This article is from the Pregnancy Screening FAQ, by Lynn Gazis-Sax (firstname.lastname@example.org) with numerous contributions by others.
From Robbrenner@aol.com (Robert Brenner MD)
II 1. Screening tests prior to pregnancy: Measles and Rubella immunity
tests. HIV. STD(can be done early in pregnancy). Tay-Sachs.
[And, in answer to further questions from me]
1)STD stands for sexually transmitted diseases.
2)If your immune to rubella on premarital blood work, it probably is not
necessary to repeat the test. It will be repeated however with each
4)Group B strep is a controversial area. The Group B strep is a bacterium
which can be seen in 15-20% of normal pregnant women. Studies have been done
with routine prenatal cultures and if positive then treatment. The
recurrence rate after treatment is quite high. Also, some women will culture
negative at one time and in fact have the Group B strep bacteria at a later
date. Even if a woman carries the strep it usually does not affect her baby.
The present recommendation of the American College of OB-GYN is not to do
routine cultures as they are inaccurate and not cost effective. Patients
should be cultured and treated if they are in pre-term labor, if they have
ruptured membranes for over 16 hours, if they are febrile while in labor, or
if there is a previous history of delivering a baby infected with the Group B
Strep. Present research is in the area of finding either a vaccine against
the Group B strep or finding a rapid diagnostic test that can be done on all
patients in labor. [Added note from LGS: Further information about Group B
strep can be found at http://www.childbirth.org/articles/comp.html.]
There are a variety of different carrier tests, including, but not limited
to: Tay-Sachs, sickle cell, thalassemia, fragile X, alpha1 antitryptiphine
deficiency, glucose-6-phosphate dehydrogenase deficiency, and less precise
ones for Duchenne muscular dystrophy and hemophilia (Nelson Textbook of
Pediatrics). Sickle cell anemia is chiefly found in people of African
descent. Tay-Sachs is chiefly found among Eastern European Ashkenazi Jews
and French Canadians. Thalassemia is several hemoglobin disorders, found
among people of Mediterranean or Southeast Asian descent. For these,
carrier screening is offered to peple of the appropriate ethnic
background. Other carrier screening tests may be offered if family
history warrants it.
1a. What are some cases where early recipients of a vaccine may lose
immunity, or people who were screened early for carrier status (e.g. for
Tay Sachs) may have invalid results? At what date was an acceptable test
or vaccine formulated?
From Tracy Lee Murphy:
Could you look up three things for me?
Sure, here we go. I can send you copies of the citations if
necessary, but for the sake of brevity I'll keep it short.
1) The early measles vaccine was not as effective as the current one.
People vaccinated before a certain date will have been vaccinated
with the less effective version. I have misplaced my note about what
the year was that the vaccine was improved. Could you find that out?
>Study pub JAMA 1990 264(19):2529-2533
>Measles outbreak causes: vaccinations given before age of 15 months
>and vaccinations before a change in the measles VACCINE STABLIZER
2) Could you check whether there was any similar problem with an
early version of the rubella vaccine? I heard a net rumor to that
effect, but all I have is that an MMR booster has been added to the
schedule which wasn't there originally. It could be that the person
who emailed me had heard from someone who confused the measles and
rubella vaccines, but I want to check.
>I will assume that this was a measles/rubella mixup. The journals
>even seem to treat them as one subject. Everything I'm seeing says
>that a revaccination in high school is necessary even if the child
>got the early childhood set of shots.
3) Same question for Tay Sachs. A carrier screening test came out
in 1971. Was the early carrier test the same as the current version,
or was it less reliable (in which case people whose parents got results
saying they were not carriers might still want to be screened themselves)?
>I found a variety of highly technical articles on Tay Sachs (which
>proteins/antibodies, Jewish/Jewish v. Jewish/Irish testing, etc.)
>I don't want to count on my non-scientific method of scanning journal
>articles on this. The articles I understood said that *most*
>parents (Jewish) don't do testing unless a family member has had a
>Tay Sachs child and that education was still needed (1992 study).
>It does sound like there are a couple of different Tay Sachs tests
>used by ?different labs/doctors/countries?
>I don't feel too good about this info, sorry.
This is for a FAQ on prenatal tests (though the first two would also
be relevant for the Childhood Vaccination FAQ).
>I hope this helps. If you need more, just drop me a line.
tracy lee murphy