I'm 42 nearly 43 having my
5th. All same dad. There will be almost 12 years between my eldest and youngest. I fell pregnant naturally. I'm 38 weeks and no abnormalities have been identified.
In your position I don't think I would go through ivf but i wouldn't take active steps to prevent it either - if it happens, it happens surely. If you haven't gone through the menopause then your body is still capable of carrying a child. Yes you are more at risk of eg downs but you will also be screened and it is still generally a low risk. As your partner is younger this decreases the risk too. I have been researching my family tree recently and less than 100 years ago women were often having children well into their late 40's.
I think a lot depends on the demographic you live in. With my first (who I had at almost 31) I was definitely one of the younger mums when my daughter started in reception. She's privately educated now in secondary school and I am much (a decade) younger than most of her school friend's mums (although there are some my age too). One of my other children is in reception this year and there are plenty of mums that are more than 5 years older than me - but we live in an area where house prices are excessive so often it's older couples that can afford them. I won't feel different in our community but I can imagine if you live somewhere that people are adamant that after 32 is too old that you might feel awkward or a bit lonely. You'll also be so busy that you won't have time to think about it though!!
To be honest if you want and can afford a 5th child it is no ones business other than you and your partner (and to an extent your other children). Your partners wishes are very important in this sort of decision.
It's pointless asking on a forum such as this as you will just get people saying they think you are too old and that you are going to leave your child motherless and you will be too old to play with your child (wtf, generally coming from people happy to leave their children with their 60 something parents for free childcare).
Ironically my mum had me at 42 too. Her only child. She looked after my first born for me when I went back to work (she was nearly 73), driving, spritely and interesting. She potty trained her for me at just 2 and taught her to read and write. She did much more with my daughter (and had a closer bond) than my husbands mother ever did
despite her still being in her mid 50's when my daughter was born.
She was a brilliant mum to me too. Unfortunately she died last year, but I'm not the only 40 something that has lost their mother and she was firmly around for me well into adulthood.
Some people would be too old (either physically or mentally) to have a baby past 40. Others aren't.