I'm watching this right now

I have seen other versions. I am very confused as to the segment where she is at the opera sitting and chatting with countesses and she comes out of the box, runs into Vronsky, tells him to take her away, he says he will in about a month after he is discharged. Then she faints dead away in his arms.

The very next scene is when Ralph Richardson gets a telegram from her saying she is dying and wants his forgiveness. He shows up and is told 'The child is stillborn and it doesn't look good for her".

Whe the hell was she pregnant? I never saw a jump in a storyline quite like that.

Anyone else understand where I'm coming from. I mean, she faints in his arms (not looking pregnant), and two minutes later she gives birth????