The study identifies a gap in the understanding of childlessness and its relationship

The gap

Evidence profile

Sourced from the stated research gap and stated challenges and future-work section and limitations and future work of the source papers, classified as general, drawn from work published between 1977 and 2026, spanning 2 journals.

Supporting evidence — 5 representative gaps

• Areal structure and rates of childlessness among American wives in 1970 (1977) · Social Biology · doi

  The study identifies a gap in the understanding of childlessness and its relationship to alternative roles and other factors that delay childbearing. The research notes that most demographic analysts of childlessness have studied older wives known to have been at risk of pregnancy and who were childless at the end of their reproductive years.

  generalstated research gap
  Keywords: study identifies gap understanding childlessness relationship alternative roles
• Age at menarche, socio‐sexual behavior, and fertility (1978) · Social Biology · doi

  The study faces challenges in measuring the complex relationships between age at menarche, fertility, and socio-sexual behavior. The research is limited by the restriction of the sample to women who have recently carried a pregnancy to term. The study must consider the factors that influence the timing of conception and socio-sexual behavior.

  generalstated challenges
  Keywords: study faces challenges measuring complex relationships between age
• Age at menarche, socio‐sexual behavior, and fertility (1978) · Social Biology · doi

  Further research is needed to understand the complex relationships between age at menarche, fertility, and socio-sexual behavior. Studies should consider the factors that influence the timing of conception and socio-sexual behavior. Research should investigate the implications of the findings for family planning and reproductive health programs.

  generalfuture-work section
  Keywords: further research needed understand complex relationships between age
• The meaning and measurement of unrealised fertility: A comparison of measures among women aged 40–49 in the United States (2026) · Vienna Yearbook of Population Research · doi

  This study is subject to several limitations. First, the four indicators developed for com- parative analysis were limited to the specific variables available within the NSFG. Conse- quently, these measures do not reflect the full range of indicators that have been used to estimate unrealised fertility. Second, the results reflect the fertility goals and outcomes of a specific cohort of U.S. women and may not be generalisable to men, gender-diverse indi- viduals or populations in different cohorts or social contexts. Nevertheless, by explicitly comparing four indicators within a single nationally representative dataset, the study results demonstrate significant heterogeneity in estimates of unrealised fertility and provide a rep- licable framework for comparative studies in other contexts. Second, the reproductive health determinants of unrealised fertility should be interpreted with caution, as infertility and pregnancy loss are often underreported in surveys (Lindberg and Scott, 2018). Similarly, as many reproductive health conditions go unrecognised or undiagnosed, knowledge of the impact of reproductive health factors on desired and achie- ved fertility is limited. The reproductive health characteristics analysed in the present study reflect those of women aged 40–49 and may not have been present earlier in the life course when most women initiate childbearing. Future surveys and novel data collection efforts (Nobles et al., 2026) that track fertility goals prospectively and document a broad range of social and reproductive health experiences would allow for a more accurate assessment of how various factors influence the achievement and revision of fertility goals.

  generallimitationsevidence 5/5
  Keywords: fertility reproductive health indicators reflect unrealised goals women four limited specific within range second social
• Reproductive disruptions in fertility research: Conceptual re-integration and evidence from Germany (2026) · Vienna Yearbook of Population Research · doi

  Our study has documented the prevalence, accumulation and age gradient of adverse reproductive experiences. Although individual findings may align with existing expec- tations, the joint analysis of adverse reproductive experiences and births provides insights that go beyond isolated event perspectives. In this final section, we outline the implications of our integrated approach and highlight promising directions for future research. Most importantly, adverse reproductive experiences should be more systemat- ically incorporated into data collections, empirical research and theory on fertility. These experiences appear today to be largely peripheral to demographic research on fertility. Infertility has received growing attention and can be seen as a forerunner in re-introduc- ing physiological and biological constraints into the study of the proximate determinants of fertility. Our findings demonstrate that extending this perspective to include miscar- riage and abortion is essential for a more complete understanding of reproductive behav- iour, particularly in contexts characterised by delayed childbearing and heightened exposure to reproductive barriers. Along these lines, our results suggest that the commonly cited notion of “fertility post- ponement” does not fully capture the range of reproductive experiences observed in age- ing societies. At the individual level, postponement typically implies deliberate timing decisions and assumes that postponed childbearing will eventually be realised. The results point to substantial heterogeneity in reproductive processes that challenges this assumption. The absence of a birth over a 10-year period does not necessarily indicate a lack of reproductive activity. Many women – and their partners – may have actively attempted to conceive but experienced only adverse reproductive events. In our sample, a notable pattern consists of childless women who reported infertility or pregnancy loss without any subsequent birth; in the oldest age group, this applies to up to one-quarter of respondents. For these women, the concept of postponement appears insufficient. Instead, their experiences are better described as forms of “fertility disruption”, as their reproductive outcomes reflect physiological and psychological barriers rather than delib- erate delay. This distinction raises important questions for future research, including about how fertility “postponers” differ from those who experience fertility disruption. https://doi.org/10.1553/p-3fdh-k3g2 24 Nadja Milewski and Jasmin Passet-Wittig Current demographic theories of fertility predominantly emphasise social, institutional and policy-related factors, such as gender equity, work-family reconciliation and family support policies, while giving comparatively limited attention to biological and health- related constraints. However, empirical evidence shows that infertility does not automati- cally translate into having fewer children than intended, which raises questions about who is able to compensate for infertility and under what conditions, and what role ART plays in this context. These questions are closely linked to micro-level processes: adverse repro- ductive experiences such as infertility or miscarriage can act as life course disruptions that affect wellbeing and shape subsequent trajectories, e.g. through union instability, altered partnership dynamics or a reduced willingness to pursue parenthood due to anticipated psychological or physical burdens. At the same time, infertility and miscarriage share many risk factors, and the use of ART may itself be intertwined with subsequent adverse reproductive experiences, and be shaped by physiological, financial, ethical, cultural or personal considerations. At the macro level, our findings highlight age as a central risk factor for the occurrence of adverse reproductive experiences and their associations with birth outcomes. While much demographic research continues to focus on policy levers aimed at facilitating child- bearing, a more systematic integration of reproductive barriers into fertility theory may help to explain why such policies often have limited effects on fertility levels in late fertility societies. Incorporating these dimensions would refine existing models of the proximate determinants of fertility and provide a more realistic account of reproductive decision-making under conditions of delayed childbearing. Further theoretical and empir- ical progress in this direction critically depends on the availability of data that capture adverse reproductive experiences. The pairfam study and recent data collections in other European countries (Beaujouan et al., 2025; Minello, 2025) demonstrate that respondents in demographic surveys are willing to report on these sensitive experiences and may even value their recognition.

  generalfuture workevidence 5/5
  Keywords: reproductive fertility experiences adverse infertility demographic physiological childbearing barriers level birth women subsequent questions individual

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