Small placentas were more common among stillbirths in an observational study

Findings

The researchers weighed and measured 390 fresh, trimmed placentas from stillbirths. Causes of death were categorized with the 2018 Perinatal Society of Australia and New Zealand Perinatal Death Classification system. A statistical model was used to assess how the likelihood of a small placenta varied with potential explanatory factors.

According to the abstract, small placentas were seven times more common in this stillbirth cohort than among livebirths. Within the stillbirth cohort, babies stillborn at term were more likely than those stillborn preterm to have a small placenta (relative risk 1.7; 95% confidence interval 1.1–2.4) and a low placental-weight-to-birthweight ratio (relative risk 2.7; 95% CI 1.7–4.2).

Of the 390 stillbirths, 117, or 30%, were classified as unexplained. The researchers reported an association between unexplained stillbirth and small placental size, with an adjusted relative risk of 1.6 (95% CI 1.1–2.2). Peripheral cord insertion was associated with a 20% greater likelihood of a small placenta (adjusted relative risk 1.2; 95% CI 1.0–1.3).

Why it matters

The study identifies a pattern linking small placental measurements with stillbirth, including cases that remained unexplained under the classification system used. The reported differences were also greater for term than preterm stillbirths. These observations help characterize the placental features present in this cohort, but the abstract does not demonstrate predictive, preventive or diagnostic value.

What remains uncertain

This was an observational analysis, so it cannot show that a small placenta, low placental weight or peripheral cord insertion caused stillbirth. The abstract does not describe the livebirth comparison group, thresholds defining a small placenta, study setting, participant characteristics, adjustment variables or absolute risks. Consequently, possible bias, generalizability and clinical usefulness cannot be fully assessed. The supplied source is a journal record, but its peer-review status is not verified.