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Trial Lecture – time and place
See Trial Lecture.
Adjudication committee
- First opponent: Professor Ulrik Schiøler Kesmodel, Aalborg University, Denmark
- Second opponent: Associate professor Ingrid Petrikke Olsen, The Arctic University of Norway, UiT,
- Third member and chair of the evaluation committee: Professor Anne Flem Jacobsen, University of Oslo
Chair of the Defence
Professor Ole Morten Rønning, University of Oslo
Principal Supervisor
Senior Consultant Vigdis Hillestad, Akershus University Hospital
Summary
This thesis is written by Helene Fjeldvik Peterson and colleges, within the fields of Obstetrics and Gynecology, focusing on the placenta during pregnancy.
Abnormal placental weight after delivery is associated with negative outcomes for the child, such as neonatal death, low Apgar scores, and cerebral palsy. However, delivered placentas may not be the same as placentas in ongoing pregnancies.
The aim of this thesis was to describe placental growth and its relation to fetal growth (ratio), to compare intrauterine placental size with placental size at delivery, and to study the correlation between placental size and ratio with subsequent fetal growth.
We used data from the Placental Volume (PLAVO) Study, which measured placental and fetal volumes by MRI in singleton pregnancies at gestational week (GW) 27 (n=104) and at GW 37 (n=89). For comparative analysis, we used data on births at GW 36 from the Medical Birth Registry of Norway (2016–2019).
We found a wide range of placental volumes, and placental growth being less pronounced than fetal growth from GW 27 to 37. Percentile curves for placental growth and ratio were published. The comparison with deliveries suggested that the placenta during pregnancy is significantly larger than after delivery, particularly in vaginal births after spontaneous onset of labor. The ratio was also higher in ongoing pregnancies.
A positive correlation was found between placental volume and ratio at GW 27 with average fetal growth velocity from GW 27 to 37. Smaller fetuses exhibited a significantly lower growth velocity if they had a smaller placenta.
We provide normative data for intrauterine placental size and ratio, which is a prerequisite for diagnosing abnormal placental size. Data from delivered placentas cannot be used when evaluating the intrauterine placenta. Measurement of placental size may aid in the evaluation of fetal wellbeing, since placental size is correlated with subsequent fetal growth, especially among small fetuses.
Additional information
Contact the research support staff.