Monthly Archives: November 2011

Pregnancy Update – Week 12

Posted on by
4

This week we had another ultrasound. This time it was for genetic testing. We were screening for Trisomy 18, Trisomy 13 and Down Syndrome.

Trisomy 18 is called Edwards Syndrome and happens when there are 3 as opposed to 2 copies of chromosome 18. The syndrome has a very low rate of survival, resulting from heart abnormalities, kidney malformations, and other internal organ disorders.

Trisomy 13, also called Patau Syndrome. It is an extra or third copy of chromosome 13.  An extra chromosome here will interrupt the normal course of development, causing heart and kidney defects.

Before we took the tests, which include a blood draw and ultrasound, we had a statistical risk of 1 in 190 for both Trisomy 18 and 13. After the test we were reduced to 1 in 3,781. Both babies were considered within a safe range, no further screening is required or recommended.

Down Syndrome is an extra chromosome on chromosome 21. This impairs cognitive ability and physical growth. For this test they use the Nuchal Translucency Scan, measuring the fluid behind the babies necks. We were told that under 3mm is good.

Both ultrasound technicians were very positive about our twins Nuchal Translucency, which was under 2mm on our ultrasound this week and last week. Twin A was measuring 1.7 mm. Twin B was 1.8 mm.

I walked into the doctor’s visit after the screening very confident. So you can imagine our surprise (Adam was with me, and Jack & Ben) to find that Twin B was showing ‘increased risk’ for Down’s. I little millimeters difference between Twin A and Twin B put one in a safe range and one in an increased risk range!

Before we had the tests, both twins had a 1 in 106 chance of having Down’s Syndrome. After the test Twin A had a 1 in 309 chance and Twin B had a 1 in 252 chance. So taking the test dropped our odds of both kids having Down’s Syndrome, just not enough for the doctor to feel comfortable.

If we want to do more testing there are a few options.

We could have a Chorionic Villus Sample (CVS) done. It is similar to an Amniocentesis, but instead of drawing fluid from the amnio sac, they take a sample of the placenta. At this point, the chance of miscarriage from the CVS test are about the same as having a baby with Down’s Syndrome.

Or we can wait another month and have the United Screening Approach. It is simply a blood draw that combines your first and second trimester screenings. It detects at least 97% of cases of Down syndrome with an overall false positive rate of 5%.

We had planned to do the United Screening Approach even before the tests came back, as we have with all our other pregnancies. We decided to wait on the results of these tests before we decide anything further. The blood draw for this test can be performed anywhere from 15 – 22 weeks into the pregnancy. I’ll let you know how it turns out…

Pin It

Twin Trivia

Posted on by
Reply

Seems like every time we talk to someone about the fact that we are carrying twins, we discover a new and exciting fact about twins. It occurred to me that I must still be in shock, otherwise I would be out there reading and researching our current situation instead of walking around in an ignorant haze.

So I did some research.

Here is what I found.

1. Are we having identical or fraternal twins?

The likelihood of identical twins is uniformly distributed in all populations around the world. The exact cause for the splitting of an embryo is unknown. It is spontaneous and not effected by family history or fertility drugs. They occur in 1 out of 250 births on average worldwide. Our twins have two separate sacs and two separate placentas but this does not rule them out as identical. 

Most twins are fraternal.  Fraternal twins develop from two separate eggs. Fraternal twins are conceived when two eggs are released during ovulation. Because of fertility drugs, the birth rate for twins has gone up 65 percent since 1980. Before it was one in 89. These days, about one in 32 births are twin births.

2. Are there any factors that may have increased my chances of having twins?

If fraternal twins run in a female’s family, her odds of conceiving twins are much greater. It is passed down from mother to mother. Or if the mother carries the twin gene and has a son, he may pass it down to one of his daughters who will then be more likely to have twins. My mother is not a twin. Nor is my husband’s mother.

Decreasing our chances even more is my Asian ethnicity. China has the lowest rate of twins with the chance for multiple births averaging only one in 300.

Another factor that increase twins that doesn’t fit us – we did not previously have a multiple pregnancy. 

Also, we did not take any fertility drugs. Fertility drugs increase your chance of having multiples from one in 89 to one in 4.

With each pregnancy you are more likely to conceive twins. Perhaps having two other children previously is a factor for us.

More twins are conceived in July, and the least in January. We conceived July.

More multiple births occur if the mother is obese. I was not obese when I conceived. Maybe soon I will be, though.

Older mother’s have an increased chance of conceiving twins. I’m 38 years old. That’s old.

3. I also read that twin have a 50% chance of delivering before 37 weeks. Maybe I won’t have Taurus babies after all.

4. I am more likely to have a boy/girl combo. Between 30-39 you are more like to have opposite sex. Older women are more likely to produce more than one egg at a time. Between 20-29, same sex is more likely.

5. Finally, I found it interesting that once they are born I am even less likely to understand them than my other kids. Twins have been known to develop their own language that only they understand. 

 


Pin It