Research paper:
https://arxiv.org/html/2606.26276v1

Jo & Reaves found mobile apps still tracking health data to mobile ad networks. Their paper shows the high specificity which these events are tracked, which trimester, etc

What's crazy is that this was already litigated by FTC and class action law suits, I'm surprised it's still happening

The Research paper:
https://arxiv.org/html/2606.26276v1

My thoughts from my blog on this, just reposting here to save you a click, but full link at bottom.

When Yeeun Jo, a student at University of Illinois at Urbana-Champaign (UIUC) contacted me in 2025 to ask about data tracking in app advertisements related to women’s health and pregnancy I was a bit skeptical. I think I first told her along the lines that while such data collection was broad it was rarely so specific as the advertisers were unlikely to act on specific information like which week of pregnancy a woman was currently in.

Not to mention, Facebook’s historic $5 billion FTC fine for deceptive third-party data tracking, and the FTC’s subsequent 2021 crack-down specifically targeting Flo Health for passing intimate logging metrics to Facebook’s SDK. I thought it was unlikely they’d find much.

10 years of ad experience, and I’m still wrong on what ends up tracked

Well, it’s a year later and Yeeun was 100% correct in her guess that mobile apps and mobile ad networks were still tracking more data than I expected. She and Brad Reaves released their paper “Expecting (Targeted Ads)? Network Analysis of User Health Data Leakage in Fertility Tracking Apps” showing the high specificity which these events are tracked.

I think what was surprising here is the accuracy of the X weeks and X months pre and post birth that were surprising here. While I of course would have expected the categories themselves like pregnancy / ovulation etc to be passed as those would be the easy high value adds for a pregnancy app to increase their monetization, the specificity of the time was much deeper than I expected.

If you didn’t catch them in the lists there are plenty of things that stand out like apps sharing: ‘vaginalbleedingdischarge’ Then there is the ‘subcat=pregnancyloss,wknum=17’ which crosses a morality line.

How was the data collected?

The data was collected similar to how I collect advertising data on AppGoblin by collecting all network traffic in and out of apps. Jo & Reaves went the additional step of “systematizing app features [and] conduct a series of standardized user interactions across all apps” which enabled them to capture the specific categories and times above like weeks, trimesters and category of pregnancy.

Wasn’t FB & Google investigated and paid millions for doing this?

This joins the massive stories from the past 7 years that started with Facebook in 2019 when it was reported that Flo had set their conversion metrics up based on health sensitive data. Thus Facebook was collecting and targeting their ads based on private data, which they were later fined and found guilty of. In the end Google and Flo Health had multiple settlements and paid $58 million in a class action settlement.

You’d think in 2026 there wouldn’t have been so many apps still sending this data.

Apps in the Paper

Here are the apps called out in the paper. I added URL links to the data I’ve collected about the apps with AppGoblin. AppGoblin only collects data in the first app open and without any interaction, so I was unable to verify the specifics like ‘3rd trimester’ or other data being sent deeper in the user journey as collected by Reaves and Jo.

What you can see on AppGoblin is each of the Ad Networks and data trackers currently integrated with each of the apps.

My original blog post, has full AppGoblin links for each app mentioned in the paper
https://jamesoclaire.com/2026/06/30/the-pregnancy-and-health-apps-still-leaking-data-in-2026/

Anyone interested in looking into this more feel free to DM or reach out via contact page

new research paper:
https://arxiv.org/html/2606.26276v1

I had the $10 copilot subscription for a couple months but cancelled it recently when the overpriced tokens ran out this month. I've been using Deepseek + opencode go just fine.

Today, since the subscription was still 'active' until end of month, I ran out of Inline Code completion requests. You know, those terrible hallucinated crap, I think I used most of them on 'import xxx from xxx' where it just randomly guesses at very plausible sounding function names until I finally just look up the correct path.

Anyways, this ran out, and now I CANNOT rename functions or variables! I've tried completely disabling the completions, but still whenever I press F2 on a function or variable I get that my Copilot subscription "GitHub Copilot Quota Reached".

What's next preventing Search without a subscription??

Agonizing over figuring this out. I have two servers. A home server with plenty of space and a remote cloud VPS that has ~350GB of usable disk space.

I've slowly been solving for this by moving raw data inserts to duckdb + S3 (also locally hosted). Lately though I have fewer and fewer gains that can be made doing this, and am stuck with 'raw' data that I don't easily see how to move into S3, for example:

Raw data mappings

id, app_id, version_str

public.version_strings (9GB)  
id, raw_text

public.version_string_map (28GB)  
version_id, string_id (both FKs)

Which later updated (slowly, sometimes 1hr) with REFRESH CONCURRENTLY into an MV:

CREATE MATERIALIZED VIEW latest_mappings_mv (10GB)
AS SELECT * FROM version_string_map
 JOIN apk_versions
 JOIN version_strings

This is all streaming to the hot-standby read only replica in the cloud with a limited disk.

Technically though, I only need latest_mappings_mv on the remote.

This pattern repeats across 20-40 MVs. There are still some 20 or so 'raw' tables that are also used.

My attempts to solve this

Idea 1: Foreign data wrapper

Create a new postgresql cluster on the home server. Import MVs and tables. This is the new primary for the cloud replica.

The MVs/Tables get made physical with a cache queries like:

-- Wrap in a transaction so pgbackrest streams the changes cleanly
BEGIN;

-- 1. Create the permanent structure if it doesn't exist yet
CREATE TABLE IF NOT EXISTS mytable_clean (
    id INT PRIMARY KEY,
    name TEXT
);

-- 2. Wipe the local data and immediately reload it from the FDW
TRUNCATE mytable_clean;

INSERT INTO mytable_clean (id, name)
SELECT id, name 
FROM mytable; -- (Pulls into port 5444 from cluster on port 5432)

COMMIT;

-- 3. Update the frontend query planner stats
ANALYZE mytable_clean;

Problem

This seems to require extensive manual operations any time a MV changes. It also might require a blue/green style swapping when the big MV to prevent downtime instead of the transaction above?

Idea 2: Logical Replication

This one I've been hesitant about because it also seems like it has the same downsides as the FDW in end: MV schema changes require manual fixes. Additionally, since logical replication does not handle the MVs it would require turning the final MVs into tables and again would need a blue/green strategy to avoid downtimes when updating large MVs?

Idea 3: Could I do more with S3? pg_lake?

I've read other posts here about things like pg_lake, but I'm unclear about the downsides, for example my data ingestion flow does create many small inserts / upserts throughout the day which likely doesn't fit well with parquet files.

I could pass my latest_mappings_mv directly to S3. Then I would pull the latest_mappings_mv back into my main db as a table and could then use logical replication. (not sure if this is correct).

Anyways, just wanted to ask to see if anyone had ideas or tips for where to look next for research or if I'm missing anything.

Working through the pros and cons of the W3 Attribution framework and how it might impact ad measurement. I also focused a bit on AppsFlyer as it was something I was curious to think about how the browser based Attribution could affect or overlap with AppsFlyer's recent released web2app attribution models.

I pay for my parents Starlink and they use it pretty lightly, youtube videos and stuff.

Recently I setup a homelab there with 150tb storage and started syncing to my other home. It's been running for a couple weeks non stop and I guess will finish backing up stuff later in June or July.

Will this affect my starlink? We are on Max plan I think.

I just finished up the AppGoblin 2026 Q1 App Ecosystem Report that shows the quarterly growth for 1k app companies including Ad Networks, Business services, developer tools etc

Report is totally free (no email required) and the raw data is available as well. Also see the AppGoblin free datasets if you are looking for more free raw datasets.

Some takeaways:

Ad Networks were led by Verve once again after its strong Q4 2025, with other notable breakouts from Snap Inc., TaurusX, adjoe, and Moloco.

Business Tools were led by small but super fast growing Luciq. PayPal also posted strong mobile growth, while emerging companies like AppHarbr stood out.

In attribution analytics, growth was broadly healthy across the category and was led by Tenjin. Open source product analytics platform Matomo also looked great heading into 2026.

One notable absence from the growth list was AppsFlyer, which has historically been one of the category's largest and most consistent performers but saw a small down tick in tracked market share.

For Development Tools, Divkit posted solid growth. The framework launched in 2025 and is backed by Yandex.