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

Abstract

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 ¼ 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.

Twinning during the pandemic

“…As a result, the ratio of male to female spontaneous abortions exceeds one in clinically recognized (i.e., after about 8 weeks of gestation) pregnancies [ 18 ]. The theory of selection in utero attributes this high ratio to the fact that males small at birth produce fewer offspring than do other males [ 19 ]. This relatively low reproductive fitness presumably arises, at least in part, from the relative frailty of small male infants.…”

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

“…Over the last decades emerging data has shown that in utero conditions might affect offsprings’ reproductive potential. In particular LBW, which is commonly used as a surrogate for impaired fetal growth and development, has been recognized to affect individual long-term somatic health as well as the gonadal and reproductive function [ 19 21 ]. Previous studies have explored the association between LBW and conventional semen parameters, but its impact on SDF and ART outcomes is currently poorly investigated.…”

“…However, whether being born with LBW could affect ART outcomes is still unknown. Liffner et al [ 19 ], in their Swedish population-based registry study, analyed data from 21,353 participants attending IVF clinics. They found that men born SGA were more likely to have needed donated spermatozoa to become fathers and were more likely to have used ICSI than men born appropriate for gestational age.…”

“…They found that men born SGA were more likely to have needed donated spermatozoa to become fathers and were more likely to have used ICSI than men born appropriate for gestational age. No differences in the total number of ART treatments or in the number of ART treatments needed to achieve the first delivery of a child were noted [ 19 ]. Our results show that the ART pregnancy rate was lower in LBW compared to both NBW and HBW categories (26.1% vs. 34.5% vs. 34.5%, p=0.01).…”

“…Previous studies have investigated the association between BW, as a marker of fetal development, and male reproductive parameters with conflicting findings. A Swedish population-based registry study reported that men born with low BW (LBW) had a lower chance of becoming fathers than men born with normal birth characteristics [ 19 ]. Similarly, an Italian case-control study with 1,200 young adults showed that the prevalence of LBW was higher in infertile participants compared to the fertile counterpart (8.6% vs. 3.2%) [ 20 ].…”