Month: April 2014

bookmark_borderWhy can’t my registry be magically generated?

Posted on by ErikaRS

Here’s a product idea for anyone looking for one.

There are lots of baby registry guides out there, but I want one that’s a bit smarter. That knows more about me. Baby products are one of those areas where there’s a lot of choice and where some decisions matter much more than others — and a new parent doesn’t know which is which.

I don’t want a registry guide. I want a registry generator. It would take into account baby’s gender (or unstated), how elaborate of a setup you want (bare bones or all the bells and whistles?), general spending criteria (are you trying to spend as little as you can? is money no object? somewhere between?), and some aesthetic guidelines.

Given this, it would generate a base registry with suggested items and quantities, with no more than 3 options per item. You could then use the same criteria to customize specific items — I might generally be cheap, but want a really high quality stroller. The base registry could then be tweaked like a normal registry: items could be added, removed, replaced, quantity updated.

So who’s going to be the wonderful person to tell me this already exists? =)

bookmark_borderProbability is hard

Posted on by ErikaRS

Our 20 week ultrasound revealed a healthy, growing baby, but there was one worrisome characteristic. Baby had a skin fold on the back of its neck whose thickness was enough to indicate a correlation with an increased chance of Down’s syndrome.

Jeff and I considered not getting any screening — even with this indicator, the chances of Down’s syndrome are pretty low — but in the end, we decided to do a maternal blood screen. Unlike an amniocentesis, this test does not provide a certain answer, but it also doesn’t post the very small but non-zero risk to baby that the amnio does. A blood screen is also more comfortable for me. 
But it does have its drawbacks. The screening has a 99% detection rate and a 0.1% false positive rate[1]. That sounds pretty good, but running the numbers, you’ll see why probability is non-intuitive. 
Given my age and the skin fold measurement, the baseline probability for Down’s is between 1:100 and 1:150. So out of 10,000 babies in this group[2]:
  • 100 will have Down’s syndrome. Of this 100, 99 will be detected by the screen. 1 will be missed.
  • 9900 will not have Down’s syndrome. Of this, 9.9 will be incorrectly be above the risk threshold for Down’s syndrome in the screen. The other 9890.1 will be correctly diagnosed as not having Down’s.
Combining these, if the screen comes back as a “no” there is only a 1:9891.1 chance that baby has Down’s. But a “yes” on the screen indicates a ~90% chance of Down’s and an ~10% chance of not. In other words, a “no” leaves you pretty confident, but a “yes” still has a lot of ambiguity. 
All-in-all, the screen seemed like a better option for us, but these decisions aren’t easy. 
By the way, the results came back negative. Yay!
[1] As claimed by the test provider, but these sorts of measurements are themselves rather difficult to do well.
[2] By the way, this may be completely wrong. Probability was not my strong suit in mathematics. Math with numbers is hard.

bookmark_borderIt’s a… secret!

Posted on by ErikaRS

You may have noticed that the last post didn’t mention baby’s gender. We did choose to find out the gender (verified two ways, in fact), but we’re not telling anyone.

Why? Stereotypes. From pink vs blue to trains vs princesses to selective praise of strength or kindness, even in tiny infants, we start stereotyping children before they are born. Nature vs nurture hardly gets a fair evaluation when almost everything an infant does is perceived through a gendered lens. We can’t stop that, but we can delay it a tiny bit.

Plus, aren’t surprises more exciting? =)

bookmark_borderUltrasound

Posted on by ErikaRS
Baby at 14 weeks (too early to tell gender)

Look! It’s out baby! It looks just like… a generic ultrasound picture.

But still, it’s our generic ultrasound picture, and it’s kind of funny how much of a difference that makes. When you know that the video feed you’re seeing corresponds to a little baby’s movement inside of you, it become more than just another grainy black and white image. It becomes the excitement that baby really does have arms and legs and a heart and brain and everything, just like a real baby!

So, hello baby! You look exactly like I imaged you’d look.