A Gizmodo investigation into some of the nation’s biggest data brokers found more than two dozen promoting access to datasets containing digital information on millions of pregnant and potentially pregnant people across the country. At least one of those companies also offered an extensive catalog of people using birth control targeted by more restrictive states, But is this true?

Gizmodo identified 32 brokers across the U.S. selling access to the unique mobile IDs from some 2.9 billion profiles of people pegged as “actively pregnant” or “shopping for maternity products.” Also on the market: data on 478 million customer profiles labeled “interested in pregnancy” or “intending to become pregnant.”

But what is a “unique mobile ID,” and how is it used?

A Mobile Device ID is a unique customer identifier to distinguish a mobile device. More than half the smartphone apps The Wall Street Journal tested sent a serial-number-like identifier for the phone to tracking companies. Some tracking companies use these IDs to create profiles of cellphone users for marketing purposes.

Marketers are always trying to understand consumers better in a digital world where consumers engage daily across various media platforms; keeping track of who’s who and wh t’s’ what can be challenging. Unique mobile IDs allow marketers to serve relevant ads to targeted audiences without revealing personal information like names and addresses. There are benefits to this type of marketing.

1ne: By targeting consumers based on their unique mobile device ID, you know that who you are reaching out to is a real, verified user and not a fraudulent nt ad bot. You can build accurate audience segments by verifying real users and understanding their unique media preferences. Mobile audience segmentation observes mobile consumer behaviors such as app downloads, usage, and purchasing habits.

2wo: Deterministic Matching. A deterministic match is when you build a direct link between a user’s unique mobile device ID and his or her consumer data.

3hree: Driving conversions. With mobile device ID tracking, you’re no longer wasting ads by delivering to a place that gains no engagement because it’s’ the wrong person or it’s’ not even a real person. By optimizing your campaigns to real, verified users who have a high propensity to engage on specific media, you are increasing the accuracy of your marketing initiatives and the likelihood that people will respond to them.

Consumers understand the trade-off between ads and paid media. They want relevant ads, and unique mobile IDs can help serve relevant ads, but it does not reveal who you are, where you live, or you phone number. I believe Gizmodo should have done a better job.