Mom's immune system and boy babies

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Miscarriages greater after boy babies

Main Category: Pregnancy News

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Article Date: 02 Jul 2003 - 0:00am (PDT)

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Women whose first child is a boy are more likely to suffer multiple

miscarriages as they try for their next child, say doctors.

However, a simple injection could overcome the problem - an immune

reaction to proteins unique to male foetuses and their placentas.

Thousands of women in the UK have repeated, unexplained miscarriages,

and many scientists believe that an overreaction by the immune system

could be to blame for many of them.

A scientist from Copenhagen in Denmark studied more than 200 women who

had suffered at least three miscarriages following the birth of their

first child.

Significantly more of these first children were male than female -

immediately highlighting a possible link between gender and miscarriage

risk.

In fact, women who had given birth to a boy were more than a third less

likely to have managed another successful pregnancy than those who had

given birth to a girl.

Dr Ole Christiansen, who led the study, said: 'Giving birth to a son is

known already to be a prognostically negative factor in many obstetrical

complications.

'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.

'These women may have raised an immunological reaction against tissue

types that are expressed on the surface of the placenta in pregnancies

with boys.

Immune attack

'The placenta is created from the foetus and if is a boy it will carry

these male-specific tissue types.

'The mother's immune system may be reacting by forming antibodies, but

also the mother's white blood cells may be reacting against the placenta.'

Treatment hope

However, there is already a possible solution to this - studies have

shown that infusing women who have had recurrent miscarriages with a

drug called immunoglobulin raises the live birth rate.

However, the studies show that it does not improve her prospects if she

has never had a child - suggesting that the birth of the first child is

a key factor in an unwanted immune response.

Dr Christiansen said: 'I believe that we already have a quite efficient

treatment, as our trials have shown.'

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Stress induces miscarriages of males

Submitted by Kambiz Kamrani

<http://anthropology.net/user/kambiz_kamrani> on February 2, 2006 - 6:57pm.

A new study lead by Ralph Catalano

<http://sph.berkeley.edu/faculty/catalano.htm> and Tim Bruckner of the

UC Berkeley School of Public Health <http://sph.berkeley.edu/> has been

published in last week's issue of PNAS, " Secondary sex ratios and male

lifespan: Damaged or culled cohorts

<http://www.pnas.org/cgi/content/abstract/103/5/1639> " that has

interesting implications on human evolution, reproduction, sex & gender,

populations as well as taboo topics like infanticide. Here is the abstract:

" Population stressors reportedly reduce the human secondary sex

ratio (i.e., the odds of a newborn's being male) by, among other

mechanisms, inducing the spontaneous abortion of males who would

have been born live had mothers not been stressed. Controversy

remains as to whether these abortions result from reduced maternal

tolerance of males at the low end of a relatively constant

distribution of survivability (i.e., the " culled cohort "

explanation) or from shifts in the whole distribution of

survivability such that more males fall below a relatively constant

criterion of maternal tolerance for low survivability (i.e., the

" damaged cohort " explanation). These alternatives make opposing

predictions regarding the relationship between the secondary sex

ratio and lifespan of male birth cohorts. We test the hypothesis

that the secondary sex ratio among Swedish cohorts born in the years

1751 through 1912 predicts male cohort life expectancy at birth

(i.e., realized lifespan). Our results support the culled cohort

argument. We argue that these findings have implications for the

basic literature concerned with temporal variation in the secondary

sex ratio, for more applied work concerned with the fetal origins of

adult health, and for pubic health surveillance. "

Previous studies have linked the decline in male births to political

unrest, natural disasters, environmental changes, and economic

recessions. Bruckner and Catalano's data support the idea that stressed

mothers' bodies may develop a mechanism to reject especially weak male

offspring whom they might have otherwise carried to term. In general,

male fetuses are slightly weaker than females and a bit less likely to

survive to birth and changes in a woman's body chemistry when she is

subject to stress can affect males in the womb more than females.

A coinciding theory argues that outside stresses cause a mother's body

to develop a lower tolerance for especially weak males and Catalano and

Bruckner believe they have evidence for this second theory based on

studies of the life spans of babies born during times of societal

upheaval. The results support the behaviorial ecological notion that the

bodies of mothers under pressure reject weaker babies in favor of ones

that can survive in a harsh environment. Furthermore, in times of

stress, it would be more beneficial for females to survive because of

the limited eggs they have throughout their life times.

Though, Catalano and Bruckner's research does not contribute to the

broader goal of understanding why babies are born male or female, their

research contributes to understanding the effects of stress on the

survival of offspring.

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