{
  "id": 7832498,
  "title": "Adaptations of the pregnant murine heart to pre-existing hypertension",
  "url": "https://urgent.news/2026/09/16/adaptations-of-the-pregnant-murine-heart-to-pre-existing-hypertension",
  "topic": "health",
  "section": "Health & Medicine",
  "published": "2026-09-16T00:00:00.000Z",
  "source": {
    "name": "bioRxiv",
    "slug": "biorxiv",
    "url": "https://www.biorxiv.org/content/10.64898/2026.09.14.751233v1?rss=1"
  },
  "original_language": "en",
  "account": "A study examined how pregnancy affects the heart of mice already experiencing high blood pressure. Among the mice, 2-5% of pregnancies are complicated by chronic hypertension which can increase the risk of heart failure and health issues for the mother [1, 2, 3]. The researchers used a mouse model to study the changes in cardiac function during pregnancy.\n\nThe researchers expected that pregnancy might help offset the negative effects of high blood pressure on the heart. Female C57Bl6/J mice, aged 7-11 weeks, were divided into three groups: pregnant mice, mice treated with angiotensin II (a hormone that causes high blood pressure), and a combination of both conditions. Angiotensin II was infused into the mice to induce hypertension.\n\nCardiac function was assessed using high-frequency ultrasound. The ejection fraction (EF), a measure of how well the heart pumps blood, remained relatively stable in pregnant mice at 65% but dropped significantly in the angiotensin II-treated group to 44.85% by day 36. However, in the mice that were both pregnant and treated with angiotensin II, the EF initially decreased but gradually improved to values similar to the pregnant mice on day 1 postpartum.\n\nLeft ventricle strain, which indicates the heart's ability to contract, was lower in the angiotensin II-treated and angiotensin II-treated pregnant mice compared to the pregnant mice. The early longitudinal diastolic strain rate, a measure of how quickly the heart relaxes, was also reduced in the angiotensin II-treated and angiotensin II-treated pregnant mice compared to baseline levels. This effect was observed from mid-pregnancy onwards, but it increased in the pregnant mice.\n\nThe researchers also looked at fibrosis, a type of scar tissue that can form in the heart. They found minimal fibrosis in all groups, suggesting that the observed changes were not due to scar tissue formation.\n\nAnother important finding was the difference in heart mass-to-body mass. Pregnant mice had the lowest heart mass relative to their body weight (6.20 mg/g), while angiotensin II-treated mice had the highest (8.95 mg/g), and the combination group had an intermediate value (6.92 mg/g).\n\nFinally, the researchers found that the size of the cardiomyocytes (heart muscle cells) was similar across all groups.\n\nIn conclusion, this study shows that pregnancy alters the heart's response to high blood pressure. These findings provide a foundation for future research that could lead to improved cardiovascular care for pregnant patients.",
  "summary": "2-5% of pregnancies are complicated by chronic hypertension [1], increasing the risk of peripartum cardiomyopathy and maternal morbidity [2, 3]. Hypertension reduces stroke volume, whereas pregnancy increases stroke volume. The combined impact of these opposing loads on cardiac function and strain remains unclear. We used a mouse model of pregnancy with pre-existing hypertension to characterize…",
  "key_points": [],
  "editors_take": null,
  "illustration": null,
  "coverage": {
    "outlets": 1,
    "also_reported_by": []
  },
  "ai_generated": true,
  "disclaimer": "Summaries, key points and the editor’s take are written by software from other outlets’ reporting and may contain errors — always check the linked original."
}