{
  "abstract": "Background\n\nAn increasing number of pregnant women, including elite athletes, continue vigorous- and high-intensity exercise during pregnancy. Current pregnancy exercise guidelines primarily recommend at least 150 min of moderate-intensity physical activity per week and provide limited specific guidance on vigorous- and high-intensity exercise in highly trained pregnant women. High-intensity exercise can elevate core temperature (Tcore), raising concerns about maternal hyperthermia and potential fetal risks (e.g. neural tube defects, preterm birth, fetal growth restriction). Accurate monitoring of maternal Tcore may be necessary to evaluate safety. However, pregnancy-related cardiovascular and thermoregulatory adaptations, such as changes in skin blood flow and heat dissipation, may affect temperature estimates, yet few non-invasive and user-friendly methods combine accuracy with practicality during exercise. This study compared the non-invasive CALERA Research Sensor (CRS) with a rectal probe, the gold standard for Tcore measurement, during high-intensity interval running in pregnant and non-pregnant participants.Methods\n\nThirty elite and recreational athletes participated, including 15 pregnant participants (31 ± 4 years) and 15 non-pregnant participants (30 ± 6 years). All completed a separate 10-min warm-up, followed by up to five 5-min high-intensity treadmill-intervals separated by recovery periods. Testing was conducted under environmental conditions of 20-21°C and 38-61% relative humidity. Analyses included the intervals, corresponding pauses, and 20 min of post-exercise, during which no cool-down was performed. Agreement was assessed using Bland-Altman plots, with a pre-defined ±0.3°C acceptability threshold. Differences were analyzed using paired t-test.Results\n\nNearly half of the measurements exceeded the predefined threshold (47% in pregnant vs. 43% in non-pregnant participants), reflecting systematic bias between methods. In pregnant participants, the mean difference (rectal probe - CRS) was -0.23°C (95% CI: -0.36, -0.09°C), indicating that CRS overestimated Tcore relative to the rectal probe. In contrast, in non-pregnant participants, the mean difference was 0.16°C (95% CI: 0.03, 0.28°C), indicating that CRS underestimated Tcore. Discrepancies were most pronounced during the early intervals but diminished over time.Conclusion\n\nThis study shows opposing systematic bias of CRS in pregnant and non-pregnant women compared with Tcore measured using a rectal probe, limiting its use as a stand-alone tool in pregnancy and highlighting the need for non-invasive temperature sensor development.",
  "abstract_shown": true,
  "affiliations": [
    "Department of Sports Medicine, Norwegian School of Sports Sciences, Norway.",
    "Medical Service Institute, Norwegian Armed Forces, Norway."
  ],
  "article_type": "research article",
  "arxiv": null,
  "author_total": 5,
  "authors": [
    {
      "affs": [
        0
      ],
      "name": "Sofia Brevik-Persson"
    },
    {
      "affs": [
        1
      ],
      "name": "Jørgen Melau"
    },
    {
      "affs": [
        0
      ],
      "name": "Emilie Mass Dalhaug"
    },
    {
      "affs": [
        0
      ],
      "name": "Christina Gjestvang"
    },
    {
      "affs": [
        0
      ],
      "name": "Lene A H Haakstad"
    }
  ],
  "bibtex": "https://research.draconitic.com/paper/69h0n0sff0jyh.bib",
  "cited_by": 0,
  "doi": "10.1016/j.jesf.2026.200529",
  "fulltext_url": "https://europepmc.org/articles/PMC13693318",
  "id": "69h0n0sff0jyh",
  "issns": [
    "1728-869X",
    "2226-5104"
  ],
  "landing_url": "https://europepmc.org/article/MED/42921436",
  "language": "eng",
  "licence": "CC-BY",
  "licence_label": "CC BY",
  "licence_source": "article",
  "licence_url": "https://creativecommons.org/licenses/by/4.0/",
  "metadata_licence": null,
  "native_subjects": [
    [
      "openalex",
      "2737|Thermoregulation and physiological responses"
    ]
  ],
  "openalex": "W7215119817",
  "pdf_url": "https://europepmc.org/articles/PMC13693318?pdf=render",
  "pmcid": "PMC13693318",
  "pmid": "42921436",
  "published": "2026-10-01",
  "publisher": null,
  "ris": "https://research.draconitic.com/paper/69h0n0sff0jyh.ris",
  "sources": [
    {
      "first_seen": "2026-10-30T12:20:36Z",
      "native_id": "MED:42921436",
      "source": "europepmc",
      "url": "https://europepmc.org/article/MED/42921436"
    }
  ],
  "subjects": [
    {
      "field": "medicine",
      "origin": "openalex:2737|Thermoregulation and physiological responses",
      "subfield": "physiology"
    }
  ],
  "title": "Comparison of a wearable core temperature sensor with rectal thermometry during high-intensity interval running in pregnant and non-pregnant women.",
  "title_text": "Comparison of a wearable core temperature sensor with rectal thermometry during high-intensity interval running in pregnant and non-pregnant women.",
  "type": "peer-reviewed",
  "updated_at": "2026-10-30T12:20:36Z",
  "url": "https://research.draconitic.com/paper/69h0n0sff0jyh",
  "venue": "Journal of exercise science and fitness",
  "versions": []
}