I like this, Daniel. I believe, traditionally, senryu have a 5, 7, 5 syllable count but I am aware that traditions change! This is 17, I think, just in a different order.
The content can be taken different ways, I suppose. Does she mean the baby is not his or that she wants an abortion? Either way, that last line provides the kick in the guts all good senryu have, whatever order the syllables are in.

Take care

I've read this a few times, and I can take the tones in a few different ways. That last line said in contempt, in resentment. That this man could never perhaps be a father emotionally and be selfless enough? But then I also read it as a couple who may be in denial about wanting a child. Who may have wanted to not have children for years and slowly, those feelings changed. Are they both on board? Is the father bitter or will he be pleased that this change, planned or not, is now something he has to either embrace or make a decision about?

Lots of thought in this one. It's a bit chilling because those words, I can only imagine, could be such a disappointment, such a cold blow to someone who has had dreams of nurturing a new life.