Low Birth Weight Is Associated with a Decreased Overall Adult Health Status and Reproductive Capability - Results of a Cross-Sectional Study in Primary Infertile Patients

The impact of impaired intrauterine growth on male fertility: A systematic review and meta-analysis

BACKGROUND

Adverse intrauterine environment was believed to have deleterious effects on the gonadal function. However, the association between impaired intrauterine growth and fertility in adult males has not been established.

OBJECTIVES

To compare the reproductive rates of males born small for gestational age (SGA), with low birth weight (LBW) or very low birth weight (VLBW) with control groups.

METHODS

The Preferred Reporting Items for Systematic reviews and Meta-Analyses (PRISMA) statement was followed to search PubMed, Web of Science, Cochrane Library, and Embase databases from inception to June 16, 2023. Cohort studies investigating the reproductive rates of males born SGA, with LBW or VLBW were included. A random or fixed effects model was used for different exposures.

RESULTS

A total of 10 studies out of 3,801 records were included. Males born SGA showed a higher risk of infertility than the control group (odds ratio, OR = 0.91, 95% confidence interval, 95% CI 0.89-0.93, p = 0.000). The reproductive rates of individuals born with LBW or VLBW were lower than the control group (OR = 0.86, 95% CI 0.78-0.94, p = 0.001; OR = 0.57, 95% CI 0.40-0.81, p = 0.002, respectively). Participants were further divided into two age groups of 18-35 and 35-45 years. In both subgroups, the reproductive rates were lower in males born SGA, with LBW or VLBW compared with controls. Sensitivity analysis showed the robustness of the pooled estimates among LBW and VLBW.

CONCLUSION

In summary, SGA, LBW, and VLBW were associated with a higher risk of male infertility in both early and middle adulthood. Achieving optimal intrauterine growth would be helpful to prevent male infertility.

Low Birth Weight is Associated with Sperm DNA Fragmentation and Assisted Reproductive Technology Outcomes in Primary Infertile Men: Results of a Cross-Sectional Study

PURPOSE

To assess the relationship between clinical and semen characteristics and assisted reproductive technology (ART) outcomes with different birth weight (BW) categories in a cohort of infertile men.

MATERIALS AND METHODS

Data from 1,063 infertile men were analyzed. Patients with BW ≤2,500, 2,500-4,000, and ≥4,000 g were considered as having low BW (LBW), normal BW (NBW), and high BW (HBW), respectively. Testicular volume (TV) was assessed with a Prader orchidometer. Serum hormones were measured in all cases. Semen analyses were categorized based on 2021 World Health Organization reference criteria. Sperm DNA fragmentation (SDF) was tested in every patient and considered pathological for SDF >30%. ART outcomes were available for 282 (26.5%) patients. Descriptive statistics and logistic regression analyses detailed the association between semen parameters and clinical characteristics and the defined BW categories.

RESULTS

Of all, LBW, NBW, and HBW categories were found in 79 (7.5%), 807 (76.0%), and 177 (16.5%) men, respectively. LBW men had smaller TV, presented higher follicle-stimulating hormone (FSH) but lower total testosterone levels compared to other groups (all p<0.01). Sperm progressive motility (p=0.01) and normal morphology (p<0.01) were lower and SDF values were higher (all p<0.01) in LBW compared to other groups. ART pregnancy outcomes were lower in LBW compared to both NBW and HBW categories (26.1% vs. 34.5% vs. 34.5%, p=0.01). At multivariable logistic regression analysis, LBW was associated with SDF >30% (odd ratio [OR] 3.7; p<0.001), after accounting for age, Charlson Comorbidity Index (CCI), FSH, and TV. Similarly, LBW (OR 2.2; p<0.001), SDF >30% (OR 2.9; p<0.001) and partner's age (OR 1.3; p=0.001) were associated with negative ART outcomes, after accounting for the same predictors.

CONCLUSIONS

LBW was associated with impaired clinical and semen characteristics in infertile men compared to both NBW and HBW. SDF and ART outcomes were significantly worse in the LBW group.

Low testosterone at age 31 associates with maternal obesity and higher body mass index from childhood until age 46: A birth cohort study

BACKGROUND

Low testosterone (T) levels in men associate with increased risks of obesity, type 2 diabetes, metabolic syndrome, and cardiovascular diseases. However, most studies are cross-sectional with follow-up-time < 10 years, and data on early growth are limited.

OBJECTIVE

To compare prenatal factors and body mass index (BMI) development from birth to age 46 in relation to low T at age 31.

MATERIALS AND METHODS

Men with low T (T < 12.1 nmol/L, n = 132) and men with normal T at age 31 (n = 2561) were derived from the Northern Finland Birth Cohort 1966. Prenatal factors, longitudinal weight and height data from birth to age 14, and cross-sectional weight and height data at ages 31 and 46, and waist-hip-ratio (WHR) and T levels at age 31 were analyzed. Longitudinal modeling and timing of adiposity rebound (AR, second BMI rise at age 5-7 years) were calculated from fitted BMI curves. Results were adjusted for mother's pre-pregnancy BMI and smoking status, birth weight for gestational age, alcohol consumption, education level, smoking status, and WHR at age 31.

RESULTS

Neither gestational age nor birth weight was associated with low T at age 31; however, maternal obesity during gestation was more prevalent among men with low T (9.8% vs. 3.5%, adjusted aOR: 2.43 [1.19-4.98]). Men with low T had earlier AR (5.28 vs. 5.82, aOR: 0.73 [0.56-0.94]) and higher BMI (p < 0.001) from AR onward until age 46. Men with both early AR and low T had the highest BMI from AR onward.

CONCLUSIONS

In men, maternal obesity and early weight gain associate with lower T levels at age 31, independently of adulthood abdominal obesity. Given the well-known health risks related to obesity, and the rising prevalence of maternal obesity, the results of the present study emphasize the importance of preventing obesity that may also affect the later reproductive health of the offspring.

Male Infertility and the Risk of Developing Testicular Cancer: A Critical Contemporary Literature Review

Background and Objectives: The relationship between male infertility (MI) and testicular cancer (TC) is bilateral. On one hand, it is well-established that patients diagnosed with TC have a high risk of pre- and post-treatment infertility. On the other hand, the risk of developing TC in male infertile patients is not clearly defined. The objective of this review is to analyze the histopathological, etiological, and epidemiological associations between MI and the risk of developing testicular cancer. This review aims to provide further insights and offer a guide for assessing the risk factors for TC in infertile men. Materials and Methods: A comprehensive literature search was conducted to identify relevant studies discussing the relationship between MI and the risk of developing TC. Results: The incidence rates of germ cell neoplasia in situ (GCNIS) appear to be high in infertile men, particularly in those with low sperm counts. Most epidemiological studies have found a statistically significant risk of developing TC among infertile men compared to the general or fertile male populations. The concept of Testicular Dysgenesis Syndrome provides an explanatory model for the common etiology of MI, TC, cryptorchidism, and hypospadias. Clinical findings such as a history of cryptorchidism could increase the risk of developing TC in infertile men. Scrotal ultrasound evaluation for testis lesions and microlithiasis is important in infertile men. Sperm analysis parameters can be useful in assessing the risk of TC among infertile men. In the future, sperm and serum microRNAs (miRNAs) may be utilized for the non-invasive early diagnosis of TC and GCNIS in infertile men. Conclusions: MI is indeed a risk factor for developing testicular cancer, as demonstrated by various studies. All infertile men should undergo a risk assessment using clinical examination, ultrasound, and semen parameters to evaluate their risk of TC.

Pre- and peripubertal sex steroids are inversely associated with birth weight in preterm boys

OBJECTIVE

The relationship between sex hormone concentrations during childhood and birth weight (BW) is poorly understood. We aimed to investigate this relationship and the associations with anthropometric data at 5, 6, 7, 8, and 10 years of age in preterm boys.

DESIGN

A prospective longitudinal single-centre study, including 58 boys with a BW of 1325-3320 g and gestational age (GA) of 32 + 2 to 36 + 6 weeks.

PATIENTS AND MEASUREMENTS

Data on GA, BW and anthropometric data between 5 and 10 years of age were recorded. Testicular development was assessed at 8 and 10 years of age. Serum concentrations of sex steroids were analysed with gas chromatography-tandem mass spectrometry at 5-10 years and luteinizing hormone (LH) and follicle-stimulating hormone (FSH) with immunoassays at 10 years of age.

RESULTS

At 8 years of age, testosterone and estrone correlated negatively with BW, (ρ = -0.35, p = .021) and (ρ = -0.34, p = .024), respectively. At 10 years of age, testosterone, dihydrotestosterone, estrone and estradiol correlated negatively with BW (ρ = -0.39, p = .010), (ρ = -0.38, p = .013), (ρ = -0.44, p = .003) and (ρ = -0.36, p = .019), respectively. Weight gain from birth correlated with testosterone at 5 years (ρ = 0.40, p = .002), 7 years (ρ = 0.30, p = .040), 8 years (ρ = 0.44, p = .003) and 10 years (ρ = 0.40, p = .008) of age. At 10 years of age, testosterone correlated with LH (ρ = 0.42, p = .006) and FSH (ρ = 0.33, p = .033) but not with testicular volume.

CONCLUSIONS

Lower BW was associated with increased sex steroid concentrations from 8 years of age, independently of clinical signs of puberty.

Growth, puberty and testicular function in boys born small for gestational age with a nonspecific disorder of sex development

OBJECTIVE

Being born small for gestational age (SGA) is frequently associated with unexplained disorders of sex development (nonspecific DSD) in boys. Little is known about their future growth, puberty and testicular function. Our objective is to determine the long-term endocrine outcome of boys born SGA who have a nonspecific DSD.

DESIGN

Boys with a nonspecific DSD born SGA and appropriate for GA (AGA) were retrieved through the International Disorders of Sex Development registry and retrospective data collected, based on a spreadsheet containing 102 items.

PATIENTS AND MEASUREMENTS

In total, 179 boys were included, of which 115 were born SGA and 64 were born AGA. Their growth and pubertal development were compared. Serum LH, FSH, testosterone, AMH and inhibin B levels in infancy and puberty were analysed to assess testicular function.

RESULTS

At 2 years of age, 30% of SGA boys had incomplete or absent catch-up growth. Boys born SGA also had higher LH during minipuberty and lower testosterone in stimulation tests (p = 0.037 and 0.040, respectively), as compared to boys born AGA. No differences were observed in timing or course of puberty or end-pubertal hormone levels.

CONCLUSIONS

Almost one out of three SGA boys with a nonspecific DSD experiences insufficient catch-up growth. In addition, our data suggest dysfunction of infantile Leydig cells or altered regulation of the hypothalamic-pituitary-gonadal axis in SGA boys during childhood. Sex steroid production during puberty seems unaffected.

Men born small for gestational age or with low birth weight do not improve their rate of reproduction over time: a Swedish population-based study

OBJECTIVE

To investigate whether the reduced reproductive rate among men born small for gestational age (SGA) or with low birth weight (LBW) is present after up to 44 years of follow-up.

DESIGN

Population-based register study.

SETTING

National registers in Sweden.

PATIENT(S)

All men born in Sweden between 1973 and 1993 (n = 1,045,167) followed up to 2018.

INTERVENTION(S)

None.

MAIN OUTCOME MEASURE(S)

Registered fatherhood, infertility diagnoses, and fertility treatments obtained from registers up to 2018 RESULT(S): Men born SGA or with LBW have a lower chance of becoming fathers than men born with normal birth characteristics: hazard ratio (95% confidence interval) 0.91 (0.90-0.92) and 0.88 (0.86-0.90), respectively. The reduction in reproductive rate is more evident after a longer follow-up time. Men born SGA were more likely to receive a diagnosis of infertility. Sperm donation and intracytoplasmic sperm injection were more often used in men born SGA, further strengthening the hypothesis of an association between birth characteristics and male infertility.

CONCLUSION(S)

Men born SGA or with LBW have a lower chance of becoming fathers, but the reduction in fertility is smaller for the younger cohort. Further studies are needed to determine if this difference is maintained.

Exploring the evidence for epigenetic regulation of environmental influences on child health across generations

Environmental exposures, psychosocial stressors and nutrition are all potentially important influences that may impact health outcomes directly or via interactions with the genome or epigenome over generations. While there have been clear successes in large-scale human genetic studies in recent decades, there is still a substantial amount of missing heritability to be elucidated for complex childhood disorders. Mounting evidence, primarily in animals, suggests environmental exposures may generate or perpetuate altered health outcomes across one or more generations. One putative mechanism for these environmental health effects is via altered epigenetic regulation. This review highlights the current epidemiologic literature and supporting animal studies that describe intergenerational and transgenerational health effects of environmental exposures. Both maternal and paternal exposures and transmission patterns are considered, with attention paid to the attendant ethical, legal and social implications.

Racial/ethnic differences in maternal resilience and associations with low birthweight

OBJECTIVE

Evaluate racial/ethnic differences in maternal resilience and its associations with low birthweight (LBW).

STUDY DESIGN

Retrospective cohort study of 3244 women surveyed in the Longitudinal Study of Adolescent to Adult Health. The Add Health Resilience Instrument assessed resilience. Logistic regression models explored associations between women's resilience and risk of LBW.

RESULT

Resilience scores were lowest in American Indian women. Women with the lowest resilience scores were more likely to deliver a LBW infant than highly resilient women, after adjusting for demographic and health-related factors (aOR 1.58 95% CI 1.05-2.38). The risk-adjusted rate of LBW among highly resilient Black women (15.6%) was significantly higher than the risk-adjusted rate of LBW among highly resilient white women (9.1%, p = 0.01) and highly resilient Hispanic women (8.6%, p = 0.04).

CONCLUSION

Resilience scores differ significantly among women of different race and ethnicity but do not appear to entirely account for racial/ethnic disparities in LBW.

The Relation of Birth Weight and Adiposity Across the Life Course to Semen Quality in Middle Age

BACKGROUND

Studies of body mass index and semen quality have reported mixed results, but almost all were cross-sectional and many were conducted in selected populations. Longitudinal studies in population-based cohorts are necessary to identify how timing and duration of excess adiposity may affect semen quality.

METHODS

In 193 members of the Child Health and Development Studies birth cohort, we examined associations of birth weight and adiposity at six time points spanning early childhood and adulthood with sperm concentration, motility, and morphology at mean age 44 years, as well as with corresponding 2010 World Health Organization (WHO) subfertility reference levels.

RESULTS

Birth weight for gestational age percentile was positively associated with square-root sperm concentration (regression coefficient B [95% confidence interval] = 0.02 × 103 sperm/ml [0.004, 0.04]). Overweight/obesity in men's 20s was associated with lower percent progressive motility (B =-5.2 [-9.9, -0.63]), higher odds of low motility (odds ratio (OR) = 2.4 [1.3, 4.4]), and higher odds of poor morphology (OR = 1.9 [0.94, 3.8]). Those who were overweight/obese in their 20s were also more likely to meet two or three WHO subfertility criteria (OR = 3.9 [1.6, 9.4]) compared with normal-weight men. Each additional adult decade in which a participant was overweight/obese was associated with higher odds of low motility (OR = 1.3 [0.96, 1.6]) and higher odds of meeting two or three WHO subfertility criteria (OR = 1.5 [1.0, 2.2]).

CONCLUSIONS

In our data, associations among adiposity and sperm concentration, motility, and morphology varied according to timing and duration of exposure, potentially reflecting different biological mechanisms that influence these semen parameters.

Birth characteristics in men with infertility

RESEARCH QUESTION

Are low birth weight, prematurity, being born small for gestational age, or both, associated with a higher risk of male factor infertility in adulthood?

DESIGN

Retrospective study of a clinical sample of 892 men, diagnosed with an infertility factor (male, female, combined or unexplained) together with their female partner at a University Hospital clinic in Sweden between 2005 and 2010. Data on birth weight and gestational age at birth were retrieved from the Swedish Medical Birth Register. The distribution of non-optimal birth characteristics in relation to infertility factor was described. A control group was created consisting of two men for each index man, born in Sweden in the same year as each index men, as well as a reference group consisting of all men born in Sweden the same years.

RESULTS

The likelihood of having been born small for gestational age was almost fivefold higher in men with male factor infertility than in men with unexplained infertility (OR 4.84, 95% CI 1.32 to 17.80). Men with male factor infertility were more often born with non-optimal birth characteristics than the control group (14.8% versus 8.5%; P = 0.010) and the reference group (14.8% versus 11.4%; P < 0.001). Men with azoospermia were more often born with non-optimal birth characteristics, compared with men without azoospermia (21.3% versus 12.1%; P = 0.038).

CONCLUSIONS

The results suggest an association between intrauterine growth restriction and male factor infertility in adulthood.

Maternal Protein Restriction Modulates Angiogenesis and AQP9 Expression Leading to a Delay in Postnatal Epididymal Development in Rat

The maternal nutritional status is essential to the health and well-being of the fetus. Maternal protein restriction during the perinatal stage causes sperm alterations in the offspring that are associated with epididymal dysfunctions. Vascular endothelial growth factor (VEGF) and its receptor, VEGFr-2, as well as aquaporins (AQPs) are important regulators of angiogenesis and the epididymal microenvironment and are associated with male fertility. We investigated the effects of maternal protein restriction on epididymal angiogenesis and AQP expression in the early stages of postnatal epididymal development. Pregnant rats were divided into two experimental groups that received either a normoprotein (17% protein) or low-protein diet (6% protein) during gestation and lactation. At postnatal day (PND)7 and PND14, male offspring were euthanized, the epididymides were subjected to morphometric and microvascular density analyses and to VEGF-A, VEGF-r2, AQP1 and AQP9 expression analyses. The maternal low-protein diet decreased AQP9 and VEGFr-2 expression, decreased epididymal microvascularity and altered the morphometric features of the epididymal epithelium; no changes in AQP1 expression were observed at the beginning of postnatal epididymal development. Maternal protein restriction alters microvascularization and affects molecules involved in the epidydimal microenvironment, resulting in morphometric alterations related to a delay in the beginning of epididymis postnatal development.

Nutritional adversity, sex and reproduction: 30 years of DOHaD and what have we learned?

It is well established that early life environmental signals, including nutrition, set the stage for long-term health and disease risk - effects that span multiple generations. This relationship begins early, in the periconceptional period and extends into embryonic, fetal and early infant phases of life. Now known as the Developmental Origins of Health and Disease (DOHaD), this concept describes the adaptations that a developing organism makes in response to early life cues, resulting in adjustments in homeostatic systems that may prove maladaptive in postnatal life, leading to an increased risk of chronic disease and/or the inheritance of risk factors across generations. Reproductive maturation and function is similarly influenced by early life events. This should not be surprising, since primordial germ cells are established early in life and thus vulnerable to early life adversity. A multitude of 'modifying' cues inducing developmental adaptations have been identified that result in changes in reproductive development and impairments in reproductive function. Many types of nutritional challenges including caloric restriction, macronutrient excess and micronutrient insufficiencies have been shown to induce early life adaptations that produce long-term reproductive dysfunction. Many pathways have been suggested to underpin these associations, including epigenetic reprogramming of germ cells. While the mechanisms still remain to be fully investigated, it is clear that a lifecourse approach to understanding lifetime reproductive function is necessary. Furthermore, investigations of the impacts of early life adversity must be extended to include the paternal environment, especially in epidemiological and clinical studies of offspring reproductive function.

Maternal protein malnutrition: effects on prostate development and adult disease

Well-controlled intrauterine development is an essential condition for many aspects of normal adult physiology and health. This process is disrupted by poor maternal nutrition status during pregnancy. Indeed, physiological adaptations occur in the fetus to ensure nutrient supply to the most vital organs at the expense of the others, leading to irreversible consequences in tissue formation and differentiation. Evidence indicates that maternal undernutrition in early life promotes changes in key hormones, such as glucocorticoids, growth hormones, insulin-like growth factors, estrogens and androgens, during fetal development. These alterations can directly or indirectly affect hormone release, hormone receptor expression/distribution, cellular function or tissue organization, and impair tissue growth, differentiation and maturation to exert profound long-term effects on the offspring. Within the male reproductive system, maternal protein malnutrition alters development, structure, and function of the gonads, testes and prostate gland. Consequently, these changes impair the reproductive capacity of the male offspring. Further, permanent alterations in the prostate gland occur at the molecular and cellular level and thereby affect the onset of late life diseases such as prostatitis, hyperplasia and even prostate cancer. This review assembles current thoughts on the concepts and mechanisms behind the developmental origins of health and disease as they relate to protein malnutrition, and highlights the effects of maternal protein malnutrition on rat prostate development and homeostasis. Such insights on developmental trajectories of adult-onset prostate disease may help provide a foundation for future studies in this field.

"The next-generation": Long-term reproductive outcome of adults born at a very low birth weight

BACKGROUND

Preterm birth at very low birth weight (VLBW, <1500g) has a multitude of consequences that extend to various aspects of adult life. Little is known about the long-term reproductive outcome of VLBW that survive to adulthood.

AIMS

To evaluate the reproductive outcome of VLBW infants who survive to adulthood (next-generation).

STUDY DESIGN

Retrospective cohort.

SUBJECTS

Infants born at a single tertiary center between the years 1982-1997 who survived to 18years of age (first-generation).

OUTCOME MEASURES

The number and the birth weight of offspring from adults born with VLBW were compared to those of other birth weight groups born in the same epoch: 1500-2499g, 2500-3799g (reference group) and ≥3800g. We calculated the ratio of actual compared to expected number of children in the next-generation for extreme birth weight parents, using the reference group as a control group and adjusting for birth year. Thereafter, we measured whether first-generation VLBW had an increased risk for a VLBW in the next-generation.

RESULTS

After exclusions, we identified first-generation 67,183 births, including 618 (9.2%) VLBW. There were 193 males and 184 female VLBW infants who survived to adulthood. Both female and male first-generation patients from the VLBW group had half the reproductive rate relative for the normal birth weight group. After adjusting for parental age, male and female VLBW survivors had no significant risk for a VLBW neonate in the next-generation, however, the overall number of are small and may limit any conclusion.

CONCLUSION

VLBW children who reach adulthood may be at a significantly lower reproductive capacity.