Questions about Rhesus factor

hierophant wrote:

I just wrote...


The injection is usually timed to be within 72 hours (which is an arbitrary
number), but it can be immediately following birth or up to one year.


erp... I meant one month, not year. Rh(D)- mothers to Rh(D)+ babies
should be given RhoGAM within 72 hours for best results, but up to 28
days following birth before mother mounts an immune response to Rh(D)+
fetal cells. (Source for that is Understanding Diagnostic Tests in
the Childbearing Year, Anne Frye; a clearing house for summaries and
guidelines to labs for midwives)

Whew! That sounds better. Yes, it's still useful to
28 days, but given what a huge impact getting sensitized can
have on future pregnancies, I'd work hard to make the 72 hour
window of maximum effectiveness. (It's small numbers, but
large consequences if you're planning more pregnancies.)

Best wishes,
Ericka

"Ericka Kammerer" wrote in message
...
hierophant wrote:

The injection is usually timed to be within 72 hours (which is an
arbitrary number), but it can be immediately following birth or up to
one year.

Huh? If you miss the 72 hour window, your odds of
getting sensitized increase dramatically!


Based on what evidence? I read Sara Wickam's book and IIRC there were no
studies on this whatsoever. IIRC the 72 hour window had to do with
guidelines on testing prison inmates. The only applicable evidence was
other studies of other issues and how long it takes the spleen to kick into
gear.

Dagny wrote:

"Ericka Kammerer" wrote in message
...

hierophant wrote:

The injection is usually timed to be within 72 hours (which is an
arbitrary number), but it can be immediately following birth or up to
one year.

Huh? If you miss the 72 hour window, your odds of
getting sensitized increase dramatically!

Based on what evidence? I read Sara Wickam's book and IIRC there were no
studies on this whatsoever. IIRC the 72 hour window had to do with
guidelines on testing prison inmates. The only applicable evidence was
other studies of other issues and how long it takes the spleen to kick into
gear.

Sorry, I was a little extra worked up there, thinking
about waiting a *year* to get a RhoGam shot ;-) I wouldn't
say the odds go up dramatically, just that they go up. IIRC,
there was a woman on m.k or m.k.p some time ago who got it
late and was sensitized. I think it was about a week before
she got it. There's no guarantee it was the late postnatal
shot, of course, but some people's immune systems move fast.

Best wishes,
Ericka

Ericka Kammerer wrote in message ...

Not quite. Dad could be phenotypically Rh(D)+ and
genotypically +-.

Right, Ericka and Amy. Obviously it was easier to post in
generalities, than it is to write a novel on blood systems!

Sorry about the typo-- didn't mean to work you up over the year wait
to get a RhoGAM shot It was one of those things I couldn't unsend!
:P

Kris

hierophant wrote:

Sorry about the typo-- didn't mean to work you up over the year wait
to get a RhoGAM shot It was one of those things I couldn't unsend!
:P

Been there, done that ;-)

Take care,
Ericka

On Sun, 28 Mar 2004 08:37:04 +1200, "Cathy"
wrote:
but then again I might just have mucked up the snipping as usual!
Hi everyone, My nearly-15 month old has decided to wean herself, so I am
hoping that this will mean the return of my fertility, so that we can really
TTC in earnest. But in the meantime I want to get some answers to my
quesions. I am Rh -, my husband and daughter are Rh +. After DD's birth, I
had the Rhogam shot (or the equivalent) about 2 days after the birth. I was
surprised at this - I thought it would be almost immediate.

Thats fine - Anti-D (RhoGam being a brand name) has to be given with
72 hours of the birth, so you're covered. Did they do a Kleihauer
test? Assuming they did and adjusted the Anti-D dose accordingly (and
you had no bleeds, bangs to the bump etc during pregnancy with your
daughter), your chances of having problems are virtually nil. Where
people are sensitised despite having anti-D its usually because they
either weren't given enough (no Kleihauer test performed and a
'standard' dose given, but feto-maternal haemorrhage was too high for
the standard dose to cover) or because they had a sensitising event
during pregnancy and did not receive anti-D.

Even without anti-D the risk of sensitisation with normal pregnancy,
labour and delivery and physiological third stage is quite low, though
of course the risks if you *are* sensitised are quite high: (20%
mortality rate, 20% severe morbidity, 20% mild to moderate morbidity,
only 40% unaffected).

You'll probably be tested for anti-bodies when pregnant and in the
unlikely event of you being sensitised there is a lot that can be done
now to lower the risks to the baby.

Megan
--
Seoras David Montgomery, 7 May 2003, 17 hours: sunrise to sunset (homebirth)

To e-mail use: megan at farr-montgomery dot com

On 27 Mar 2004 19:39:44 -0800, (hierophant) wrote:
but then again I might just have mucked up the snipping as usual!
The injection is usually timed to be within 72 hours (which is an
arbitrary number), but it can be immediately following birth or up to
one year. (FYI: The Rh(D)- factor is recessive, so when paternity is
certain and his blood type is Rh(D)+, mother will be making Rh(D)+
babies.)

Only if he is carries two Rh+ genes. If he has a Rh+ and a Rh- there
is a 50% chance of a child being Rh- as well. Likewise the reverse is
true: My parents were OO+- and AB+-, I am AO- - and my brother is BO,
IIRC, all four of us having different blood types!). My husband is
AO+?, we don't know his second Rh gene yet, since Seoras was OO+-.

Megan
--
Seoras David Montgomery, 7 May 2003, 17 hours: sunrise to sunset (homebirth)

To e-mail use: megan at farr-montgomery dot com

On Sun, 28 Mar 2004 17:58:00 +1200, "Amy"
wrote:
but then again I might just have mucked up the snipping as usual!

An Rh- mother and Rh+ father can still produce Rh- children, my parents and
I are proof of this. True it is more likely that the baby will be Rh+

As you go on to say yourself - chances are exactly even.

In my parents' situation, both being Rh+ but both carrying a Rh- gene,
they had only a 25% chance of producing a Rh- child, (i.e. me).

Megan
--
Seoras David Montgomery, 7 May 2003, 17 hours: sunrise to sunset (homebirth)

To e-mail use: megan at farr-montgomery dot com

On 28 Mar 2004 19:01:37 -0800, (hierophant) wrote:
but then again I might just have mucked up the snipping as usual!
Ericka Kammerer wrote in message ...

Not quite. Dad could be phenotypically Rh(D)+ and
genotypically +-.

Right, Ericka and Amy. Obviously it was easier to post in
generalities, than it is to write a novel on blood systems!

Sure, but its important to make this clear to future clients: they
can then make the choice to wait until baby is typed before having
anti-D, in case its not necessary! Likewise of course, they should
also request a kleihauer test (though I understand these are not
available in the US and I assume not other places either - had to
explain what one was to an OB/GYN over there the other week).

Megan
--
Seoras David Montgomery, 7 May 2003, 17 hours: sunrise to sunset (homebirth)

To e-mail use: megan at farr-montgomery dot com

Buzzy Bee wrote:

On Sun, 28 Mar 2004 17:58:00 +1200, "Amy"
wrote:
but then again I might just have mucked up the snipping as usual!


An Rh- mother and Rh+ father can still produce Rh- children, my parents and
I are proof of this. True it is more likely that the baby will be Rh+

As you go on to say yourself - chances are exactly even.

Only if you know that the Rh+ parent's genotype is +-.
If the Rh+ parent's genotype is ++, then there's no possibility
of the child being Rh-. So, if the genotype is *unknown*, the
probability is greater than 50/50 that the child will be Rh+
(make sense? ;-)

Best wishes,
Ericka