The mechanism by which the embryo signals its presence in the womb, and how the embryo implants into the uterine lining is not fully understood. In 1907, a German doctor called Dr. Loeb, described an experiment in guinea pigs in which he had observed that after sexual activity ‘nodes’ (knoten) developed in response to injury artificially made in the uterine lining.
Following this observation, a team in Israel in 2003, described an experiment that improved implantation rates in humans after a similar ‘injury.’ The Israeli research team followed 134 patients who had previously failed to get pregnant after a routine embryo transfer. Forty-five patients were randomly selected and at four separate out-patient appointments during the menstrual cycle before an IVF treatment were given an endometrial biopsy, a widely used investigation in infertility tests. Most of these women had already failed four or more previous IVF treatments.
Thirty of the women who underwent the biopsy (67 percent) conceived compared with 27 out of 89 (30 percent) in his untreated control group.
However, in 2014, a team in Hong Kong published a randomised controlled trial that produced very different findings. They followed 300 patients, of whom two-thirds had not had a previous IVF cycle. Half the patients were sent for an endometrial biopsy on day 21 of the preceding menstrual cycle, and 150 had no treatment. Only 26 percent of the patients who had a biopsy delivered a live birth, whilst 32 percent in the untreated group had a baby. So it seems that the early promise of the endometrial scratch remains questionable.
One doctor studied this in detail and her view was that the uterus may be more receptive to the embryo after injury because of the inflammation that results. There is an influx of white blood cells (in particular macrophages and dendritic cells) to the affected area of the uterus, and these cells then stimulate the production of chemicals that improve the messages between the embryo and uterine lining.
Dendritic cells are part of the ‘white’ cell system in the blood. They have a very folded surface which helps them to attach to antigens which are then tackled and neutralised by other cells in our immune system. They are called dendritic because at certain stages of their development they grow fine branches (dendrites) a bit like a tree.
Despite countless breakthroughs in medical science, we still do not understand why some pregnancies will end in tragedy. For most of us, having a child of our own is the most fulfilling experience of our lives. All of us can imagine the desperation and sadness of parents who lose a baby, and the life-shattering impact that a disabled or seriously ill child has on a family.
Professor Robert Winston’s Genesis Research Trust raises money for the largest UK-based collection of scientists and clinicians who are researching the causes and cures for conditions that affect the health of women and babies.
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