Last summer Citrix acquired ByteMobile for an undisclosed sum. ByteMobile works with mobile operators -- 130 of them in 60 countries -- to help them better understand how subscribers use their 3G and 4G networks and how best to optimize data services and mobile video services accordingly. Since ByteMobile has a view into what people are actually doing on their mobile phones, it has released an important set of metrics this week -- including a handful related to mobile health adoption -- in its Citrix ByteMobile Mobile Analytics Report for Q1 2013.

What's so interesting about these findings is that they are not based on written questionnaires or verbal surveys with mobile phone users, they are based on the actual activity of (an undisclosed sample size of) users worldwide.

Unfortunately, the report does not include an overall adoption metric for mobile health apps like it does for other apps, services, or activities. (It notes, for example, that on any given day two out of 10 smartphone users will visit an app store.) In the mobile health section of the report, most of the metrics are about subscribers who are already using one or more mobile health applications.

According to ByteMobile, on average, 39 percent of mobile users who are using one or more mobile health applications are using a fitness app. Of all the mobile health related data traffic that operators facilitate, about 50 percent of it comes from personal fitness apps. While fitness apps are generating more data, it seems that pregnancy related apps are actually more popular: On average, 47 percent of total subscribers using one or more mobile health application use a pregnancy related application, according to the report. Despite the popularity of these kinds of apps they don't generate nearly as much data as fitness ones do: Pregnancy monitoring applications generate only 9 percent of the total mobile health related data traffic on wireless networks.

To be clear, ByteMobile is tracking actual usage. It could be that fitness apps have generated more downloads than pregnancy-related apps, but according to this report when it comes to apps that get used -- pregnancy apps have a bigger user base. At the same time, while smaller, the fitness app user base is generating a lot more data.

Beyond fitness trackers and pregnancy-related apps, ByteMobile noted that there are a number of mobile health apps that are popular, including apps that offer calorie counters, medical information, sleep cycle trackers, and relaxation tools.

ByteMobile also found that fitness applications generate the most mobile data traffic around 6:00 PM in the evening, while women's health and pregnancy monitoring apps generated the most data around 9 AM in the morning.