Emily Oster, PhD

2 minute read Emily Oster, PhD
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Emily Oster, PhD

How Can I Measure My CMV Risk?

Q&A on planning to TTC

Emily Oster, PhD

2 minute read

Somewhat of a niche question here, but hopefully, a solid exercise in evaluating risk. My wife and I (same-sex couple) have a 21-month-old and are planning for our second child. Originally, we were set on having me carry the second baby, as my wife carried our daughter, who was born via C-section. However, after reading your post on CMV, we’re concerned about that plan, as I’m CMV-negative. How do we evaluate the risk of being pregnant and CMV-negative with a toddler at home vs. the potential risks with a second IVF pregnancy after C-section? Most couples don’t have the luxury of choosing who becomes pregnant, but I almost wish this decision were made for us.

—Conflicted because of… too much data?

I have talked about the importance of recognizing that no option is risk-free; here, you’re clearly articulating a trade-off between two (very slightly risky) options and being clear on them. So, excellent.

Pavel Danilyuk

To answer: luckily, both sides of this risk coin are low-risk. Pregnancy after a single C-section has a slightly elevated risk of placental complications, but only slightly; these risks increase more substantially after multiple surgeries.

I’ve written about CMV previously, so we can draw some numbers from here. If you haven’t had primary CMV before, the estimated risk of transmission is about 2% per year, so let’s say 2% over the course of the pregnancy. The risk of passing the virus on is then about 40% if you did have a primary infection, so the overall risk is about 0.8%. I will note that if your wife is a carrier of CMV, she would also have a risk of transmitting to the fetus, also around 1%. In either case, there is some small risk here. In your case, you could significantly mitigate this risk by being careful about saliva transmission with your daughter (no mouth kissing, no sharing food).

Bottom line: From a risk standpoint, these are both in line with the kind of risks you take every day without thinking about it. So this decision should likely be made based more on your family preferences.

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