July 1, 2003 — If a woman's first child is a boy, she runs a risk of suffering chronic miscarriages in subsequent pregnancies, a Danish fertility expert says.
Ole Christiansen, a consultant registrar at Copenhagen's Rigshospitalet Fertility Clinic, assessed 204 women who had suffered from serial miscarriage, a term defined as at least three repeated miscarriages after a first pregnancy that lasted more than 20 weeks.
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Only 54.4 percent those who gave birth to a boy in their first pregnancy had given birth to a second live baby by the end of the study in January 2002, compared with 73 percent of women whose first child was a girl.
Amongst those women who did manage to have a second child after a series of miscarriages, those whose first child was a boy had an average of 3.9 miscarriages before achieving a second birth.
But women whose first child was girl had 3.5 miscarriages before delivery of a second child, a statistically significant difference.
In addition, the average birthweights of the second children tended to be 181g (six ounces) higher in cases where the first-born was a girl.
Christiansen was to present his findings at a conference in Madrid on Tuesday organised by the European Society of Human Reproduction and Embryology (ESHRE).
"Among my patients, I have at least 50 who never have a second child after the first birth of a boy, whereas approximately 20 patients did not experience another birth after having a girl," ESHRE quoted him as saying in a press release.
"So there are patients who will never get a second child in both groups, but the risk is larger among women whose first child was a boy."
Christiansen's theory is that a boy unleashes a hostile response from the mother's immune system.
The placenta is created from the foetus and, if it is a boy, carries a male tissue-type that may cause the immune system to perceive it as alien and invasive, and unleash antibodies and white blood cells, he suggests.
The first pregnancy, he believes, proceeds to full term because the pregnancy is safely established by the time the mothers immune system starts to react to the male foetus.
But her immune system may remain switched on after delivery, which means that subsequent foetuses get expelled, Christiansen suggests.
The immune system, along with the central nervous system, is the only tissue in the body that are believed to have "memory," he says. Further studies are planned to see whether the theory pans out.
If it turns out to be true, the next step would be to find a form of "immunisation" against male-specific antigens — the substances that trigger the defence response.
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