Evaluation of the relation between placental weight and placental weight to foetal weight ratio and the causes of stillbirth: a retrospective comparative study

Abstract

The aim of the present study was to evaluate the clinical importance of placental weight (PW) and placental weight to foetal weight (PW/FW) ratio according to maternal characteristics, pathological conditions in obstetrics and the causes of foetal death by category in stillbirths. The results of autopsies and placental histopathological examinations for 145 singleton stillbirths were reviewed retrospectively. Pathological features of the placenta were significantly associated with lower PW compared to the group with no pathological placental parameters (230 grams versus 295 grams, p = .045). Foetal growth restriction (FGR) with pre-eclampsia (PE) was accompanied by significantly lower FW, PW and PW/FW compared to FGR cases without PE (1045 grams versus 1405 grams, p = .026, 200 grams versus 390 grams, p = .006 and .19 versus .24, p = .037, respectively), whereas a similar trend was not observed in the non-FGR pregnancies complicated by PE. Oligohydramnios was accompanied by lower foetal weight compared to those who had normal amount of amniotic fluid (650 grams versus 1400 grams, p = .006). Among the clinical factors, only PE and oligohydramnios contributed to disproportionate fetoplacental growth in stillbirth, while none of the categories of stillbirth was related to unequal fetoplacental growth.Impact statementWhat is already known on this subject: In 27% of stillbirths, pathological features of the placenta or placental vascular bed are recorded. Underlying placental pathology contributes to foetal growth restriction (FGR) in approximately 50%. Although placental weight relative to foetal weight (PW/FW ratio) is an indicator of foetal as well as placental growth, data on PW/FW in stillbirth has not yet been published.What the results of this study add: Causes of death do not show any correlation with PW/FW ratio. Placentas derived from pregnancies complicated by pre-eclampsia (PE) and concomitant FGR are smaller and PW/FW is also diminished. Oligohydramnios is associated with an enhanced risk of restricted placental growth. FGR is not correlated with any categories of causes of death.What the implications are of these findings for clinical practice and/or further research: Sonographic follow-up of placental volume and FW can predict the stillbirth in PE complicated by FGR and oligohydramnios.