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

Fertility of young adults born very preterm/very low birth weight: An individual participant data meta-analysis

OBJECTIVES

To assess whether there are differences in fertility between adults born very preterm or at very low birth weight (VP/VLBW) with term-born controls, whether the association of VP/VLBW with fertility differs by sex, and which individual factors are associated with fertility among VP/VLBW adults.

STUDY DESIGN

Prospective longitudinal cohorts with fertility assessed in VP/VLBW and term-born adults were identified from two international consortia: Research on European Children and Adults Born Preterm (RECAP-Preterm), and Adults Born Preterm International Collaboration (APIC). Individual participant data (IPD) on neonatal, medical, sociodemographic, and fertility variables were collected and analyzed using a one-stage approach.

RESULTS

Seven cohorts with 931 VP/VLBW and 1363 term-born young adults (mean ages at assessment ranged from 23 to 30 years) were included. VP/VLBW and term-born young adults did not significantly differ in fertility (i.e., having children) (OR 1.48, 95 % CI 0.99-2.21). No moderation effect of sex could be confirmed (OR 0.87, 95 % CI 0.53-1.42). Among VP/VLBW young adults, higher fertility was significantly associated with female sex, higher age at assessment, being married/cohabiting, the absence of childhood neurosensory impairment, and low levels of maternal and own education.

CONCLUSIONS

VP/VLBW is not associated with lower fertility in young adults. Sex does not moderate this association. In addition to childhood neurosensory impairment, mainly sociodemographic factors (partnering, maternal and own education) are associated with fertility in VP/VLBW young adults. The evidence is limited so far to the early reproductive window in the 20 s, further follow-up into established adulthood will be required for definite answers on fertility after VP/VLBW birth.

Fertility of Adults Born Very Preterm or With Very Low Birth Weight

Importance

Contradictory differences regarding fertility among adults born very preterm (VP; <32 weeks' gestation) or with very low birth weight (VLBW; <1500 g) have been reported at different ages. Longitudinal investigations of fertility beyond ages 20 to 29 years are lacking.

Objective

To assess whether VP and VLBW are associated with lower fertility up to age 35 years.

Design, Setting, and Participants

This prospective population-based cohort study was conducted in Bavaria, Germany, with participants born between January 1985 and March 1986 who required admission to a children's hospital within the first 10 days after birth. Healthy infants born at term (ie, at least 37 weeks' gestation) in the same hospital and children alive at 6 years were selected as controls. Follow-up occurred repeatedly up to 34 to 35 years. Data were analyzed from July to December 2024.

Exposures

Gestational age and birth weight.

Main Outcomes and Measures

Cumulative incidence of having the first alive child (ie, fertility) was calculated using Kaplan-Meier estimation and the difference between participants born VP or with VLBW and term-born participants was compared with log-rank tests. Univariable and hierarchical multivariable Cox proportional hazards regressions were performed to estimate hazard ratios (HRs) for fertility associated with VP and VLBW adjusting for individual factors. Estimations were compared between early (<30 years) and late (≥30 years) reproductive windows.

Results

A total of 414 participants (212 born VP or with VLBW and 202 term-born) were included (mean [SD] age, 34.67 [0.53] years; 216 [52.2%] female). Cumulative incidence of having the first alive child was lower in participants born VP or with VLBW throughout the follow-up. The association of VP and VLBW with lower fertility was significant during the late (HR, 0.46; 95% CI, 0.31-0.68) but not early (HR, 0.73; 95% CI, 0.47-1.14) reproductive window; this association attenuated after adjusting for neonatal factors (sex and family socioeconomic status) and childhood neurosensory impairment at step 2 (HR, 0.59; 95% CI 0.40-0.88), childhood family factors (eg, parenting) at step 3 (HR, 0.61; 95% CI, 0.40-0.92), and there was no longer an association after adjusting for sociodemographic factors (eg, partnering) at step 4 (HR, 0.78; 95% CI, 0.50-1.20). Partnering (ie, being married or cohabitating with a partner) had the largest magnitude association with fertility across both the early (HR, 7.87; 95% CI, 3.44-18.00) and late (HR, 3.95; 95% CI, 2.47-6.31) reproductive windows.

Conclusions and Relevance

In this cohort study of participants born VP or with VLBW and term-born adults, VP and VLBW were associated with overall lower fertility. A major reason was an association of less partnering with lower fertility, suggesting that partnering is key to reproductive success.

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.

Association of maternal birth weight and maternal preterm birth with subsequent risk for adverse reproductive outcomes: The Women's Health Initiative

BACKGROUND

Advancements in medical technology and pharmacologic interventions have drastically improved survival of infants born preterm and low birth weight, but knowledge regarding the long-term health impacts of these individuals is limited and inconsistent.

AIM

To investigate whether an individual's birthweight or history of being born preterm increases the risk of an adverse reproductive outcome.

STUDY DESIGN

Nested case-control study within the Women's Health Initiative.

SUBJECTS

79,934 individuals who self-reported their personal birthweight category and/or preterm birth status.

OUTCOMES MEASURES

Self-reported pregnancy outcomes: subfertility, miscarriage, stillbirth, preeclampsia, gestational diabetes, gestational hypertension, preterm birth, low birthweight infant, high birthweight infant. Logistic regression models were used to estimate unadjusted and adjusted odds ratios (OR).

RESULTS

After adjustments, individuals reporting their birthweight <6lbs. were 20 % more likely to have a stillbirth or 70 % more likely to have a low birthweight infant and were less likely to have a full-term birth or high birthweight infant during their pregnancy. Individuals reporting a birthweight ≥10 lbs. were more likely to have a high birthweight infant (OR 3.49, 95 % CI 2.73-4.39) and less likely to have a low birthweight infant (OR 0.64, 95 % CI 0.47-0.82). Individuals born preterm were at increased risk for infertility, miscarriage, preeclampsia, gestational diabetes, and delivering a preterm or low birthweight infant.

CONCLUSIONS

As more individuals born preterm and/or low birthweight survive to adulthood, the incidence and prevalence of poor reproductive outcomes may increase. Women born at extremes of birthweight and prematurity may need to be monitored more closely during their own pregnancies.

Intergenerational transmission of birth weight: a systematic review and meta-analysis

The objectives of this study were (1) to systematically review the literature on the association between birth weight in children born in the first and second generation and (2) to quantify this association by performing a meta-analysis. A systematic review was carried out in six databases (PubMed, Science Direct, Web of Science, Embase, Scopus, CINAHL and LILACS), in January 2021, for studies that recorded the birth weight of parents and children. A meta-analysis using random effects to obtain a pooled effect of the difference in birth weight and the association of low birth weight (LBW) between generations was performed. Furthermore, univariable meta-regression was conducted to assess heterogeneity. Egger's tests were used to possible publication biases. Of the 9878 identified studies, seventy were read in full and twenty were included in the meta-analysis (ten prospective cohorts and ten retrospective cohorts), fourteen studies for difference in means and eleven studies for the association of LBW between generations (twenty-three estimates). Across all studies, there was no statistically significant mean difference (MD) birth weight between first and second generation (MD 19·26, 95 % CI 28·85, 67·36; P = 0·43). Overall, children of LBW parents were 69 % more likely to have LBW (pooled effect size 1·69, 95 % CI (1·46, 1·95); I2:85·8 %). No source of heterogeneity was identified among the studies and no publication bias. The average birth weight of parents does not influence the average birth weight of children; however, the proportion of LBW among the parents seems to affect the offspring's birth weight.

Adults Born Preterm: Long-Term Health Risks of Former Very Low Birth Weight Infants

BACKGROUND

Advances in neonatology now enable increasing numbers of very low birth weight neonates (<1500 g) to survive into early adulthood and beyond. What are the implications for their long-term care?

METHODS

Selective literature search on the outcome of very low birth weight neonates in adulthood ("adults born preterm").

RESULTS

Robust data are available on the pulmonary, metabolic, cardiovascular, renal, neurocognitive, sensory-visual, social-emotional, mental, reproductive, and musculoskeletal long-term risks. On the somatic level, elevated rates have been documented for asthma (odds Ratio [OR] 2.37), diabetes mellitus (OR 1.54), and chronic renal disease (hazard ratio [HR] 3.01), along with the cardiovascular and cerebrovascular sequelae of a tendency toward arterial hypertension. On the psychosocial level, the main findings are deficits in romantic partnerships (OR 0.72) and a lower reproduction rate (relative risk [RR] male/female 0.24/0.33). The affected women also have an elevated risk of preterm delivery.

CONCLUSION

A risk profile with both somatic and psychosocial aspects can be discerned for adults who were born prematurely, even if some of these risks are present in low absolute numbers. As the ability to compensate for latent deficits declines with age, such adults may suffer from "premature aging as the late price of premature birth." A holistic approach to care with personalized prevention strategies-which for most of them was discontinued at discharge from pediatric follow-up-therefore seems appropriate in adulthood as well.

Association of Preterm Birth and Low Birth Weight With Romantic Partnership, Sexual Intercourse, and Parenthood in Adulthood: A Systematic Review and Meta-analysis

IMPORTANCE

Social relationships are important determinants of well-being, health, and quality of life. There are conflicting findings regarding the association between preterm birth or low birth weight and experiences of social relationships in adulthood.

OBJECTIVE

To systematically investigate the association between preterm birth or low birth weight and social outcomes in adulthood.

DATA SOURCES

PubMed, PsycINFO, Web of Science, and Embase were searched for peer-reviewed articles published through August 5, 2018.

STUDY SELECTION

Prospective longitudinal and registry studies reporting on selected social outcomes in adults who were born preterm or with low birth weight (mean sample age ≥18 years) compared with control individuals born at term.

DATA EXTRACTION AND SYNTHESIS

The meta-analysis followed Preferred Reporting Items for Systematic Reviews and Meta-analyses (PRISMA) guidelines. The data were collected and extracted by 2 independent reviewers. Pooled analyses were based on odds ratios (ORs) with 95% confidence intervals and Hedges g, which were meta-analyzed using random-effects models.

MAIN OUTCOMES AND MEASURES

Ever being in a romantic partnership, ever having experienced sexual intercourse, parenthood, quality of romantic relationship, and peer social support.

RESULTS

Twenty-one studies were included of the 1829 articles screened. Summary data describing a maximum of 4 423 798 adult participants (179 724 preterm or low birth weight) were analyzed. Adults born preterm or with low birth weight were less likely to have ever experienced a romantic partnership (OR, 0.72; 95% CI, 0.64-0.81), to have had sexual intercourse (OR, 0.43; 95% CI, 0.31-0.61), or to have become parents (OR, 0.77; 95% CI, 0.65-0.91) than adults born full-term. A dose-response association according to degree of prematurity was found for romantic partnership and parenthood. Overall, effect sizes did not differ with age and sex. When adults born preterm or with low birth weight were in a romantic partnership or had friends, the quality of these relationships was not poorer compared with adults born full-term.

CONCLUSIONS AND RELEVANCE

These findings suggest that adults born preterm or with low birth weight are less likely to experience a romantic partnership, sexual intercourse, or to become parents. However, preterm birth or low birth weight does not seem to impair the quality of relationships with partners and friends. Lack of sexual or partner relationships might increase the risk of decreased well-being and poorer physical and mental health.