Hope the rest of your pregnancy goes smoothly. If it counts for anything, my mom had me at 35 and I'm perfectly fine at 21 years old, a little slow sometimes but that could be the pregnancy brain. Chorionicity determination in twin pregnancies, how accurate are we? http://www.countdownmypregnancy.com/tickers/countdown-1350882000z1375074000zb.png. The association of crown–rump length discrepancy with birthweight discordance in spontaneous versus assisted conception dichorionic twins. In MZ twins, both fetuses are assumed to be affected and the probability (Px, MZ) is Px. Start by selecting which of these best describes you! The scans were carried out by four sonographers, two of whom were medically qualified; all were certified by the Fetal Medicine Foundation. The most likely explanation is that these two cases were in fact DC as the authors do not discuss this unexpected finding or state how they established zygocity. The correlation coefficients in affected twin pregnancies are calculated by dividing the covariance in the unaffected pregnancies by the appropriate standard deviations. Second‐trimester severe twin–twin transfusion syndrome is not uncommon in MC twins and a large disparity in NT thickness between the fetuses is regarded as an early marker for the syndrome (Sebire et al., 1997). Standardising for the maternal age distribution in the Caucasian women, the DZ twinning incidence was 54% higher in the Afro‐Americans. If you do not receive an email within 10 minutes, your email address may not be registered, Those are FANTASTIC odds for a perfect and healthy baby. I am 38 so at a higher risk and I was 35 with my last pregnancy (also high risk) One of the things we tried to remind ourselves of whenever we heard "chances and risks" is that they are simply that. I know it's easier said then done. Before taking the scan, the maternal age‐specific odds of Down syndrome are 1:1357 for fetus 1 alone, 1:1357 for fetus 2 alone, 1:273 618 for both fetuses in DZ and 1:1351 in MZ twins. National Down Syndrome Cytogenetic Register and the Association of Clinical Cytogeneticists, Health and demographic characteristics of twin births: United States 1988, First trimester screening with free beta‐hCG, PAPP‐A and nuchal translucency in pregnancies conceived with assisted reproduction, Nuchal translucency thickness and crown‐rump length in twin pregnancies with chromosomally abnormal fetuses, The changing epidemiology of multiple births in the United States, Increased nuchal translucency thickness at 10–14 weeks of gestation as a predictor of severe twin‐to‐twin transfusion syndrome, Screening for trisomy 21 in twin pregnancies by maternal age and fetal nuchal translucency thickness at 10–14 weeks of gestation. Correlation coefficients between the log MoMs were calculated after excluding outliers exceeding the median by at least 3 standard deviations, based on the 90th and 10th centile difference divided by 2.563. Even when maternal serum markers are measured concurrently, the performance is comparable with singletons. If you were 1 of 340 people in a room and someone told the group one person there was going to win a million dollars - you would be excited for the chance, but you wouldn't quit your job on the spot assuming it would be you with 339 other people eligible too, right? We have also described in detail a method to calculate Down syndrome risk in a twin fetus using its own NT and that of the co‐twin. In a study from the National Down Syndrome Cytogenetic Register of England and Wales for the period 1989 to 1993, among 72 affected twins registered, 9 (12.5%) were concordant for Down syndrome, all of which had the same gender (Mutton et al., 1996). I am really grateful for the option of knowing ahead of time if this baby does have Down syndrome, so that we can prepare for that IF that is the case - while it is not a life I would CHOOSE for my child, it is a known syndrome with a lot of resources and support available. The examples showed very large differences in the risks obtained when the extent of correlation in NT between fetuses is taken into account and when the measurements are treated as independent. Definitely agree, those odds (0.29%) sound good to me. The #1 app for tracking pregnancy and baby growth. Model predicted Down syndrome detection rates for nuchal translucency screening in twin pregnancies. In the largest published study, in France, the NT and CRL values of 14 affected twins, all but one discordant, were tabulated (Garchet‐Beaudron et al., 2008). (2006) in a series of 181 unaffected twins from Denmark reported a correlation coefficient of 0.34 between the pairs of NTs, expressed in log multiples of the median (MoMs) for CRL. At mid‐trimester, the recurrence factor is 0.54% instead of 0.42% (Cuckle and Benn, 2010). Aug 15 April Siggy challenge: Baby Shower fails: Sometimes the unexpected news is difficult to process. Even with 1/35 odds, that's a 97% chance this baby is "normal" (based on chromosomes at least). But like a previous post. All DC pregnancies where the fetuses have different genders can be taken to be DZ: WDZ 100% and WMZ 0%. Enter your email address below and we will send you your username, If the address matches an existing account you will receive an email with instructions to retrieve your username, These are calculated for the following: fetus 1 affected and fetus 2 unaffected (LR, By continuing to browse this site, you agree to its use of cookies as described in our, BJOG: An International Journal of Obstetrics & Gynaecology, International Journal of Gynecology & Obstetrics, Acta Obstetricia et Gynecologica Scandinavica, Australian and New Zealand Journal of Obstetrics and Gynaecology, Journal of Obstetrics and Gynaecology Research, I have read and accept the Wiley Online Library Terms and Conditions of Use, Nuchal translucency thickness in monochorionic multiple pregnancies: value in predicting pregnancy outcome, Difference in nuchal translucency between monozygotic and dizygotic spontaneously conceived twins, Multianalyte maternal serum screening for chromosomal defects, Genetic Disorders and the Fetus: Diagnosis, Prevention and Treatment, Estimating a woman's risk of having a pregnancy associated with Down's syndrome using her age and serum alpha‐fetoprotein level, Congenital malformations in twins in England and Wales, Maternal and environmental factors affecting twin births in Canadian cities, Second‐trimester Down syndrome maternal serum marker screening: a prospective study of 11 040 twin pregnancies, The Registrar General's Statistical Review of England and Wales for the year 1960. Copyright © 2010 John Wiley & Sons, Ltd. Maternal serum screening for Down syndrome has much lower performance characteristics in twin pregnancies compared with singletons. Fetus‐specific Down syndrome risks in twins should be calculated using its own NT value as well as that of the co‐twin. There have been suggestions that the NT thickness is higher in MC twins than DC, possibly due to twin–twin transfusion (Sebire et al., 1996; Monni et al., 2000). Thanks everyone for ur feedback! LRs express the relative probability of being affected compared to unaffected, for a given marker profile, hence the need to express prior probabilities as odds at that stage in the calculation. There are no reliable data to directly estimate the age‐specific probability of having twins concordant for Down syndrome and we have used an indirect approach. The Down syndrome means at 11, 12 and 13 weeks of gestation were those derived by meta‐analysis, 2.30, 2.10 and 1.92 MoM or 0.362, 0.322 and 0.283 log10 MoM, respectively (Cuckle and Benn, 2010). Thank u! We have confirmed that there is a correlation between the NT values in twin fetuses and obtained an unbiased estimate of the correlation coefficient.