Will another baby ruin our life?

What’s your concern with generic testing?

About DD being a big sister and having family when you're gone, could you do something to nurture sibling-like relationships for her? If she has cousins, make an effort to help them spend time together, or do the same with your friends' DC or other only child families you're close to.

I don't think you should feel guilty about your DD being lonely/lacking family as an only child, but it's a good reason to put extra effort into ensuring she has more potential lifelong ties as an alternative to siblings. My parents were very introverted and I feel I missed out in a way as we didn't spend much time at all with my cousins or other families, and they didn't socialise much so I didn't grow up alongside family friends.

I've name changed for this just in case.

My almost 3 year old daughter has a physical disability (spina bifida). She was also an IVF baby born after multiple attempts, 3 miscarriages (one in the second trimester due to an infection). In our case the disability doesn't seem to be genetic - amniocentesis revealed nothing - and they have no idea why she was affected. I do have a higher risk of having a second child with a disability but nobody really knows how much higher since they don't actually know what happened the first time round.
We're about to start trying for number 2 using the embryos we still have frozen.and we've actually decided against genetic testing of the existing embryos because the risk of a perfectly good embryo being damaged during defrosting, testing or refreezing. Since our daughter's disability isn't genetic the chances of them finding something are no higher than for anyone else with our background (age, etc.). The cause of my infertility was eventually determined to be adenomyosis so our daughter's disability isn't related to that either.

The reason we've decided to go for a second child because we both really want one. Even before our daughter was actually born we started talking about the possibility of having a sibling for her one day, under which circumstances we would decide against it, etc. I do think our daughter would be an amazing big sister but as an oldest child with a younger sister who doesn't really bother with me that would never be a reason to have a second child (although I do hope my children will end up closer than my siblings and I).
While my daughter does require more work than a child without a disability it's (currently) manageable and I'm not really worried about a second child fitting in around her appointments. At first the baby can just come along and by the time they're a toddler they'll either be in nursery or my daughter will be old enough to just be dropped off for her appointment while sibling and I wait outside. I'm more worried about how things will work during pregnancy since my daughter (currently) can't walk and I have to lift and carry her a lot. She's due to get a wheelchair soon though - actually it was supposed to already be here - and by the time we can actually start the IVF process she should be able to use it independently so that would definitely make things easier.
Cognitively our daughter is absolutely fine. She's actually ahead of her age for speech/language! Fine motor skills are where they should be. Right now her only issues are 1) she can't walk - but can crawl and get around independently in other ways, and is working hard on standing. Her doctors and physiotherapist are relatively certain that walking will happen for her one day - and 2) she's still in nappies and may not ever be "toilet trained" in the traditional sense since we're currently unsure whether she can even control her bowels. I don't think either of those things would be detrimental to a sibling. However, all of this is assuming we end up with a healthy second child. Honestly, if I was told the chances of having a (potentially even more significantly) disabled child next time round were as high as 50 percent my decision would probably have been different. At the very least we would definitely be genetically testing the embryos despite the risks!

It doesn't sounds like you're making the decision out of fear. From your post I get the impression you're not having another child out of mature considerations for the negative impact it could have on your family in it's current configuration.

I don't know what's the genetic condition affecting your DD, but often parents carrying a recessive/mutating gene, means nothing to their health. They'll have normal lives without being affected at all.

Often, the problem arises when 2 parents carry the same recessive gene have 50% chance of that gene being dominant in their child. I'm surprised that if your DD has a genetic condition, the NHS did not refer you to a children's genetic clinic so as parents, you understood the gene and everything that's known about it.

Life is not fair, OP. You have a wonderful daughter that one day will be able to live an independent life. She may need a kidney, this is why kidney transplants waiting lists are for, even both you are not compatible. To put your mind at ease a bit more on this issue, it's extremely unlikely that your DH or you (as her parents), won't be compatible to give her a live transplant when she needs it.

@GingerPirate sound advice, exactly what she needs

Until you know it’s not you isn’t it hanging over you anyway? If it is you it might be good to have time to make peace with it.

If you could get comfortable with it I think embryo screening as suggested by PPs would be my first choice in your position.

Why would you have another child when there is a strong possibility you will again be passing on a disability. That would be incredibly selfish.

What if you ended up with twins?

I don't think you'd be giving into fear if you chose to not have another. I think you'd be making a very wise choice and one that would probably be best for your daughter, you and your husband.

Is your daughter happy, loved? If that's your measure of a perfect family then go for it - disability is not the be all and end all.

In your situation OP I wouldn’t, for all the reasons others have said plus the fact you’ve now said whoever has this gene will have symptoms “at some point”. That could be anytime I presume, so what if you had another child who had more severe disabilities and then either you/your partner begins to decline?

It is really tough. I was in a similarish situation to you after having our first DC. I couldn't have gone through with a termination for the condition in question, but I felt just about ok with screening via IVF. In the end we had a second DC via egg donor - I always knew it was me who carried the gene mutation. We are thrilled with our second child and are so glad we've had them. The main downside for us was that going via the IVF route took a long time. For me, it's been important to take ownership of my / our choices, and I'd encourage you to do the same, hard as it is.

Additionally, is there certainty that the mutation comes from you or DH, or could it be de novo in your DC? I don't know how it's possible to know the answer to this without you and your DH both being tested for the mutation, but I'm not an expert.

WTF???

Honestly,, no.

It took us a while after DSs traumatic birth to try again and that was without any other issues with the delivery, pregnancy etc. Thankfully his condition is a random genetic mutation so there was no risk in future pregnancies.

If there had been a 50% chance of it happening again and a 33% chance of it being worse (thinking if she's mid range then one third around her level of severity, one third above etc). AND knowing that we couldn't have done all we did for a future baby as we had for our eldest, I couldn't do it.

You can't rationalize intentionally giving one child a better chance of dealing with their disability than the other imo.

Enjoy your gorgeous girl and throw everything into her. Build up networks and an pseudo family around her.

When you are really struggling to make a decision, make it based on the assumption that the worst case scenario WILL happen.

In your case you have a pretty high chance of a not so rosy outcome.

Picture the worst case scenario OP. If it makes you feel real dread don't risk it.

I agree with this. If your second child has a severe disability then you're in for a seriously hard ride, being the parent of 2 children with disabilities, and possibly one being severe, can destroy lives.

Also, siblings often don't get on. If you have a second child, have it because you enjoy it and are looking forward to playing with a second baby / child all over again.

I wish i was an only! desperately wanted a sibling as a kid, unfortunately they were a HUGE disappointment, we fought all the time and as adults we barely speak. Dreading having to sort out my parents estate when the time comes.

Enjoy the dd you have, as an only she gets all your time and attention and IMO that is priceless! Much better than a crappy sibling.

Is there a reason why you haven't found out which of you is carrying the gene? In your case, I would be inclined to find that out and then if I wanted another child go ahead with either a sperm or an egg donor.

I’ve been through a very similar and painful decision process. DS is disabled, his older brother was still born after early rupture of membranes, they were both conceived through IVF.
I had preeclampsia in the late stages of pregnancy and was close to having a stroke, DS was delivered vaginally but with forceps which caused major internal trauma and meant a long recovery.
Despite ALL of this and all of the risks I still wanted another child, DH just couldn’t understand and in the end made an emotional plea that he just couldn’t do it - he couldn’t watch another child die or potentially watch me die. That was what I needed to hear to be able to agree with him. He had a vasectomy last week.
I think I’ve made my peace with it now and DS is a joy, and hard work!
I think your DH needs to contribute to this decision, it seems unfair of him to leave it to you, he must have fears or concerns of his own?