Velum interpositum

https://radiopaedia.org/articles/velum-interpositum

The velum interpositum is a small membrane containing a potential space just above and anterior to the pineal gland which can become enlarged to form a cavum velum interpositum.

Gross anatomy
The velum interpositum is formed by an invagination of pia mater forming a triangular membrane the apex of which points anteriorly.

Boundaries
superiorly: the columns of the fornices and hippocampal commissure (psalterium) reaching as far forward as the foramen of Monro
inferiorly: the internal cerebral veins and tela choroidea of the third ventricle
inferolaterally: the thalamus
posteriorly: the narrow base of the triangle abuts the splenium of the corpus callosum 1

It varies in shape from persion to person, sometimes interposed between the internal cerebral veins and splenium, and depending on whether or not there is a cavum vergae (in which case the columns of the fornices are displaced inferiorly, narrowing the velum interpositum).

When somewhat distended by fluid it forms a small triangular (in axial section) space and is referred to as a cavum velum interpositum. If larger and exterting mass effect it is known as a cavum velum interpositum cyst.

Normal values for serum albumin in pregnancy

http://perinatology.com/Reference/Reference%20Ranges/Albumin.htm

https://academic.oup.com/tropej/article/28/4/193/1695011

https://www.ncbi.nlm.nih.gov/pubmed/7507040
Early Hum Dev. 1993 Oct;34(3):209-15.
Albumin levels in pregnancy: a hypothesis--decreased levels of albumin are related to increased levels of alpha-fetoprotein.

Maher JE1, Goldenberg RL, Tamura T, Cliver SP, Hoffman HJ, Davis RO, Boots L.
Department of Obstetrics and Gynecology, University of Alabama at Birmingham 35233-7333.

Abstract
Serum albumin levels decrease during pregnancy while the concentration of most other maternal serum proteins of hepatic origin remain stable or increase. In a study of 289 women, most maternal characteristics such as race, age, smoking, a history of previous low birth-weight, infant sex and gestational age at delivery were not related to maternal serum albumin levels at 18 or 30 weeks' gestational age. The degree of maternal obesity significantly correlated with the concentration of albumin. There was a significant negative correlation in individual women between maternal serum levels of albumin and alpha-fetoprotein, with high levels of maternal serum alpha-fetoprotein predicting lower levels of albumin. We hypothesize that there may be a negative feedback effect of alpha-fetoprotein of fetal origin on the maternal production of albumin during pregnancy.
PMID: 7507040