I think the whole WFH has always been seen as an open door to do as little as possible by a lot of people. And not just during Covid.
That said, you need hard facts about what she's not doing before taking it any further if that's what you intend to do.
How does it seem she's not doing anything?
Is it a project where there's a quantifiable outcome? (Can you see that you, for example, do 75 tasks and she does 25)
Are hours logged?
When you say meetings- who is present?
Is her active participation in meetings a usual requirement? (I'm a teacher and we've had lots of staff/class teacher meetings- in some I talk, in some I don't, depends if there's anything relevant I need to say)
How long do the meetings last? Would she be expected to not leave her desk for a few seconds/minutes/ during a normal working day? How often are the meetings held? Is a
Iine manager present?
When you speak to someone focus on yourself and the fact you are having difficulty meeting the requirements on the joint (stress that) project because of the colleague's situation.
She probably shouldn't be working, but you can't mention that because she's legally and contractually able to.
She might be swinging the leg, she might be trying her hardest to work with a baby in the house. Because you don't know, you can only really talk about the factual things above and how the work is impacted.