Evidence map›Paper›PMID 40680119›Full record

ArticleScience advances2025

Is sex at birth a biological coin toss? Insights from a longitudinal and GWAS analysis.

Siwen Wang, Bernard A Rosner, Hongyan Huang, Janet W Rich-Edwards, Francine Laden, Jaime E Hart, Kathryn L Penney, Jorge E Chavarro

Abstract read
PubMed Full text at PMC Publisher
In one paragraph

Article in Science advances, 2025. The graph could read no effect estimate from its abstract, so it casts no vote on the map. Cited by 2 papers.

0numbers the graph read from it
0cells of the map it votes in
2citing papers in PubMed
–field-weighted citation impact
1 · What the graph read from it

What it found

Each row is one number read from the abstract, on the scale the paper reported it, with its interval. Left of the dashed line favours the treatment, right favours the comparator. Under each row is the sentence it came from. New to these charts? A ten-minute tutorial.

The abstract states no effect estimate the extractor could read, or names no intervention and outcome on the map, so this paper lights no cell and moves no belief. It is still indexed, cited and linked below.

2 · The registry

The trial behind it

Trials whose registry record cites this paper, or whose number appears in the abstract. A trial that started after this paper was published is citing it as background, not reporting it.

Neither the registry nor the abstract names a trial number. If this is a trial report, that itself is worth knowing.

3 · Its place in the literature

Who cites it

2 citing papers in PubMed.

  1. Signatures of sex ratio distortion in humans.bioRxiv : the preprint server for biology · 2026
    Article
  2. Article
4 · The record

Corrections and comments

PubMed lists nothing against this paper. Absence here is not a guarantee, only a check that was made.

5 · Who and what money

Authors and funding

8 authors.

Siwen WangDepartment of Nutrition, Harvard T.H. Chan School of Public Health, Boston, MA, USA.ORCID 0000-0002-5605-2016
Bernard A RosnerDepartment of Biostatistics, Harvard T.H. Chan School of Public Health, Boston, MA, USA.ORCID 0000-0001-6907-0056
Hongyan HuangDepartment of Epidemiology, Harvard T.H. Chan School of Public Health, Boston, MA, USA.
Janet W Rich-EdwardsChanning Division of Network Medicine, Department of Medicine, Brigham and Women's Hospital and Harvard Medical School, Boston, MA, USA.ORCID 0000-0001-5066-8808
Francine LadenChanning Division of Network Medicine, Department of Medicine, Brigham and Women's Hospital and Harvard Medical School, Boston, MA, USA.ORCID 0000-0002-2813-2174
Jaime E HartChanning Division of Network Medicine, Department of Medicine, Brigham and Women's Hospital and Harvard Medical School, Boston, MA, USA.ORCID 0000-0002-0826-1163
Kathryn L PenneyDepartment of Epidemiology, Harvard T.H. Chan School of Public Health, Boston, MA, USA.
Jorge E ChavarroDepartment of Nutrition, Harvard T.H. Chan School of Public Health, Boston, MA, USA.ORCID 0000-0002-4436-9630

Funding

No grant is acknowledged in the PubMed record.

6 · The paper itself

Abstract

Some families consistently have offspring of only one sex, raising questions about whether sex at birth is truly random. This study investigated whether offspring sex follows a simple binomial distribution within families and identified maternal factors associated with unisexual sibships. We analyzed 58,007 US women with two or more singleton live births (146,064 pregnancies, 1956-2015). Offspring sex followed a beta-binomial rather than a simple binomial distribution, indicating that each family may have a unique probability of male or female births, akin to a weighted coin toss. Deviations from simple binomial distribution were more pronounced when we excluded each woman's last birth to reduce the influence of sex-based stopping behavior. After excluding the last birth, older maternal age at first birth was associated with higher odds of having offspring of only one sex. A genome-wide association study identified maternal SNPs linked to having female-only (

Indexed as

Genome-Wide Association StudyAdultFemaleHumansLongitudinal StudiesMaleMaternal AgePolymorphism, Single NucleotidePregnancy

Identifiers

PMID40680119
PMCPMC12273753

What Socratic holds

Textmetadata
LicenceCC BY-NC
Read underepoch 390

Registered trials

None linked

Read under generation 80e0d062 · epoch 390. Bibliography from PubMed, PubMed Central and OpenAlex; grants from NIH RePORTER; trial links from ClinicalTrials.gov; estimates, votes and beliefs from the Socratic graph.