I thought I understood this but as I look at it I can't quite untangle the grammatical relation between the words: I parse each word and offer a translation below. My real problem is the words 'partu' and 'ediderat' both of which can mean 'give birth'.
[Ovidius: Fasti. Ex libro II]
Silvia [FNS] Vestalis [FNS] caelestia [Adj. NAP] semina [NAP] partu [SUP]
Vestal Silvia had borene divine children
ediderat [Plp3S], patruo [MabS.] regna [NAP] tenente [MAb.S (participium)] suo [MAb.S].
her uncle keeping holding the kingdom
I'm relying on 'ediderat' to tell me what she had done. What's the supine 'partu' doing here?