I read the urgency in your question ("I need to know") as having a few possible reasons.
One, you're somehow feeling in charge of not letting your sister get away with anything in her life. If that is it and all she is getting away with is telling the family a story that might not be true, please, ease up and let it go. As specialmom says, it means a person is in emotional straits if they lie about something this serious, and it won't help to have you in there judging and disproving. Not only won't it help her, it degrades you.
Another possibility, you're genuinely worried about her mental health and are thinking of taking some active step if you think she has lied. If the step is positive, and you care that much about her well-being, go to Alaska and see if you can be of help to her. Don't go there to run her life, go to see if she needs assistance. (I can promise that if you walk in judgmental, you will not help her and she will not tell you much.)
Another possibility would be that you're worried about some guy she might have been snookering with this story (if she is lying, which you have no proof of, since her story is medically plausible). If you're not worried about your sister and are worried about the guy, sheez, back away. It is not your lookout (no matter whether you have a hidden agenda about the guy or not) to save some guy. If she is trying to keep someone attached by making up this story, he has probably sniffed it out already.
Another possibility is that you're worried because she is getting money from the family, you or your parents?, by telling this story. Can they not afford it? Can you not? If that is the case, you need to be frank with her about what you can and can't pay for, and so do your parents. If they won't, it is not your problem. Sorry to say, but we can't control our parents. lol
Along with the other ladies, I would be interested to know why this matters so urgently to you.
I lost my baby at 19 weeks back in 2009. I was devastated. Heartbroken. And still grief at times. My two options were to have the baby removed (which they put you to sleep and remove the baby) or let your baby come out when it's ready and deliver it and be able to see the baby and what not. I chose to remove the baby immediately because I knew I wouldn't be able to handle seeing my baby gone.
But what makes you not trust or doubt in her she wasn't pregnant?
I'm just burning with curiosity about why you think she would fake this - and wonder if the two of you have always had a deep rivalry that would make you jealous of attention your sister receives from family.
My other thought is, if you're right and your hunch is correct and you have reason to believe she faked this pregnancy and miscarriage - your sister is dangerous. Women who fake a pregnancy and miscarriage - whether to get attention, or make an ex-boyfriend crazy, or because they have an extremely unhealthy obsession with pregnancy - are dangerous.
But I agree with the others - you can't tell one way or the other by vetting her story she told you. Miscarriage at that stage of pregnancy happens in a huge variety of different ways from home still birth with no hospitalization to lengthy hospitalization that was geared to saving the pregnancy.
I'd be curious to know more.
Here's what I would do--- either way, your sister needs empathy. Some women have their water break and actually deliver the baby at that stage of pregnancy and they are not kept in the hospital. It's very sad. Some choose to see their baby and some don't. So, perhaps she went through this which is very traumatic for women. Or she didn't, in which case she is in emotional distress to make this up. Either way, show her kindness and tenderness. You can recommend some counseling to her as you can tell her that you are sure she is sad to have lost her baby and then she will be seeing a professional either way to try to help her. But be gentle with her. peace
My question for you is why are you doubting her story?
Nobody here can tell you if she lost a baby or not; only she knows that.
It is not impossible to lose a baby at 5 or 6 months, and the medical procedure for care of the situation is different for different women and stillbirths, depending on what happened. If she is lying about having been pregnant, you are going to have to find out another way besides trying to knock down her story.