Women with DZ twins can be counselled that the chance of their pregnancy producing a child with Down's syndrome is theoretically double their age-related risk, whereas women with MZ twins simply have their age-related risk that both twins will be aneuploid. Nevertheless, there is some evidence that Down's syndrome may occur less frequently in twins [17,18]. Serum screening is inapplicable in multiple pregnancy, because aberrant placental or fetal hepatic hormone production in an affected twin is masked by normal levels from the unaffected co-twin. In contrast, nuchal translucency, although rarely used in isolation any more in singletons because of its high false positive rate, is readily applicable as a fetally-specific marker. Because the background rate of increased neckfolds is doubled in MC twins, the average of the twins' measurements is used to avoid high false positive rates .
Was this article helpful?
The first trimester is very important for the mother and the baby. For most women it is common to find out about their pregnancy after they have missed their menstrual cycle. Since, not all women note their menstrual cycle and dates of intercourse, it may cause slight confusion about the exact date of conception. That is why most women find out that they are pregnant only after one month of pregnancy.