I'd be narked too - but tell her you will arrange for a freelance to sort the horses for the period she's away and she can pay half.
Your husband (if not horsy) will be more focused (and rightly so) on you when the baby is being born and might miss something (cuts/lost shoes etc) whilst distracted.

Your friend has been kind to offer to help you during your pregnancy and when you have a newborn. From what you have said, I would imagine that her help with your horse will be over quite a period of time (during the last trimester when you are quite large and first trimester when you are post partum - so a good few months in total) Compared to that, she will need your help for around 2 weeks, assuming that her holiday is that long. Of course it's a bit inconvenient that she's going when you are due but she's entitled to pick when is right for her. She's even giving you considerable notice so I don't think you should be feeling narked really. It sounds like you have both got plenty of time to figure out an option that works - whether that is getting your other half up to speed with what he needs to do to look after both horses or getting a freelance groom in to do them both. Congrats on your pregnancy too :-)

YAB a bit U, I think. I can understand you feeling narked about the timing, but it sounds as though it is really worth maintaining friendly relationships with her as it's so so worthwhile having someone who will happily do your horses if needed and it's really really dreadful field sharing with someone where the relationship has broken down. Even if there is a minor lingering tension or gripe it can be annoying. You don't really want to get yourselves into a position where one of you can 'veto' holidays or days away etc. for the other because it isn't convenient for you so I think you have to accept it's her right to go away and be unable to look after the horses (providing she gives you notice), just as it's your right to have time with the new baby.

So I'd be very very cautious of implying she's done anything wrong here - there may be all sorts of factors that affect when she can take her holiday meaning she can only go then, or perhaps you and your horse are just low down her priority list - neither make her a bad person, maybe just a bit thoughtless. I can see the situation cropping up lots over the next few years though e.g. she's stuck at work, you have a sick baby etc., who has to go and deal with horses? I think you need to find an amicable way of resolving these kind of things or resentment will start to creep in.

I think my solution probably would be to identify a local freelance groom or pet-sitter with horsey experience or even a competent local horsey teenager who can be booked to see to the horses once or twice a day for a fee, and see if she'll agree to split the cost between the 2 of you? I think this would be safer and better for the horses than your non horsey DH doing it as someone experienced will know better than him what to do if there's an injury or field escape or even things like a broken rug or fencing etc. - also as you are due right around the dates of the holiday you need contingency for if you are actually in labour/hospital when she's away, as presumably you won't want your DH leaving to go feed the horses. If you find a good reliable person the arrangement can be that they are booked and costs split anytime you are both away or unavailable. Then keep your DH in reserve as more of an 'emergency' callout option... would this work?

I agree that getting in a freelance to cover those two weeks would make sense. It would be good to have the option of someone else to look after the horses in future anyway as this won’t be the only time that neither of you will be able to do so. And yes, I do think you’re being a bit unreasonable - it’s not like she’s sprung this on you at the last minute, she’s giving you several months notice so the two of you have plenty of time to sort out a solution together

Freelance groom definitely! I can see why you're a bit peeved, but she's done nothing wrong.

She's given you 4 months + notice. Her life can't revolve around your pregnancy. I don't think my DP would be that understanding if we managed to sort out our ideal holiday and I refused to book it because I was looking after a friend's horse. If I were being paid as a freelance groom and it was a work commitment it would be different. If she'd dropped you in it 2 weeks before it would be different.

Go halves on a freelance groom. You'll want someone reliable who the horses know for future reference anyway and this gives you time to find someone good before your friend goes away.

She’s only away for a week or two. She’ll be helping you for perhaps a month or two. You’ll be getting more back than she gets from the arrangement so it’s fine. A local freelancer sounds ideal. Speak with her about it and see what she suggests. Perhaps she thought your hubby would drive you up and you could supervise from the car as both horses are easy so it shouldn’t be too bad.