Why can't my neighbor carry a baby past 5 months?

Hey everyone, I hope y’all are good, anyway here goes my question, there’s this female that lives in front of me but something is seriously wrong with her. She has a daughter that is now 11 years old she’s about 29yrs old (mother) but the thing is she can’t have any more children and I would really love to know why. She’ll get preg and carry d baby to term for five months, six the latest but the baby is born pre-maturely at five months and dies like a week or a couple of days later. This has happened to her for three times now. Believe me no sympathy is needed towards this female but that’s another story(she’s an evil witch) So why can’t she bring a baby to term they always come out 5 months or earlier. Some months ago she was pregnant I don’t recall how much months pregnant but, this is how she “delivered” her baby; she went to the bathroom and the fetus slid out of her vagina and she pushed it back in and shortly went to the hospital. About a month later she got pregnant again she delivered at 5months again in this month and the baby died again a couple days later. So I hope you understand what I’m saying here. Please help me, why can’t this female bring babies to term. I am a prominent Bio student and I understand that her uterus may be too thin and this is why it cannot accommodate a baby pass five months and that could account for the reason why she can’t bring babies to term but I need other opinions. Quick answers would be very very appreciated, I have been curious for some time now, please help