had an OR for detectable versus non-detectable TEXB of 2.82 (95% CI, 1.10-7.24). More pesticides were detected in cases than in controls (9.34 +/- 3.19 vs. 6.97 +/- 3.93). ORs for cases with detectable levels of pesticides, after adjusting for potential confounders in the conditional regression analysis, were o,p'-DDT (OR = 2.25; 95% CI, 1.03-4.89), p,p'-DDT (OR = 2.63; 95% CI, 1.21-5.72), lindane (OR = 3.38; 95% CI, 1.36-8.38), mirex (OR = 2.85; 95% CI, 1.22-6.66), and endosulfan alpha (OR = 2.19; 95% CI, 0.99-4.82). Engagement of mothers in agriculture (OR = 3.47; 95% CI, 1.33-9.03), fathers' occupational exposure to xenoestrogens (OR = 2.98; 95% CI, 1.11-8.01), and history of previous stillbirths (OR = 4.20; 95% CI, 1.11-16.66) were also associated with risk of malformations.

CONCLUSIONS

We found an increased risk for male urogenital malformations related to the combined effect of environmental estrogens in placenta.

The true incidence of cryptorchidism in Denmark

PURPOSE

Considerable controversy exists regarding the recently published high prevalence of cryptorchidism and the actual orchiopexy rate in Denmark. Therefore, we carried out another prevalence study.

MATERIALS AND METHODS

The study population included 1,094 consecutive males delivered alive at Glostrup University Hospital during 2002, with a 4-year review of patient data and telephone contact with primary physicians.

RESULTS

At birth the overall frequency of cryptorchidism was 2.4% (26 of 1,088 cases, 23% bilateral). The frequency of cryptorchidism in singletons was 2.4% (24 of 1,012 patients). The frequency of cryptorchidism in patients with a birth weight of 2,500 gm or more was 2.1%, compared to 8.2% in those with a birth weight of less than 2,500 gm (chi-square p <0.05). The frequency of cryptorchidism in twins was 2.6% (2 of 76). The frequency of birth weight below 2,500 gm was 51% (39 of 76) in twins and 4.9% (50 of 1,012) in singletons (chi-square p <0.00005). The weight of the placenta was higher in twins (median 1,000 gm) than in singletons (650 gm). At age 4 years 1.6% of the boys had undergone or were waiting to undergo surgery for cryptorchidism, and 0.6% had a diagnosis of retractile testes.

CONCLUSIONS

In a small cohort of newborns the incidence of cryptorchidism in Denmark has not changed, and is similar to previous reports from the 1950s. The risk is higher in low birth weight singleton neonates but does not appear to be higher in twins, despite lower birth weight and prematurity.

Maternal pregnancy serum level of heptachlor epoxide, hexachlorobenzene, and beta-hexachlorocyclohexane and risk of cryptorchidism in offspring

Prenatal exposure to environmental endocrine disrupters has been postulated to cause adverse effects on male reproductive health. Exposure to organochlorine pesticides with anti-androgenic and estrogenic potency has been shown to interfere with the sex-hormone-dependent process of testicular descent in animal models. We examined the relation between serum levels of the pesticides heptachlor epoxide (HCE), hexachlorobenzene (HCB), and beta-hexachlorocyclohexane (beta-HCCH) in pregnant women, and the occurrence of cryptorchidism in their sons. These three pesticides were previously suggested as risk factors for cryptorchidism. In a nested case-control design, we compared serum levels between mothers of cases (n = 219) and controls (n = 564), selected from the Collaborative Perinatal Project, a US birth cohort study of pregnancies in 1959-1966. The offspring of mothers with HCE levels above the 90th percentile compared to those below the 10th percentile had an adjusted odds ratio of cryptorchidism of 1.2 (95% confidence interval 0.6-2.6); for beta-HCCH the odds ratio was 1.6 (0.7-3.6). For HCB the adjusted odds ratio was near one. These results provide little support for an association of cryptorchidism with exposure to low levels of HCE or HCB. For beta-HCCH the findings were somewhat suggestive of an association but were inconclusive.

Estrogen receptor alpha is a major contributor to estrogen-mediated fetal testis dysgenesis and cryptorchidism

Failure of the testes to descend into the scrotum (cryptorchidism) is one of the most common birth defects in humans. In utero exposure to estrogens, such as 17beta-estradiol (E2) or the synthetic estrogen diethylstilbestrol (DES), down-regulates insulin-like 3 (Insl3) expression in embryonic Leydig cells, which in turn results in cryptorchidism in mice. To identify the molecular mechanism whereby xenoestrogens block Insl3 gene transcription, we performed a microarray analysis of wild-type or estrogen receptor (ER) alpha-mutant testes exposed in utero to pharmacological doses of E2 or DES. Six and 31 genes were respectively down-regulated and up-regulated by estrogen exposure (> or =4-fold). All six genes down-regulated by estrogen exposure, including Insl3 and the steroidogenic genes steroidogenic acute regulatory protein and cytochrome P450 17alpha-hydroxylase/17,20-lyase, were done so by an ERalpha-dependent mechanism. In contrast, up-regulation was mediated either by ERalpha for 12 genes or by an independent mechanism for the 19 remaining genes. Finally, we show that Insl3 gene expression and testicular descent were not affected by in utero exposure to E2 or DES in ERalpha mutant mice, whereas absence of ERbeta did not influence the effect of these estrogens. Collectively, these data demonstrate that xenoestrogens inhibit the endocrine functions of fetal Leydig cells through an ERalpha-dependent mechanism.

Testicular cancer trends as 'whistle blowers' of testicular developmental problems in populations

Recently a worldwide rise in the incidence of testicular germ cell cancer (TGCC) has been repeatedly reported. The changing disease pattern may signal that other testicular problems may also be increasing. We have reviewed recent research progress, in particular evidence gathered in the Nordic countries, which shows strong associations between testicular cancer, undescended testis, hypospadias, poor testicular development and function, and male infertility. These studies have led us to suggest the existence of a testicular dysgenesis syndrome (TDS), of which TGCC, undescended testis, hypospadias/disorders of sex differentiation and male fertility problems may be symptoms with varying penetration. In spite of their fetal origin, most of the TDS symptoms, including TGCC and poor semen quality, can only be diagnosed in adulthood. Data from a Danish-Finnish research collaboration strongly suggest that trends in TGCC rates of a population may be 'whistle blowers' of other reproductive health problems. As cancer registries are often of excellent quality - in contrast to registries for congenital abnormalities - health authorities should consider an increase in TGCC as a warning that other reproductive health problems may also be rising.

Flame retardants in placenta and breast milk and cryptorchidism in newborn boys

BACKGROUND

Polybrominated diphenyl ethers (PBDEs) are widely used in Western countries.

OBJECTIVES

Because the prevalence of cryptorchidism appears to be increasing, we investigated whether exposure to PBDEs was associated with testicular maldescent.

METHODS

In a prospective Danish-Finnish study, 1997-2001, all boys were examined for cryptorchidism. We analyzed whole placentas (for 95 cryptorchid/185 healthy boys) and individual breast milk samples (62/68) for 14 PBDEs and infant serum samples for gonadotropins, sex-hormone binding globulin, testosterone, and inhibin B.

RESULTS

In 86 placenta-milk pairs, placenta PBDE concentrations in fat were lower than in breast milk, and a larger number of congeners were nondetectable. There was no significant difference between boys with and without cryptorchidism for individual congeners, the sum of 5 most prevalent, or all 14 congeners. The concentration of PBDEs in breast milk was significantly higher in boys with cryptorchidism than in controls (sum of BDEs 47, 153, 99, 100, 28, 66, and 154: median, 4.16 vs. 3.16 ng/g fat; p < 0.007). There was a positive correlation between the sum of PBDEs and serum luteinizing hormone (p < 0.033). The sum of PBDEs in breast milk did not differ between Denmark and Finland (median, 3.52 vs. 3.44 ng/g fat), but significant differences in some individual congeners were found.

CONCLUSIONS

Two different proxies were used for prenatal PBDE exposure, and levels in breast milk, but not in placenta, showed an association with congenital cryptorchidism. Other environmental factors may contribute to cryptorchidism. Our observations are of concern because human exposure to PBDEs is high in some geographic areas.

Insulin-like factor 3 levels in cord blood and serum from children: effects of age, postnatal hypothalamic-pituitary-gonadal axis activation, and cryptorchidism

CONTEXT

The Leydig cell hormone insulin-like factor 3 (INSL3) is important for testicular descent. Currently INSL3 levels in cord blood, in serum throughout childhood, and in relation to congenital cryptorchidism are unknown.

OBJECTIVE

The objective of the study was to characterize INSL3 levels in cord blood during the postnatal activation of the hypothalamic-pituitary-gonadal axis and in later childhood in normal boys and girls and cryptorchid boys.

DESIGN AND PARTICIPANTS

Serum from 267 3-month-old boys of a prospective study with standardized cryptorchidism classification was analyzed for INSL3 (of these, 99 also had cord blood samples). Testicular position was known in 151 controls and 54 transiently cryptorchid and 62 persistently cryptorchid subjects. Eight infant girls, 26 boys (4.1-10.1 yr), and 13 girls (3.7-8.7 yr) were also included.

OUTCOME MEASURE

INSL3, age, testicular position, LH, and testosterone were measured.

RESULTS

INSL3 levels were significantly higher (P < 0.001) in cord blood and 3-month-old boys as compared with older prepubertal boys. At 3 months of age, INSL3 correlated significantly with LH in healthy boys. Cord blood INSL3 was significantly reduced in persistently cryptorchid boys (P = 0.001), and 3-month-old persistently cryptorchid boys had a significantly increased LH to INSL3 ratio (P = 0.014). INSL3 was unmeasurable in girls at all ages.

CONCLUSIONS

In boys, early postnatal INSL3 is markedly higher as compared with later childhood, presumably because it is stimulated by the transient postnatal LH peak. INSL3 was unmeasurable in girls at all ages. Reduced cord blood INSL3 and an increased LH to INSL3 ratio at 3 months of age in persistently cryptorchid boys suggest impaired Leydig cell function in cryptorchid boys already in the perinatal period.

Environment, testicular dysgenesis and carcinoma in situ testis

The testicular dysgenesis syndrome (TDS) hypothesis proposes that a proportion of the male reproductive disorders-cryptorchidism, hypospadias, infertility and testicular cancer-may be symptoms of one underlying developmental disease, TDS, which is most likely a result of disturbed gonadal development in the embryo. TDS may be caused by genetic factors, environmental/life-style factors, or a combination of both. Some rare disorders of sex development of genetic origin are among the best-known examples of severe TDS. Among the environmental and life-style factors that are suspected to influence the hormonal milieu of the developing gonad are the endocrine disrupters. A prenatal exposure to commonly used chemicals, e.g. phthalates, may result in a TDS-like phenotype in rats. Currently, this animal model is the best model for TDS. In humans the situation is much more complex, and TDS exists in a wide range of phenotypes: from the mildest and most common form, in which impaired spermatogenesis is the only symptom, to the most severe cases, in which the patient may develop testicular cancer. It is of great importance that clinicians in different specialties treating patients with TDS are aware of the association between the different symptoms.

Reduced serum testosterone levels in infant boys conceived by intracytoplasmic sperm injection

CONTEXT

Concern has been raised for the health of the offspring conceived by assisted reproduction technologies. Basal reproductive hormones around 3 months of age reflect the pituitary-testicular axis, which is transiently active at this age.

OBJECTIVES

We tested the hypothesis that transmission of impaired testicular function from father to son could be detected at 3 months of age in boys conceived by intracytoplasmic sperm injection (ICSI), which is predominantly used in the management of male infertility.

DESIGN

We conducted a longitudinal prospective cohort study, including 125 boys conceived by ICSI, 124 boys conceived by in vitro fertilization (IVF), and 933 naturally conceived (NC) boys.

INTERVENTION

Anthropometrical measurements were performed at birth and at 3 months of age; 58, 67, and 64% of ICSI, IVF, and NC boys, respectively, had a blood sample taken at 3 months.

MAIN OUTCOME MEASURES

We measured serum levels of LH, FSH, SHBG, inhibin B, testosterone, as well as penile length.

RESULTS

Serum testosterone levels were significantly lower in boys conceived by ICSI (2.4 nmol/liter; 0.2-4.9 nmol/liter) (median; 2.5th-97.5th percentiles) compared with NC boys (3.3 nmol/liter; 0.6-7.6 nmol/liter; P < 0.001), and the LH to testosterone ratio was increased (0.8; 0.2-7.9 vs. 0.5; 0.2-2.3, respectively; P = 0.001). Boys conceived by IVF because of female infertility factors had a normal serum testosterone and LH to testosterone ratio compared with controls. Adjusted analyses for confounders did not alter the results.

CONCLUSIONS

Our results point toward a subtle impairment of Leydig cell function in boys conceived by ICSI, possibly inherited from their fathers. The clinical significance of our findings is uncertain. However, our findings should raise concern because ICSI is increasingly used to overcome male infertility.

Metabolism of phthalates in humans

Phthalates are synthetic compounds widely used as plasticisers, solvents and additives in many consumer products. Several animal studies have shown that some phthalates possess endocrine disrupting effects. Some of the effects of phthalates seen in rats are due to testosterone lowering effects on the foetal testis and they are similar to those seen in humans with testicular dysgenesis syndrome. Therefore, exposure of the human foetus and infants to phthalates via maternal exposure is a matter of concern. The metabolic pathways of phthalate metabolites excreted in human urine are partly known for some phthalates, but our knowledge about metabolic distribution in the body and other biological fluids, including breast milk, is limited. Compared to urine, human breast milk contains relatively more of the hydrophobic phthalates, such as di-n-butyl phthalate and the longer-branched, di(2-ethylhexyl) phthalate (DEHP) and di-iso-nonyl phthalate (DiNP); and their monoester metabolites. Urine, however, contains relatively more of the secondary metabolites of DEHP and DiNP, as well as the monoester phthalates of the more short-branched phthalates. This differential distribution is of special concern as, in particular, the hydrophobic phthalates and their metabolites are shown to have adverse effects following in utero and lactational exposures in animal studies.

Reduction in the number of orchidopexies for cryptorchidism after recognition of acquired undescended testis and implementation of expectative policy

BACKGROUND

Since the mid-1990s, acquired undescended testis has gradually been recognised as a separate entity for which the efficacy of prepubertal surgery has not been univocally been demonstrated. Therefore, in our hospital, orchidopexy was no longer routinely performed for acquired undescended testis.

AIM

To investigate the effect of expectative policy in our hospital on the number of orchidopexies.

METHODS

Two 5-year periods were compared. Period A (1991-1995), in which undescended testis was treated surgically, and period B (2000-2004), in which prepubertal orchidopexy in our hospital was no longer performed for acquired undescended testis. In addition, a comparison was made between the percentage reduction in hospital and national figures.

RESULTS

In period B, the number of orchidopexies in our hospital was reduced by 61.8% (from 387 to 148), mainly in the age group >6 years. Nationally, during the same period, the number of orchidopexies decreased only by 2.4% (from 18 024 to 17 591).

CONCLUSION

The results of this study confirm that recognition of acquired undescended testis is crucial for reducing the high number of (late) orchidopexies.

The frequency of undescended testis from birth to adulthood: a review

We performed a systematic review and critique of the literature on the frequency of undescended testis (UDT) among boys from birth to adolescence. Special attention was given to whether previous testicular position was taken into account to distinguish between congenital and acquired UDT. We searched Medline, Embase, Cinahl and the Cochrane Library. Any study reporting on the frequency of UDT was included. Study population age, number of boys studied, period of examination, primary examiner, area of study, study design, ethnicity, definitions used and previous testicular position were analysed. A total of 46 studies met the inclusion criteria. Twenty-three of the 46 (50%) studies involved newborns. Definitions were described in half of the studies; however, the definitions used were heterogeneous. Previous testis position was described in 11% (5/46) of the studies. At birth, in term and/or birth weight >2.5 kg infants, the UDT rate ranged from 1.0 to 4.6%, and in premature and/or birth weight <2.5 kg infants from 1.1 to 45.3%. At the age of 1 year UDT in term and/or birth weight >2.5 kg infants was seen in 1.0-1.5%, at 6 years in 0.0-2.6%, at 11 years in 0.0-6.6% and at 15 years in 1.6-2.2% of boys. The frequency of UDT shows variable figures in the literature. The actual frequency of acquired UDT essentially remains unclear because of the shortage of studies performed at an older age, and of studies reporting on previous testicular position.

Novel Mutations Involving the INSL3 Gene Associated With Cryptorchidism

PURPOSE

Cryptorchidism affects 1% to 9% of full-term male neonates. Hypospadias is the second most frequent congenital anomaly seen in newborn males. These pathological conditions are part of the testicular dysgenesis syndrome. Insulin-like factor 3 and LGR8 (leucine-rich repeat-containing G protein-coupled receptor 8), acting as a hormone and a receptor, respectively, are involved in control of the first phase of testicular descent via gubernacular development.

MATERIALS AND METHODS

The study group consisted of 184 patients, of whom 52 presented with unilateral cryptorchidism, 37 presented with bilateral cryptorchidism, 19 presented with cryptorchidism and hypospadias, 1 presented with bilateral cryptorchidism and micropenis, and 75 presented with isolated hypospadias. A control panel consisted of 270 controls, including 127 fertile, and 143 fertile noncryptorchid males. Insulin-like factor 3 mutations were analyzed by direct sequencing and restriction enzyme digestion. We analyzed the ability of the mutant insulin-like factor 3 peptides identified in this study to activate LGR8 receptor in an ex vivo assays.

RESULTS

We identified 3 novel insulin-like factor 3 variants, including C-19G, V18M and R105H, in 3 of the 109 patients (2.75%) but in none of the 270 controls. The V18M mutation in the insulin-like factor 3 signal peptide had a significant deleterious effect in activating LGR8 receptor in ex vivo studies (p<0.05). To our knowledge we report the first variant in the promoter region of the insulin-like factor 3 gene in a patient with cryptorchidism in association with micropenis.

CONCLUSIONS

Mutations involving the insulin-like factor 3 gene may contribute to other anomalies of male genital development, such as micropenis.

Development and descent of the testis in relation to cryptorchidism

The testis descends in two phases. Animal studies suggest, that the transabdominal descent of the testis depends on the insulin-like hormone 3 (INSL3). Androgens are important in the inguinoscrotal testicular descent in animals and humans. In general, the cause of cryptorchidism is unknown and the aetiology is possibly multifactorial. Histological changes in cryptorchid testes demonstrate disturbed development.

CONCLUSION

Since testicular descent is regulated by testis-derived hormones, cryptorchidism may reflect a functional defect of the testis.

Luteinizing hormone in testicular descent

A proper hypothalamus-pituitary-testis axis with normal androgen synthesis and action is a prerequisite for normal testicular descent. Various defects in this axis may result in cryptorchidism but endocrine abnormalities are rarely detected. Androgens regulate testicular descent but androgen action alone is not sufficient for normal testicular descent. The regulation of androgen production is influenced both by placental human chorionic gonadotropin (hCG) and pituitary luteinizing hormone (LH). There is evidence that the longer pregnancy continues, the more important role pituitary LH may have. Insulin-like hormone-3 (INSL3) is suggested to be the main regulator of gubernacular development and therefore an apparent regulator of testicular descent. INSL3 production is also related to LH, and reduced INSL3 action is a possible cause for cryptorchidism. Cryptorchid boys have normal testosterone levels with slightly but significantly elevated LH levels as compared to healthy boys. This high gonadotropin drive may compensate for mild Leydig cell dysfunction in cryptorchidism.

Small for gestational age: short stature and beyond

Depending on the definitions used, up to 10% of all live-born neonates are small for gestational age (SGA). Although the vast majority of these children show catch-up growth by 2 yr of age, one in 10 does not. It is increasingly recognized that those who are born SGA are at risk of developing metabolic disease later in life. Reduced fetal growth has been shown to be associated with an increased risk of insulin resistance, obesity, cardiovascular disease, and type 2 diabetes mellitus. The majority of pathology is seen in adults who show spontaneous catch-up growth as children. There is evidence to suggest that some of the metabolic consequences of intrauterine growth retardation in children born SGA can be mitigated by ensuring early appropriate catch-up growth, while avoiding excessive weight gain. Implicitly, this argument questions current infant formula feeding practices. The risk is less clear for individuals who do not show catch-up growth and who are treated with GH for short stature. Recent data, however, suggest that long-term treatment with GH does not increase the risk of type 2 diabetes mellitus and the metabolic syndrome in young adults born SGA.

Cryptorchidism according to maternal gestational smoking

BACKGROUND

It has been suggested that maternal smoking during pregnancy is a risk factor for low sperm counts and testicular cancer in the offspring. Cryptorchidism is associated with both of these disorders and might share causal mechanisms.

METHODS

We used prospective information on prenatal exposures and obstetric information on the birth of 5716 boys, collected from 1984 to 1987. During the 16-19 years of follow-up, 270 cases of cryptorchidism were diagnosed, and 185 of these boys underwent orchiopexy.

RESULTS

Compared with nonsmokers, the adjusted risk ratio for being diagnosed with cryptorchidism was 1.1 (95% confidence interval = 0.8-1.6) if the mothers smoked 10-19 cigarettes/day and 2.3 (1.1-5.0) if they smoked > or = 20 cigarettes/day. The risk ratios for orchiopexy were 1.4 (0.9-2.1) and 1.8 (0.6-5.0), respectively.

CONCLUSION

An excess risk of cryptorchidism was observed among sons of mothers who smoked 10 cigarettes or more per day during pregnancy. In recognition of the limited power of this study, the findings should be replicated in larger cohorts.

Cryptorchidism and maternal alcohol consumption during pregnancy

BACKGROUND

Prenatal exposure to alcohol can adversely affect the fetus. We investigated the association between maternal alcohol consumption during pregnancy and cryptorchidism (undescended testis) among newborn boys.

METHODS

We examined 2,496 boys in a prospective Danish-Finnish birth cohort study for cryptorchidism at birth (cryptorchid/healthy: 128/2,368) and at 3 months of age (33/2,215). Quantitative information on alcohol consumption (average weekly consumption of wine, beer, and spirits and number of binge episodes), smoking, and caffeine intake was obtained by questionnaire and/or interview once during the third trimester of pregnancy, before the outcome of the pregnancy was known. For a subgroup (n = 465), information on alcohol consumption was obtained twice during pregnancy by interviews.

RESULTS

We investigated maternal alcohol consumption both as a continuous variable and categorized. The odds for cryptorchidism increased with increasing weekly alcohol consumption. After adjustment for confounders (country, smoking, caffeine intake, binge episodes, social class, maternal age, parity, maturity, and birth weight) the odds remained significant for women with a weekly consumption of five or more alcoholic drinks (odds ratio = 3.10; 95% confidence interval, 1.05-9.10).

CONCLUSIONS

Regular alcohol intake during pregnancy appears to increase the risk of congenital cryptorchidism in boys. The mechanisms for this association are unknown. Counseling of pregnant women with regard to alcohol consumption should also consider this new finding.

High prevalence of testicular cancer in azoospermic men without spermatogenesis

BACKGROUND

An increased risk of testicular cancer in men with infertility and poor semen quality has been reported. Our aim was to investigate the prevalence of testicular nodules and cancer in azoospermic subjects with different spermatogenetic patterns.

METHODS

A total of 1443 consecutive infertile men were investigated, out of which 145 (10.0%) were found to be azoospermic. By using clinical examination and testicular ultrasound, 11 out of the 145 patients showed testicular nodules (2.8-26 mm). To obtain spermatozoa for assisted reproduction, 97 subjects required testicular sperm extraction (TESE) and biopsy, including the 11 patients with nodules. They were divided into two groups according to biopsy results: Group A (n = 38) with complete Sertoli cell-only syndrome (SCOS) and Group B (n = 59) with varying spermatogenetic patterns. Ten nodules were found in Group A and one in Group B.

RESULTS

In azoospermic men, the overall prevalence of nodules was 7.5%. In complete SCOS, the prevalence of nodules and cancer was 10/38 (26.3%) and 4/38 (10.5%), respectively. Amongst the cancers, one embryonal carcinoma, one seminoma and two in-situ carcinomas were found.

CONCLUSION

The prevalence of testicular nodules and cancer in azoospermic men with complete SCOS is very high. In these subjects, the role of clinical evaluation, ultrasound and biopsy should be emphasized.

Prevalence of acquired undescended testis in 6-year, 9-year and 13-year-old Dutch schoolboys

OBJECTIVE

To investigate the prevalence of acquired undescended testis (UDT) in Dutch schoolboys.

DESIGN AND PARTICIPANTS

As a part of routine school medical examinations, during a 2-year period (2001-3), testis position was determined in 6-year, 9-year and 13-year-old schoolboys. Before the examination, a parent questionnaire was sent inquiring both about the position of the testes and whether the child had been admitted earlier to hospital for orchidopexy. In 6-year and 13-year olds, a physical examination was performed by the school medical officer; in 9-year olds, a school nurse interview was held. Each boy for whom there was any doubt of the scrotal position was referred to the hospital for examination of both testes.

SETTING

Institution for Youth Health Care "Noordkennemerland" and Medical Centre Alkmaar, Alkmaar, the Netherlands.

RESULTS

Testis position was determined in 2042 boys aged 6, 1038 aged 9 and 353 aged 13. Of these, 47, 53 and 8 boys, respectively, were referred to the hospital and seen for further evaluation. The diagnosis of acquired UDT was made in 25 boys aged 6, 23 aged 9 and four aged 13. In 33 boys, a congenital UDT was diagnosed; 32 (97%) had already been diagnosed and treated at an early age.

CONCLUSIONS

The prevalence of acquired UDT for 6-year, 9-year and 13-year olds was, respectively, 1.2% (25/2042), 2.2% (23/1038) and 1.1% (4/353). In addition, congenital UDT is treated during the early years of life and, in contrast with popular belief, screening programmes for detecting UDT in the early years are successful.

Environmental effects on hormonal regulation of testicular descent

Regulation of testicular descent is hormonally regulated, but the reasons for maldescent remain unknown in most cases. The main regulatory hormones are Leydig cell-derived testosterone and insulin-like factor 3 (INSL3). Luteinizing hormone (LH) stimulates the secretion of these hormones, but the secretory responses to LH are different: INSL3 secretion increases slowly and may reflect the LH dependent differentiated status of Leydig cells, whereas testosterone response to LH is immediate. Testosterone contributes to the involution of the suspensory ligament and to the inguinoscrotal phase of the descent, while INSL3 acts mainly in transabdominal descent by stimulating the growth of the gubernaculum. INSL3 acts through a G-protein coupled receptor LGR8. In the absence of either INSL3 or LGR8 mice remain cryptorchid. In humans only few INSL3 mutations have been described, whereas LGR8 mutations may cause some cases of undescended testis. Similarly, androgen insensitivity or androgen deficiency can cause cryptorchidism. Estrogens have been shown to down regulate INSL3 and thereby cause maldescent. Thus, a reduced androgen-estrogen ratio may disturb testicular descent. Environmental effects changing the ratio can thereby influence cryptorchidism rate. Estrogens and anti-androgens cause cryptorchidism in experimental animals. In our cohort study we found higher LH/testosterone ratios in 3-month-old cryptorchid boys than in normal control boys, suggesting that cryptorchid testes are not cabable of normal hormone secretion without increased gonadotropin drive. This may be either the cause or consequence of cryptorchidism. Some phthalates act as anti-androgens and cause cryptorchidism in rodents. In our human material we found an association of a high phthalate exposure with a high LH/testosterone ratio. We hypothesize that an exposure to a mixture of chemicals with anti-androgenic or estrogenic properties (either their own activity or their effect on androgen-estrogen ratio) may be involved in cryptorchidism.

Serum insulin-like growth factor-I (IGF-I) and growth in children born after assisted reproduction

CONTEXT

Concern has been raised about the safety of assisted reproduction techniques for the offspring.

OBJECTIVES

The objective of the study was to investigate postnatal growth and growth factors in children born after intra-cytoplasmatic sperm injection (ICSI) and in vitro fertilization (IVF).

DESIGN

The study had two cohorts: a population-based longitudinal infant cohort 0-36 months [236 ICSI, 173 IVF, 1530 naturally conceived (NC)], and a cross-sectional child cohort at 5 yr (68 ICSI, 67 IVF, 70 NC).

INTERVENTION

Anthropometrical measurements were made at birth, 3, 18, 36 (infant cohort), and 60 months (child cohort), and blood samples were collected at 3 or 60 months.

MAIN OUTCOME MEASURES

Serum IGF-I, IGFBP-3, height, weight, head and abdominal circumference, body mass index, and fat folds were the main outcome measures.

RESULTS

Anthropometrical measurements showed no significant differences between ICSI and IVF children and controls in either cohort. However, singleton ICSI girls [3.4 (0.6) kg, P = 0.008] had a slightly lower birth weight than IVF [3.5 (0.5) kg] and NC girls [3.5 (0.5) kg]. Birth weights of singleton boys [3.6 (0.5) kg], twin boys [2.6 (0.6) kg], and twin girls [2.4 (0.5) kg] did not differ between types of conception. In the infant cohort in 3-month-old singletons, serum IGF-I was lower in ICSI [78 (26) ng/ml] than NC boys [94 (27) ng/ml, P < 0.001] and IVF [74 (34) ng/ml], compared with NC girls [93 (43) ng/ml, P = 0.011]. ICSI children were also smaller than their target height (sd score) at 3 yr of age [mean -0.91 (1.2)], compared with NC children [-0.61 (0.9), P = 0.033]. In the child cohort, target height attainment (sd score) and growth factors did not differ among the three groups.

CONCLUSIONS

The overall growth pattern of ICSI and IVF children in both cohorts was normal. Our findings of subtle differences in target height attainment and serum IGF-I levels between infants born after assisted reproduction techniques and controls may not be clinically significant. However, these observations indicate that further systematic follow-up of growth and puberty in these children is needed.

Today's epidemics in children: possible relations to environmental pollution and suggested preventive measures

BACKGROUND

Facts and hypotheses on the relationship between some children's diseases or disorders and external stressors during the developmental stage of a child, both prenatally and postnatally are described in literature. In this paper the following changes in patterns and causes of the main childhood illnesses are summarized and recommendations for actions are made. Prematurity. Intra-uterine growth restriction. Testicular dysgenesis syndrome. Type I and Type II diabetes. Asthma, atopy and hay fever. Autism. Attention deficit hyperactivity disorder (ADHD). Learning disabilities. Cancer. Obesity. Hearing problems.

RESULTS

Literature provides a growing amount of information on changing patterns in childhood diseases.

CONCLUSIONS

The following recommendations for action are formulated: Immediate research on endocrine disrupters in relation to prematurity. Diabetes: avoid Maillard Compounds in liquid baby food and in food in general: promote breastfeeding. Asthma: avoid exposure to smoking, the use of chemical household products, dioxin and dioxin-like chemicals, and avoid air pollution with high levels of particulate matter, especially around conception, during pregnancy and in the first years of life. Autism: more research on incidence and causes. ADHD and learning disabilities: more research on prevalence and causes. Preventions: 1) preconception counselling to avoid potentially harmful substances; 2) controlling and further lowering levels of polychlorinated biphenyls, lead and methyl mercury. Cancer: promote breastfeeding, carry out research into effects of foetal exposure to internal fission-product radionuclides. Obesity: stop smoking in pregnancy, avoid parental obesity, longer night sleep. Hearing problems: lower noise levels in discothèques, promote the day-evening-night level to avoid noise (longer night sleep).

Maternal serum alpha-fetoprotein level during pregnancy and isolated cryptorchidism in male offspring

Cryptorchidism is thought to result from a disruption of the androgen-estrogen balance in utero. Alpha-fetoprotein (AFP) interacts with and may modulate fetal responses to estrogens. Using a cohort of boys born to women participating in a Danish maternal serum AFP screening program between 1980 and 1994, the authors explored whether AFP levels (as reflected by maternal serum AFP levels in gestational weeks 14-22) were associated with the risk of isolated cryptorchidism in male offspring. Cryptorchidism diagnoses and covariate information were obtained from Denmark's national health registries. Risk ratios for cryptorchidism by maternal serum AFP multiples of the median were estimated by use of log-linear binomial regression. Of 25,418 boys, 663 (2.6%) were diagnosed with cryptorchidism. After adjustment for confounders, boys with maternal serum AFP levels greater than or equal to 2.5 times the median had a 63% (95% confidence interval: -2, 172) greater risk of cryptorchidism than did boys with maternal serum AFP levels within 25% of the median. High fetal AFP levels may contribute directly to events producing cryptorchidism; alternatively, elevated maternal serum AFP levels may reflect placental dysfunction, some aspect of which contributes to cryptorchidism.

Xenobiotics with estrogen or antiandrogen action — disruptors of the male reproductive system

The environmental and life-style changes associated with developing industry and agriculture, especially the exposure to endocrine disrupting chemicals (xenobiotics), are considered as causes of the increasing incidence of male reproductive system disorders. Most of the xenobiotics, which harmfully influence the male reproductive system, reveal estrogen-like (xenoestrogens) or anti-androgenic activity. Recent data have revealed physiological roles of estrogens in the male, however, there are evidences that estrogen-like substances may lead to many undesirable symptoms in the male i.e. gonadal dysgenesis, genital malformations, cryptorchidism, decreased fertility potential and testicular neoplastic changes. The number of xenoestrogens is still growing in the environment, whereas the mechanisms of their action are still not exactly known. They can be harmful not only to the present but potentially also to the next generations.

Endocrine disrupting chemicals: a new and emerging public health problem?

Coordination of targeted toxicological studies is needed

Trends in childhood disease

Child mortality has declined remarkably during the last decades. While neonatal disorders, diarrhoea, pneumonia, and malaria as well as being underweight account for most of the child deaths worldwide, children's health discussions in Europe and the USA focus on other issues such as asthma, neurodevelopmental disorders, male genital malformations, and childhood cancer. There is clear evidence of increasing rates of asthma in various countries during the last decades, although rates in some countries may now have stabilised or even decline as recent UK data indicate. Although an increase in the frequency of neurodevelopmental disorders such as autism and attention deficit disorder has frequently been discussed, the limited data in this field does not justify such a conclusion. While geographic heterogeneity regarding reproductive outcomes is apparent, global trends have not been identified. Interpretation of the available information on asthma, neurodevelopmental disorders and reproductive outcomes is hampered by inconstant diagnostic criteria over place and time and the lack of good and comprehensive population-based surveillance data, which makes it impossible to ascertain trends in actual disease frequency. Data indicate that developed countries have a gradually increasing incidence in leukaemia with a corresponding drop in the incidence of lymphoma. Increases in brain tumour frequency may be related to the development and wide application of new diagnostic capabilities, rather than a true change in the incidence of malignant disease. With a better prognosis for childhood cancer survival, secondary cancers following chemotherapy appear to be increasing. A wide range of environmental factors is thought to have an impact on children's health. These factors include nutrition (protein, vitamins, antioxidants), lifestyle and behaviour choices such as tobacco and alcohol use, parental health, socio-economic status, choice of living environment (urban versus rural, etc.), and parent-sibling behaviour. From the available data, no general conclusions on the contribution of specific chemicals can be drawn.

Persistent pesticides in human breast milk and cryptorchidism

INTRODUCTION

Prenatal exposure to some pesticides can adversely affect male reproductive health in animals. We investigated a possible human association between maternal exposure to 27 organochlorine compounds used as pesticides and cryptorchidism among male children.

DESIGN

Within a prospective birth cohort, we performed a case-control study; 62 milk samples from mothers of cryptorchid boys and 68 from mothers of healthy boys were selected. Milk was collected as individual pools between 1 and 3 months postpartum and analyzed for 27 organochlorine pesticides.

RESULTS

Eight organochlorine pesticides were measurable in all samples (medians; nanograms per gram lipid) for cases/controls: 1,1-dichloro-2,2-bis(4-chlorophenyl) ethylene (p,p -DDE) : 97.3/83.8; beta-hexachlorocyclohexane (beta-HCH) : 13.6/12.3; hexachlorobenzene (HCB) : 10.6/8.8; alpha-endosulfan: 7.0/6.7; oxychlordane: 4.5/4.1; 1,1,1-trichloro-2,2-bis(4-chlorophenyl) ethane (p,p -DDT) : 4.6/4.0; dieldrin: 4.1/3.1 ; cis-heptachloroepoxide (cis-HE) : 2.5/2.2. Five compounds [octachlorostyrene (OCS); pentachlorobenzene, 1,1-dichloro-2,2-bis(4-chlorophenyl) ethane(p,p -DDD) ; o,p -DDT ; mirex] were measurable in most samples (detection rates 90.8-99.2%) but in lower concentrations. For methoxychlor, cis-chlordane, pentachloroanisole (PCA), gamma-HCH, 1,1-dichloro-2-(2-chlorophenyl) -2,2(4-chlorophenyl) ethane, trans-chlordane, alpha-HCH, and o,p -DDE, both concentrations and detection rates were low (26.5-71.5%). Heptachlor, HCH (lc delta, epsilon), aldrin, beta-endosulfan and trans-heptachloroepoxide were detected at negligible concentrations and low detection rates and were not analyzed further. Seventeen of 21 organochlorine pesticides [p,p -DDT, p,p-DDE, p,p-DDD, o,p-DDT, HCH (alpha, beta, gamma), HCB, PCA, alpha-endosulfan, cis-HE, chlordane (cis-, trans-) oxychlordane, methoxychlor, OCS, and dieldrin] were measured in higher median concentrations in case milk than in control milk. Apart from trans-chlordane (p = 0.012), there were no significant differences between cryptorchid and healthy boys for individual chemicals. However, combined statistical analysis of the eight most abundant persistent pesticides showed that pesticide levels in breast milk were significantly higher in boys with cryptorchidism (p = 0.032).

CONCLUSION

The association between congenital cryptorchidism and some persistent pesticides in breast milk as a proxy for maternal exposure suggests that testicular descent in the fetus may be adversely affected.

Larger testes and higher inhibin B levels in Finnish than in Danish newborn boys

CONTEXT

Recent studies showed that male reproductive health problems, such as cryptorchidism, hypospadias, testicular cancer, and low sperm quality, are more prevalent in Denmark than in Finland.

OBJECTIVES

We hypothesized that, if fetal testicular dysgenesis contributed to these observations, differences in gonadal development and the hypothalamus-pituitary-testis axis would already be detectable perinatally. Thus, we investigated healthy newborn boys in both countries.

DESIGN

This was a prospective, longitudinal population-based study.

SETTING

Two primary obstetric centers were included at the University Hospitals of Copenhagen, Denmark, and Turku, Finland.

PARTICIPANTS

The participants of the study included 633 Danish and 1044 Finnish boys, born at term with appropriate weight for gestational age.

INTERVENTIONS

Ultrasound determination of testis size at 0, 3, and 18 months and blood sampling (n = 727) at 3 months were analyzed.

MAIN OUTCOME MEASURES

Testicular volume and reproductive hormones were measured.

RESULTS

Testis volume was significantly higher at all ages in Finnish than in Danish boys (medians, 98 vs. 95, 185 vs. 119, and 188 vs. 136 mm(3), respectively; P < 0.00001). Testis growth from birth to 3 months was larger in Finnish than in Danish boys (mean, 75 vs. 26 mm(3); P < 0.0001). Serum hormone levels were higher in Finnish than Danish boys for inhibin B (median, 456 vs. 385 pg/ml; P < 0.0001), FSH (1.33 vs. 1.21 IU/liter; P < 0.036), and SHBG (143 vs. 136 nmol/liter; P < 0.022). Inhibin B was significantly positively correlated to testicular volume (r = 0.25; P < 0.006).

CONCLUSIONS

The larger testes and higher inhibin B levels most likely represent a bigger volume of seminiferous tubules in Finnish compared with Danish boys. Although this phenomenon may be attributable to a genetic difference between the two countries, it may also reflect environmental factors influencing testicular development.

Recent advances in external genitalia

In the last decade, significant progress in the knowledge and management of external genital anomalies has been achieved, including an improved understanding of epidemiology and pathophysiology of these anomalies, the identification of etiologic genetic defects, and significant improvements in surgical approaches that have decreased complications and improved cosmetic outcomes. We highlight the most clinically important advances of the commonly encountered external genital anomalies.

The sensitivity of the child to sex steroids: possible impact of exogenous estrogens

The current trends of increasing incidences of testis, breast and prostate cancers are poorly understood, although it is assumed that sex hormones play a role. Disrupted sex hormone action is also believed to be involved in the increased occurrence of genital abnormalities among newborn boys and precocious puberty in girls. In this article, recent literature on sex steroid levels and their physiological roles during childhood is reviewed. It is concluded that (i) circulating levels of estradiol in prepubertal children are lower than originally claimed; (ii) children are extremely sensitive to estradiol and may respond with increased growth and/or breast development even at serum levels below the current detection limits; (iii) no threshold has been established, below which no hormonal effects can be seen in children exposed to exogenous steroids or endocrine disruptors; (iv) changes in hormone levels during fetal and prepubertal development may have severe effects in adult life and (v) the daily production rates of sex steroids in children estimated by the Food and Drug Administration in 1999 and still used in risk assessments are highly overestimated and should be revised. Because no lower threshold for estrogenic action has been established, caution should be taken to avoid unnecessary exposure of fetuses and children to exogenous sex steroids and endocrine disruptors, even at very low levels.

Pubertal development in Danish children: comparison of recent European and US data

Two recent epidemiological studies (PROS and NHANES III) from the USA noted earlier sexual maturation in girls, leading to increased attention internationally to the age at onset of puberty. We studied the timing of puberty in a large cohort of healthy Danish children in order to evaluate differences between USA and Denmark, as well as to look for possible secular trends in pubertal development. Healthy Caucasian children from public schools in Denmark participated in the study which was carried out in 1991-1993. A total number of 826 boys and 1,100 girls (aged 6.0-19.9 years) were included, and pubertal stages were assessed by clinical examination according to methods of Tanner. In boys testicular volume was determined using an orchidometer. We found that age at breast development 2 (B2) was 10.88 years, and mean menarcheal age was 13.42 years. Girls with body mass index (BMI) above the median had significantly earlier puberty (age at B2 10.42 years) compared with girls with BMI below the median (age at B2 11.24 years, p < 0.0001). Similarly, menarcheal age was significantly lower in girls with BMI above the median compared with girls with BMI below the median (13.12 vs. 13.70 years, p = 0.0012). In Danish boys we found that age at genital stage 2 (G2) was 11.83 years. Both sexes were significantly taller compared with data from 1964, but timing of pubertal maturation seemed unaltered. Finally, puberty occurred much later in Denmark compared with recent data from USA. We could not detect any downwards secular trend in the timing of puberty in Denmark between 1964 and 1991-1993 as seen in the US. Obesity certainly plays a role in the timing of puberty, but the marked differences between Denmark and USA cannot be attributed exclusively to differences in BMI. A possible role of other factors like genetic polymorphisms, nutrition, physical activity or endocrine disrupting chemicals must therefore also be considered. Therefore, we believe it is crucial to monitor the pubertal development closely in Denmark in the coming decades.

Low Birth Weight and Male Reproductive Function

Scientific interest in morbidity in children born small for gestational age (SGA) has increased considerably over the last few decades. The elevated risk of cardiovascular and metabolic diseases in adulthood in individuals born SGA has been well documented, whereas data on gonadal development are limited. Prospective studies, case-control investigations and registry surveys show that impaired intrauterine growth increases the risks of congenital hypospadias, cryptorchidism and testicular cancer approximately two- to threefold. Although few studies focus on the effect of intrauterine growth on male pubertal development, testicular hormone production or sperm quality, available evidence points towards a subtle impairment of both Sertoli cell and Leydig cell function. Animal studies support the hypothesis that impaired perinatal growth restriction, depending on the timing, can affect postnatal testis size and function into adulthood. Current human data, however, are often based on highly selected hospital populations and lack precise distinctions between low birth weight, SGA, timing of growth restriction and a differentiation of catch-up growth patterns. Despite the methodological inadequacies of individual study results, the combined evidence from all data leaves little doubt that fetal growth restriction is associated with increased risk of male reproductive health problems, including hypospadias, cryptorchidism and testicular cancer.

Nouvelles avancées dans l’étude de l’influence de l’environnement sur la santé reproductive masculine

BACKGROUND

An important part of the research effort on male reproductive health focus on two important questions: on the one side, that of the temporal deterioration of male reproductive health and, on the other head, that of the influence of exposure to environmental chemicals during intra-uterine life on health during childhood and adulthood. The concepts on endocrine disruption and testicular dysgenesis syndrome make a link between these two questions.

METHODS

This work examines knowledge cumulated over the last couple of years concerning geographical and temporal variations in male reproductive health and the testicular dysgenesis syndrome. Recent results concerning the concept of endocrine disruption and on the environmental influences on male reproduction are presented, as well as on the transgenerational effects on environmental factors on the health of male children.

CONCLUSIONS

Based on clinical and epidemiological data, and with the use of in vitro animal models as well as observations in wildlife, research in this field has enabled progress in the elucidation of mechanisms of action and characterization of environmental influences on male reproductive health.

Developmental model for the pathogenesis of testicular carcinoma in situ: genetic and environmental aspects

Carcinoma in situ testis (CIS), also known as intratubular germ cell neoplasia (ITGCN), is a pre-invasive precursor of testicular germ cell tumours, the commonest cancer type of male adolescents and young adults. In this review, evidence supporting the hypothesis of developmental origin of testicular germ cell cancer is summarized, and the current concepts regarding aetiology and pathogenesis of this disease are critically discussed. Comparative studies of cell surface proteins (e.g. PLAP and KIT), some of the germ cell-specific markers (e.g. MAGEA4, VASA, TSPY and NY-ESO-1), supported by studies of regulatory elements of the cell cycle (e.g. p53, CHK2 and p19-INK4d) demonstrated a close similarity of CIS to primordial germ cells and gonocytes, consistent with the pre-meiotic origin of CIS. Recent gene expression profiling studies showed that CIS cells closely resemble embryonic stem cells (ESCs). The abundance of factors associated with pluripotency (NANOG and OCT-3/4) and undifferentiated state (AP-2gamma) may explain the remarkable pluripotency of germ cell neoplasms, which are capable of differentiating to various somatic tissue components of teratomas. Impaired gonadal development resulting in the arrest of gonocyte differentiation and retention of its embryonic features, associated with an increasing genomic instability, is the most probable model for the pathogenesis of CIS. Genomic amplification of certain chromosomal regions, e.g. 12p, may facilitate survival of CIS and further invasive progression. Genetic studies, have so far not identified gene polymorphisms predisposing to the most common non-familial testicular cancer, but this research has only recently begun. Association of CIS with other disorders, such as congenital genital malformations and some forms of impaired spermatogenesis, all rising in incidence in a synchronous manner, led to the hypothesis that CIS might be a manifestation of testicular dysgenesis syndrome (TDS). The aetiology of TDS including testicular cancer remains to be elucidated, but epidemiological trends suggest a primary role for environmental factors, probably combined with genetic susceptibility.

Testicular dysgenesis syndrome: possible role of endocrine disrupters

The testicular dysgenesis syndrome (TDS) hypothesis proposes that the four conditions cryptorchidism, hypospadias, impaired spermatogenesis and testis cancer may all be manifestations of disturbed prenatal testicular development. The TDS hypothesis is based on epidemiological, clinical and molecular studies, all suggestive of an interrelation between the different symptoms. The aetiology of TDS is suspected to be related to genetic and/or environmental factors, including endocrine disrupters. Few human studies have found associations/correlations between endocrine disrupters, including phthalates, and the different TDS components. However, for ethical reasons, evidence of a causal relationship between prenatal exposure and TDS is inherently difficult to establish in human studies, rendering the recently developed animal TDS model an important tool for investigating the pathogenesis of TDS. Clinically, the most common manifestation of TDS is probably a reduced sperm concentration, whereas the more severe form may include a high risk of testis cancer. Clinicians should be aware of the interconnection between the different features of TDS, and inclusion of a programme for early detection of testis cancer in the management of infertile men with poor semen quality is recommended.