According to research reviewed by Gram, smartphone coaching from early pregnancy through 12 months after birth did not lower body mass index (BMI) more than usual care in women at higher risk of gestational diabetes. In this 2026 randomized trial of 865 women, BMI changes were nearly identical in both groups.
According to research reviewed by Gram, a year of smartphone coaching that started in early pregnancy did not lower body weight more than standard care. The study followed 865 pregnant women across Australia, Ireland, Spain, and the UK who were at higher risk of gestational diabetes, a type of blood sugar problem that can develop during pregnancy. Half received personalized coaching through an app, with support from health coaches, and half received only their usual maternity care. Twelve months after birth, body mass index (BMI), a measure of weight relative to height, was nearly the same in both groups. The coaching group did report fewer side effects and serious problems, although the study was not designed to prove that coaching caused this. The researchers suggest that apps aimed at at-risk mothers may need to address broader health goals beyond weight alone.
Key Statistics
A 2026 randomized controlled trial of 865 pregnant women at higher risk of gestational diabetes found that personalized smartphone coaching from early pregnancy through 12 months after birth did not change BMI compared with usual care.
In the same 2026 trial, 18% of women in the smartphone coaching group reported adverse events compared with 25% of women in the usual care group.
A 2026 trial found that serious adverse events occurred in 6% of coaching participants (28 of 437) compared with 9% of usual care participants (40 of 428).
The Quick Take
- What they studied: Can a personalized smartphone coaching program, starting in early pregnancy and continuing for a year after birth, help women at higher risk of gestational diabetes keep their weight in a healthy range?
- Who participated: 865 pregnant women aged 18 or older, enrolled between 12 and 24 weeks of pregnancy, across four countries. Their average age was about 35 years, and most were White. All had at least one risk factor for gestational diabetes, such as higher body weight, family history of diabetes, or a past gestational diabetes diagnosis.
- Key finding: Women who used the coaching app and women who received usual care had almost the same change in BMI at 12 months after birth. The difference between the groups was less than 0.1 point on the BMI scale, which is too small to matter in everyday life. Fewer women in the coaching group reported side effects or serious problems, but these were not linked to the program.
- What it means for you: A smartphone coaching program did not help women in this study manage their weight after pregnancy more than standard care did. If you are pregnant or planning a pregnancy, talk with your doctor or midwife about proven ways to lower your gestational diabetes risk, such as staying active and eating balanced meals.
The Research Details
This was a randomized controlled trial, which is one of the most reliable ways to test whether a treatment works. Researchers used a computer to randomly assign participants, with equal chances, to either a coaching group or a usual care group. The coaching group used a smartphone app and received support from health coaches who could answer questions and give personal advice, both by scheduled messages and at any time. Both groups received a Bluetooth scale that sent weight readings automatically.
All women continued to receive their normal prenatal and postpartum care, including routine gestational diabetes testing and treatment. Because the coaches and the participants knew which group they were in, the study could not be fully hidden from them. However, the doctors and lab staff who assessed health outcomes did not know which group each woman was in, which helps reduce bias.
The main measure was BMI at 12 months after birth. The study also tracked side effects and serious problems to check whether the program was safe.
Randomly assigning women to groups means that differences between the groups are more likely to come from the coaching program itself rather than from other factors, such as income or health habits. Testing the program across four countries and for a full year after birth also makes the results more useful for real-world decisions. Because the study focused on a single main outcome, its answer about weight is clear, even though it did not capture everything the program might have done.
The study is large, was carried out at multiple sites, was registered in advance with a public trial registry, and used a rigorous randomization method. These features make the findings more trustworthy. The main limitation to keep in mind is that participants and coaches knew who was receiving the program, which can influence how people behave and report their experiences. The trial was funded by the European Union and Australia’s National Health and Medical Research Council, and the published article is from a peer-reviewed journal.
What the Results Show
The main question was whether women in the coaching program lost more weight, measured as BMI, than women who received usual care. They did not. On average, BMI in the coaching group changed by about negative 0.04 points, while the usual care group changed by about 0.04 points. These numbers are so close to zero that they point to no real difference between the groups.
This matters because the program was designed to help women avoid excess weight gain after pregnancy, which can raise the risk of diabetes and other health problems later. The results suggest that a smartphone program alone, even one with personal coaching, did not change the weight outcome that researchers measured in this group of women.
The study enrolled 4,386 women for screening, and 865 were ultimately randomized. This means that a large number of women were not eligible or chose not to join, so the results apply most directly to women who were willing to take part in a long-term digital program.
Adverse events, which are any unwanted health problems recorded during the study, occurred in 18% of women in the coaching group (79 of 437) compared with 25% in the usual care group (106 of 428). Serious adverse events, which are more severe problems that may need hospital care, occurred in 6% of the coaching group (28 of 437) and 9% of the usual care group (40 of 428). The researchers reported that none of these events were related to the intervention. This suggests the coaching program was safe to use, and it may have been linked to slightly fewer problems overall, though this was not the main goal of the study.
Many earlier studies of digital weight programs have found small benefits, especially when used during pregnancy or in the first few months after birth. This trial is unusual because it followed women for a full year after delivery and covered both pregnancy and the postpartum period. Its lack of weight benefit adds to a mixed picture: digital tools can be helpful, but they may not reliably produce weight loss or prevent weight gain on their own. The authors suggest that future programs may need to focus on a wider range of health goals, such as sleep, activity, mental health, and healthy eating habits, rather than weight alone.
Because the coaches and participants knew which group they belonged to, some women may have changed their behavior simply because they knew they were being watched or supported. The study measured BMI, which is a rough measure of body fat and does not show where fat is stored or how muscular a person is. The results also apply mainly to women who agreed to join a long-term digital program, and most participants were White, so the findings may not apply equally to all groups. Finally, the trial measured outcomes only up to 12 months after birth, so it cannot say what happens in later years.
The Bottom Line
Research shows that this smartphone coaching program, used from early pregnancy through a year after birth, did not reduce BMI more than standard care. Confidence in this result is high because the study was a large, well-designed trial. Women at higher risk of gestational diabetes should continue to follow their doctor’s advice on screening, healthy eating, physical activity, and blood sugar monitoring. Digital coaching may still be useful for other goals, such as tracking habits or staying connected with support, but this study does not show it will change weight on its own.
Pregnant women and new mothers who are at higher risk of gestational diabetes, along with the health professionals who support them, should pay attention to these findings. Health system planners and app developers can also use the results to design programs with broader goals. People who are not pregnant, or who are not at increased risk, may find the results less directly relevant, though the study still offers useful information about digital health tools in general.
This study looked at changes over a full year after birth, so results from a program like this are best judged over months rather than weeks. In this trial, no meaningful difference in BMI appeared at 12 months. Anyone using a digital health tool should expect that it may help with habits or support, but weight changes typically take many months and depend on many factors, including diet, sleep, activity, and overall health.
Frequently Asked Questions
Does a smartphone coaching app help pregnant women lose weight after birth?
In a 2026 randomized trial of 865 women, app-based coaching from early pregnancy to 12 months postpartum did not lower BMI compared with usual care. Average BMI changes were nearly identical in both groups, so the program did not show a weight benefit on its own.
What is gestational diabetes and who is at higher risk?
Gestational diabetes is a form of high blood sugar that develops during pregnancy. Risk is higher for women with higher BMI, older age, certain ethnic backgrounds, a family history of diabetes, or a past gestational diabetes diagnosis, and doctors often use a risk tool to assess this.
Is mobile health coaching safe during pregnancy?
In a 2026 trial of 865 women, adverse events were reported by 18% of the coaching group and 25% of the usual care group. Researchers found no adverse events linked to the coaching program itself, though pregnant women should always check with their healthcare provider first.
How can I lower my risk of gestational diabetes?
Staying physically active, eating balanced meals with plenty of vegetables and fiber, and maintaining a healthy weight before and during pregnancy can help lower risk. Your doctor can screen you early and recommend a plan that fits your health needs and medical history.
Want to Apply This Research?
- Track your weight with a Bluetooth scale or on a set schedule, such as once a week at the same time of day, and record it alongside your meals and activity minutes. Also log how many days per week you meet your activity goal and how many servings of vegetables you eat, so you can see patterns over time.
- Set one small, specific goal each week, such as a 20-minute walk on three days or adding a vegetable to lunch, and use the app to schedule reminders. Review your progress with your health coach or doctor each month and adjust the goal if it feels too hard or too easy.
- Use the app to record weight, activity, and eating habits at least weekly during pregnancy, then monthly after birth through the first year. Look at trends across three to six months rather than reacting to single readings, and share the summary with your healthcare provider at each visit. Pay attention to how you feel overall, including energy, mood, and sleep, since these matter as much as the scale.
This article summarizes a single research study for general information only and is not medical advice. Pregnancy and postpartum health needs vary widely, so always speak with your doctor, midwife, or other qualified healthcare provider before changing your diet, exercise, weight management plan, or use of any health app. Do not stop or change prescribed medical care based on this information.
This research translation is published by Gram Research, the science division of Gram, an AI-powered nutrition tracking app.