Miscarriages Not Caused by Chromosome Errors

The vast majority of miscarriages are caused by chromosomal errors in the embryo. But not all of them are. There are a wide variety of theories and speculations about the various causes of miscarriage other than chromosomal abnormalities, with a great deal of far-ranging debate. The fact that eggs from young women transferred into older women result in a high pregnancy rate and a low miscarriage rate makes it fairly clear that the major problem is with the aging ovary. However, less commonly there are problems other than the aging ovary (or intrinsic genetic problems with the eggs) related either to the woman herself, or to the uterine environment into which the embryo is placed.

Several years ago, a young woman in her late twenties with a puzzling problem was referred to us by her employer. She already had one child and readily became pregnant four times after the birth of that first child, but each of those pregnancies ended in miscarriage within the first three months. This woman had no difficulty whatsoever getting pregnant, but she suffered from recurrent miscarriages only after the birth of her first, healthy child. Because her local doctors had failed to give her an adequate answer, I assumed this would be a very difficult case requiring PGD to determine the chromosomal constitution of her embryos. We planned IVF with PGD, but first we took a routine X-ray of her uterus to make sure that it was normal. For fertility specialists, this is a simple, routine request, almost like a blood count, urinalysis, or Pap smear in the yearly physical exam. We simply wouldn’t do IVF without being certain the uterus is normal. When we performed a hysterosalpingogram (HSG), we found that the upper and lower walls of the uterus were stuck to each other, forming a so-called pillar. This had to have been caused by retained placental fragments during the delivery of the woman’s first baby five years earlier. She had gone through all these miscarriages over the last five years with no chromosomal evaluation of her miscarriage (which is a common oversight), but also no evaluation of her uterus. With a relatively simple hysteroscopic operation to separate the scarred adhesions between the top wall and the bottom wall of her uterus, she became pregnant very quickly on her own, with no need for IVF, and had a healthy delivery.