Where does “transplacentary” come from?

transplacentary (English) comes from English placentary, from English placenta, from New Latin placenta uterina, from Latin placenta, from Ancient Greek πλακόεντα, from Ancient Greek πλακοῦς, from Ancient Greek πλακόεις, from Ancient Greek πλάξ — flat.

Ancestry of “transplacentary”, step by step

transplacentary traces back through two separate lines of ancestry.

via English placentary

StepLanguageWordMeaning
1EnglishplacentaryRelating to the placenta; The projecting line or...
2EnglishplacentaA vascular organ in mammals, except monotremes...
3New Latinplacenta uterinauterine cake
4Latinplacentaa round phyllo cake with a ribbed base and a...
5Ancient Greekπλακόεντα
6Ancient Greekπλακοῦςflat cake
7Ancient Greekπλακόειςflat
8Ancient Greekπλάξanything flat and broad
9Proto-Hellenicpləks
10Proto-Indo-Europeanpleh₂-flat

via English trans

StepLanguageWordMeaning
1EnglishtransIn a double bond in which the greater radical on...
2EnglishtransgenderHaving a gender which is different from the sex...
3Englishgenderkind
4Middle Englishgender
5Middle Frenchgendre
6Latingenusbirth, origin, lineage, descent; kind, type,...
7Proto-Italicgenoslineage, origin
8Proto-Indo-Europeanǵénh₁osrace, lineage
9Proto-Indo-Europeanǵenh₁-to produce, to beget, to give birth
Every word from Proto-Indo-European pleh₂-