Dear debmking,
Thanks for your question... Your subject line poses a second question,
and I will address both.
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Timing
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First, with regard to the preferred time to undertake selective
reduction of triplets, the typical time is between 6 and 13 weeks
gestation. "Very early" is considered 6-8 weeks. The procedure is
most commonly performed between 10-12 weeks gestation.
You can read a little more about the procedure at the Eastern Virginia
Medical School Dept. of Ob/Gyn:
://www.google.com/url?sa=U&start=5&q=http://www.mfm-evms.org/acrobat/fetalreduction.pdf&e=9707
_____________________________________
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Risks
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One risk of high concern with most expectant parents in this situation
is loss of the pregnancy. Various studies have been done on this
topic. Reduction of triplets to twins results in a fetal loss risk of
6-8%. For more information, see this article:
The First World Congress On: Controversies in Obstetrics, Gynecology & Infertility
Prague, Czech Republic - 1999
Multifetal Pregnancy Reduction ? First or Second Trimester. S.
Lipitz. Department of Obstetrics gr Gynecology, Chaim Sbeba Medical
Center, Tel Hashomer, Israel
http://www.obgyn.net/displayarticle.asp?page=/firstcontroversies/prague1999lipitz
Word format:
http://www.obgyn.net/firstcontroversies/prague1999lipitz.doc
References [10, 13, 16, and 19] in the above article discuss this further.
_____________________________________
The 6-8% figure varies in different studies. The study below,
performed in Greece, looked at reduction of pregnancies to twins.
Antsaklis AJ, Drakakis P, Vlazakis GP, Michalas S. Reduction of
multifetal pregnancies to twins does not increase obstetric or
perinatal risks. Hum Reprod. 1999 May;14(5):1338-40.
The abstract can be found here:
http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=pubmed&dopt=Abstract&list_uids=10325290&query_hl=4
The free full text version of the article can be read here:
http://humrep.oupjournals.org/cgi/content/full/14/5/1338
As stated in the Discussion portion of this paper, "Both groups of
patients [pregnancy with twins initially vs. those reduced to twins]
had the same obstetric outcome according to perinatal mortality,
gestational week at delivery, weight of neonates at birth and
miscarriage rate. Many years of practice has made the technique of
multifetal pregnancy reduction a very safe procedure."
_____________________________________
WebMD has a page, along with a few references, on multifetal pregnancy
reduction (MFPR, alternately MPFR):
http://my.webmd.com/hw/health_guide_atoz/aa75652.asp#aa99940
According to this source, the risks of MFPR procedures include:
* Miscarriage of the remaining fetuses. From 4% to 8% of medically
reduced pregnancies miscarry. The greater the number of fetuses
originally present, the higher the risk of miscarriage.
* Premature birth.
* Infection of the abdomen or uterus (rare)
Of course, these risks must be compared to the occurrence of the same
events in pregnancies (e.g. twins) that occur without reduction.
Also, one must weigh the considerable risks to both mother and fetuses
incurred by attempting to carry a multiparous pregnancy to term.
_____________________________________
One of the best articles on the topic I have come across is freely
available from the World Health Organization:
http://scholar.google.com/url?sa=U&q=http://www.who.int/reprodductive-health/infertility/22.pdf
This 15 page article discusses the multiple potential complications
that can occur with multiple fetus pregnancies, giving references for
each. An excerpt, relevant to MFPR risks summarizes the available
data:
"However, multifetal pregnancy reduction comesat a cost. Postprocedure
pregnancy loss rates are reported as 8%?23%, depending on the starting
number of fetuses, while the delivery of severely premature fetuses
vary from 9% to 23% (75). The importance of increasing technical
experience on lower rates of pregnancy loss has been emphasized by
many authors (76?79). Analysis of 3513 MFPR procedures at 11 centres
in five countries highlighted this trend of improved outcomes in
pregnancy losses and early prematurity with time and experience. They
reported a collaborative loss rate of 4.5% for triplets, 7.3% for
quadruplets, and 15.4% for sextuplets or higher-order multiple
pregnancies (80). Selective reduction for fetal abnormality, which is
similar in technique to MFPR, was reported in all trimesters with good
outcomes for the surviving fetus in >90% of cases (81). Geva et al. as
well as others published high success rates with second-trimester MFPR
(82?85), although the first-trimester approach still remained safer
(5%?6% miscarriage rate in first-trimester versus 8%?16% in
second-trimester MFPR). Differences in pregnancy loss following
reduction at different gestational ages were attributed to varying
background risks of spontaneous miscarriage (86). Based on these
favourable reports on second-trimester fetal reduction and the
anticipation of high spontaneous resorption rates during the first
trimester, it was recommended that MFPR should bedelayed until 12
weeks? gestation in quadruplet or higher multiple gestations. However,
this was not felt to be necessary in twin and triplet gestations
(87)."
I highly recommend reading the full text for more details and
discussion of other aspects of this issue.
Some other potentially useful articles are listed below.
_____________________________________
The Cochrane Evidence Based Medicine Database article on MFPR states
that now controlled randomized trials have been carried out to compare
risks and outcome with non-reduced and reduced pregnancies.
_____________________________________
A study of 148 women with triplet pregnancies was performed in France
by Boulot, et al.
Pierre Boulot, Jacques Vignal, Christine Vergnes, Hervé Dechaud,
Jean-Michel Faure and Bernard Hedon, Multifetal reduction of triplets
to twins: a prospective comparison of pregnancy outcome, Human
Reproduction, Vol. 15, No. 7, 1619-1623, July 2000.
The full text can be found here:
http://humrep.oupjournals.org/cgi/content/full/15/7/1619
_____________________________________
Brambati, Bruno. Tului, Lucia. Camurri, Lamberto. Guercilena, Stefano.
First-trimester fetal reduction to a singleton infant or twins:
outcome in relation to the final number and karyotyping before
reduction by transabdominal chorionic villus sampling. American
Journal of Obstetrics & Gynecology. 191(6):2035-40, 2004 Dec.
Author e-mail: first.cvs@fastwebnet.it
The abstract for this article can be read here:
http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=pubmed&dopt=Abstract&list_uids=15592288&query_hl=1
The Discussion portion of the above reference sums up the findings of
this with regard to pregnancy risks:
"The safety of MPR is further emphasized by the lack of statistical
differences between reduced pregnancies and control series in relation
to perinatal deaths, very premature births (<33 weeks of gestation),
and lightest newborn infants (<1500 g). A significant increase was
seen in both study series only for mild prematurity (between 33 and 37
weeks of gestation) and low birth weight (between 1500 and 2500 g); a
higher pregnancy loss rate and lower mean birth weight were limited to
the series of reduced to a single fetus. Our findings are not
surprising, because 92% of pregnancies in the study population
resulted from assisted reproductive techniques, and in these
pregnancies, a higher miscarriage rate is expected. Furthermore,
singleton infants after in vitro fertilization are born on average 1
week earlier and weigh 400 g less than the control infants,4 and
higher rates of preterm deliveries and very low birth weight babies
have been described in intracytoplasmic sperm injection pregnancies.
However, the chronic inflammatory process that arises from the
resorption of necrotic tissue could be an additional factor that leads
to a less favorable outcome after MPR. Because pregnancy loss occurred
in both study series several weeks after reduction (median, 8 and 9
weeks), establishing a definite causal relationship with fetal
reduction becomes very difficult. Reduction to a single fetus is seen
to have a favorable impact on the pregnancy outcome. In comparison to
the series of reduced to twins, the rates of premature delivery, low
birth weight, neonatal death, and pregnancy complications were
significantly lower, although abortion rates were not statistically
different between study series.
When possible, in MPR, it is ethically and morally desirable ensure
that fetuses with severe abnormalities are identified for reduction.
Ultrasound signs are very efficient in this respect; however, because
their sensitivity for chromosomal abnormalities is not 100%, fetal
karyotyping should be considered."
To summarize this, the group found that reducing a multiparous
pregnancy, whether due to to a singleton (one fetus) results in a
significant improvement compared to reduction to twins with regard to
prematurity, low birth weights, pregnancy complications.
Essentially, starting off with triplets or a greater number of fetuses
results in greater risks, as outlined above. Reduction to twins or
singleton reduces these risks to the same level as if the fetuses were
conceived start as twins or singletons.
_____________________________________
A group in Israel (Coffler, et al.) published a paper comparing
maternal complications with MFPR performed with potassium chloride
(KCl) injection versus transvaginal selective embryo aspiration,
showing lower complication rates for the latter.
Mickey S. Coffler, Shahar Kol, Arie Drugan, and Joseph
Itskovitz-Eldor. Early transvaginal embryo aspiration: a safer method
for selective reduction in high order multiple gestations. Human
Reproduction, Vol. 14, No. 7, 1875-1878, July 1999.
Full text:
http://humrep.oupjournals.org/cgi/content/full/14/7/1875
_____________________________________
I hope this information was useful. With regard to one commenter's
statement that such procedures should more properly be termed
"abortion," I was unable to locate an appropriate term for the loss of
one or more fetuses that occurs when one attempts to carry a grand
parous pregnancy to term and one or more of the fetuses is lost -
tragic, heart-breaking, perhaps. Each person making such a weighty
decision must weigh the significant risks of attempting to carry a
multiparous pregnancy to term without reduction vs. the obvious
ethical dilemmas involved.
Please feel free to ask for any clarification.
Best,
-welte-ga |
